MATERIALS AND METHODS FOR TREATMENT OF AUTOSOMAL DOMINANT

CONE-ROD DYSTROPHY

FIELD

[0001] The present application provides materials and methods for treating autosomal dominant Cone-Rod Dystrophy (CORD).

RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62/598,682 filed December 14, 2017; U.S. Provisional Application No. 62/670,378 filed May 11, 2018; U.S. Provisional Application No. 62/675,306 filed May 23, 2018; and U.S. Provisional Application No. 62/693, 100 filed July 2, 2018, all of which are incorporated herein in their entirety by reference.

INCORPORATION BY REFERENCE OF SEQUENCE LISTING

[0003] This application contains a Sequence Listing in computer readable form (filename: 170587PCT GUCY2D Sequence Listing_ST25 : 10,212,755 bytes— ASCII text file; created December 7, 2018), which is incorporated by reference in its entirety and forms part of the disclosure.

BACKGROUND

[0004] Cone-rod dystrophies (CORD) are genetic ocular disorders characterized by the loss of cone cells, the photoreceptors responsible for both central and color vision. CORD can cause a variety of symptoms including decreased central visual acuity and photophobia, which is a reduced ability to see colors and an increased sensitivity to light, both of which can be early symptoms. Later symptoms can include night blindness and further decrease of visual acuity. Mutations associated with CORD have been identified, including mutations in the GUCY2D gene.

[0005] Currently, there are no adequate treatments or therapies to prevent the development of CORD or to restore vision, and there remains a critical need for developing safe and effective treatments for CORD. SUMMARY

[0006] The present disclosure presents a novel method to ameliorate, if not eliminate, an autosomal dominant CORD. The novel approach targets a mutation in the GUCY2D gene, such as an R838H, R838C, or R838S mutation, with a method resulting in the reduction or elimination of expression of the defective protein encoded by a gene containing the mutation. Furthermore, in some cases, the treatment can be effected with a small number of treatments and, in some cases, with a single treatment. The resulting therapy can ameliorate autosomal dominant CORD associated with a mutant GUCY2D gene or, in some cases, can eliminate autosomal dominant CORD associated with a mutant GUCY2D gene.

[0007] Provided herein is a method for editing a GUCY2D gene in a human cell. The method comprises introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the GUCY2D gene or other DNA sequences that encode regulatory elements of the GUCY2D gene that results in a deletion, insertion, or correction thereby creating an edited human cell.

[0008] Also provided herein is a method for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell. The method comprises: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H,

R838C, or R838S mutation in a GUCY2D gene that results in a deletion, insertion, or correction thereby creating an edited human cell.

[0009] Also provided herein is a method for editing a GUCY2D gene in a human cell. The method comprises introducing into the human cell one or more deoxyribonucleic acid (DNA) endonucleases to effect one or more single-strand breaks (SSBs) or double-strand breaks (DSBs) within or near the GUCY2D gene or other DNA sequences that encode regulatory elements of the GUCY2D gene that results in a modulation of expression or function of the GUCY2D gene thereby creating an edited human cell.

[00010] Also provided herein is a method for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell. The method comprises: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H,

R838C, or R838S mutation in a GUCY2D gene that results in a modulation of expression or function of the GUCY2D gene thereby creating an edited human cell.

[00011] Also provided herein is an in vivo method for treating a patient with autosomal dominant CORD. The method comprises: editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a cell of the patient. [00012] Also provided herein is one or more gRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD. The one or more gRNAs comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 of the Sequence Listing.

[00013] Also provided herein is a gRNA for editing a R838H or R838C mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD. The gRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in 5398-5409 of the Sequence Listing.

[00014] Also provided herein is a gRNA for editing a R838H or R838S mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD. The gRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in 5434-5443 of the Sequence Listing.

[00015] Also provided herein is a therapeutic for treating a patient with autosomal dominant Cone-Rod Dystrophy, the therapeutic comprising at least one or more gRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene. The one or more gRNAs comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 of the Sequence Listing.

[00016] Also provided herein is a therapeutic for treating a patient with autosomal dominant Cone-Rod Dystrophy, the therapeutic comprising a gRNA for editing a R838H or R838C mutation in a GUCY2D gene. The gRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in 5398-5409 of the Sequence Listing.

[00017] Also provided herein is a therapeutic for treating a patient with autosomal dominant Cone-Rod Dystrophy, the therapeutic comprising a gRNA for editing a R838H or R838S mutation in a GUCY2D gene. The gRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in 5434-5443 of the Sequence Listing.

[00018] Also provided herein is a therapeutic for treating a patient with autosomal dominant CORD, the therapeutic formed by a method comprising: introducing one or more DNA endonucleases; introducing one or more gRNA or one or more sgRNA for editing a R838H, R838C, or R838S mutation in a GUCY2D gene; and optionally introducing one or more donor template. The one or more gRNAs or sgRNAs comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434- 5443 of the Sequence Listing. [00019] Also provided herein is a therapeutic for treating a patient with autosomal dominant CORD, the therapeutic formed by a method comprising: introducing one or more DNA endonucleases; introducing a gRNA or sgRNA for editing a R838H or R838C mutation in a GUCY2D gene; and optionally introducing one or more donor template. The gRNA or sgRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398-5409 of the Sequence Listing.

[00020] Also provided herein is a therapeutic for treating a patient with autosomal dominant CORD, the therapeutic formed by a method comprising: introducing one or more DNA endonucleases; introducing a gRNA or sgRNA for editing a R838H or R838S mutation in a GUCY2D gene; and optionally introducing one or more donor template. The gRNA or sgRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5434-5443 of the Sequence Listing.

[00021] Also provided herein is a kit for treating a patient with autosomal dominant CORD in vivo. The kit comprises one or more gRNAs or sgRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene, one or more DNA endonucleases; and optionally, one or more donor template. The one or more gRNAs or sgRNAs comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 of the Sequence Listing.

[00022] Also provided herein is a kit for treating a patient with autosomal dominant CORD in vivo. The kit comprises a gRNA or sgRNA for editing a R838H or R838C mutation in a GUCY2D gene, one or more DNA endonucleases; and optionally, one or more donor template. The gRNA or sgRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398-5409 of the Sequence Listing.

[00023] Also provided herein is a kit for treating a patient with autosomal dominant CORD in vivo. The kit comprises a gRNA or sgRNA for editing a R838H or R838S mutation in a GUCY2D gene, one or more DNA endonucleases; and optionally, one or more donor template. The gRNA or sgRNA comprises a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5434-5443 of the Sequence Listing.

[00024] Also provided herein is a single -molecule guide RNA (sgRNA) comprising the nucleic acid sequence of SEQ ID NO: 5285.

[00025] Also provided herein is a single -molecule guide RNA (sgRNA) comprising the nucleic acid sequence of SEQ ID NO: 5398. [00026] Also provided herein is a single-molecule guide RNA (sgRNA) comprising the nucleic acid sequence of SEQ ID NO: 5286.

[00027] Also provided herein is a single -molecule guide RNA (sgRNA) comprising the nucleic acid sequence of SEQ ID NO: 5464.

[00028] Also provided herein is a single -molecule guide RNA (sgRNA) comprising the nucleic acid sequence of SEQ ID NO: 5465.

[00029] Also provided herein is a single -molecule guide RNA (sgRNA) comprising the nucleic acid sequence of SEQ ID NO: 5466.

[00030] Also provided herein is a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5285.

[00031] Also provided herein is a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5286.

[00032] Also provided herein is a method for editing an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5398.

[00033] Also provided herein is a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5464.

[00034] Also provided herein is a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5465.

[00035] Also provided herein is a method for editing an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5466.

[00036] Also provided herein is a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5285 to the patient.

[00037] Also provided herein is a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5286 to the patient.

[00038] Also provided herein is a method for treating a patient with an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5398 to the patient. [00039] Also provided herein is a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5464 to the patient.

[00040] Also provided herein is a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5465 to the patient.

[00041] Also provided herein is a method for treating a patient with an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5466 to the patient.

[00042] Also provided herein is a self-inactivating CRISPR-Cas system. The self-inactivating CRISPR-Cas system comprises a first segment, a second segment, and one or more third segments. The first segment comprises a nucleotide sequence that encodes a polypeptide inducing site-directed mutagenesis. The second segment comprises a nucleotide sequence that encodes a guide RNA (gRNA) or a single -molecule guide RNA (sgRNA) wherein the gRNA or sgRNA comprise SEQ ID NO: 5285 or 5464. The one or more third segments comprise a self- inactivating (SIN) site. The gRNA or sgRNA is substantially complementary to the SIN site.

The gRNA or sgRNA is substantially complementary to a genomic target sequence.

[00043] Also provided herein is a self-inactivating CRISPR-Cas system. The self-inactivating CRISPR-Cas system comprises a first segment, a second segment, and one or more third segments. The first segment comprises a nucleotide sequence that encodes a polypeptide inducing site-directed mutagenesis. The second segment comprises a nucleotide sequence that encodes a guide RNA (gRNA) or a single -molecule guide RNA (sgRNA) wherein the gRNA or sgRNA comprise SEQ ID NO: 5398 or 5466. The one or more third segments comprise a self- inactivating (SIN) site. The gRNA or sgRNA is substantially complementary to the SIN site.

The gRNA or sgRNA is substantially complementary to a genomic target sequence.

[00044] Also provided herein is a self-inactivating CRISPR-Cas system. The self-inactivating CRISPR-Cas system comprises a first segment, a second segment, and one or more third segments. The first segment comprises a nucleotide sequence that encodes a SpCas9 or any variants thereof. The second segment comprises a nucleotide sequence that encodes a gRNA or sgRNA. The one or more third segments comprise a self-inactivating (SIN) site. The gRNA or sgRNA is substantially complementary to the SIN site. The gRNA or sgRNA is substantially complementary to a genomic target sequence. The SIN site comprises a sequence selected from the group consisting of SEQ ID NOs: 5478-5492 [00045] It is understood that the inventions described in this specification are not limited to the examples summarized in this Summary. Various other aspects are described and exemplified herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[00046] Various aspects of materials and methods for treatment of automosomal dominant CORD disclosed and described in this specification can be better understood by reference to the accompanying figures, in which:

[00047] Figures 1 A-B depict the type II CRISPR/Cas system.

[00048] Figure 1A depicts the type II CRISPR/Cas system including gRNA.

[00049] Figure 1B depicts the type II CRISPR/Cas system including sgRNA.

[00050] Figures 2A-C show the sgRNA sequence, the target DNA sequence, and the reverse strand of the target DNA sequence to which the sgRNA binds, for each of 42 sgRNA sequences.

[00051] Figure 2A shows the sgRNA sequence, for each of 42 sgRNA sequences.

[00052] Figure 2B shows the target DNA sequence, for each of 42 sgRNA sequences.

[00053] Figure 2C shows the reverse strand of the target DNA sequence to which the sgRNA binds, for each of 42 sgRNA sequences.

[00054] Figures 2D-F show the sgRNA sequence, the target DNA sequence, and the reverse strand of the target DNA sequence to which the sgRNA binds, for each of 22 sgRNA sequences.

[00055] Figure 2D shows the sgRNA sequence, for each of 22 sgRNA sequences.

[00056] Figure 2E shows the target DNA sequence, for each of 22 sgRNA sequences.

[00057] Figure 2F shows the reverse strand of the target DNA sequence to which the sgRNA binds, for each of 22 sgRNA sequences.

[00058] Figures 3A-F are maps depicting the target DNA sequences for gRNAs targeting the wild-type GUCY2D gene or gRNAs targeting the R838H, R838C, or R838S mutation within the GUCY2D gene.

[00059] Figure 3A is a map depicting the target DNA sequences for gRNAs that target the wild-type GUCY2D gene.

[00060] Figure 3B is a map depicting the target DNA sequences for gRNAs that target the R838H mutation within the GUCY2D gene.

[00061] Figure 3C is a map depicting the target DNA sequences for gRNAs that target the R838C mutation within the GUCY2D gene. [00062] Figure 3D is a map depicting the target DNA sequences for gRNAs that target the R838S mutation within the GUCY2D gene.

[00063] Figure 3E is a map depicting the target DNA sequences for gRNAs that target both the R838H mutation and R838C mutation within the GUCY2D gene.

[00064] Figure 3F is a map depicting the target DNA sequences for gRNAs that target both the R838H mutation and R838S mutation within the GUCY2D gene.

[00065] Figures 4A-E describe the on-target editing efficiency of sgRNAs targeting the wild- type GUCY2D gene and the off-target editing efficiency of sgRNAs targeting the R838H, R838C, or R838S mutation within the GUCY2D gene.

[00066] Figure 4A describes the on-target editing efficiency of sgRNAs targeting the wild- type GUCY2D gene (sgRNAs comprising SEQ ID NO: 5274 or 5278) and the off-target editing efficiency of sgRNAs targeting the R838H, R838C, or R838S mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5284, 5289, 5296, 5300, 5304, 5308, 5398, or 5403).

[00067] Figure 4B describes the on-target editing efficiency of sgRNAs targeting the wild- type GUCY2D gene (sgRNAs comprising SEQ ID NO: 5275 or 5279) and the off-target editing efficiency of sgRNAs targeting the R838H, R838C, or R838S mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5285, 5290, 5297, 5301, 5305, 5309, 5399, or 5404).

[00068] Figure 4C describes the on-target editing efficiency of gRNAs targeting the wild-type GUCY2D gene (sgRNAs comprising SEQ ID NO: 5276 or 5280) and the off-target editing efficiency of sgRNAs targeting the R838H, R838C, or R838S mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5286, 5291, 5298, 5302, 5306, 5310, 5400, or 5405).

[00069] Figure 4D describes the on-target editing efficiency of sgRNAs targeting the wild- type GUCY2D gene (sgRNAs comprising SEQ ID NO: 5277 or 5281) and the off-target editing efficiency of sgRNAs targeting the R838H, R838C, or R838S mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5287, 5292, 5299, 5303, 5307, 5311, 5402, or 5407).

[00070] Figure 4E describes the off-target editing efficiency of sgRNAs targeting the R838H or R838C mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5288, 5293, 5401, or 5406).

[00071] Figure 5 describes the on-target editing efficiency of sgRNAs targeting the wild-type GUCY2D gene of a plasmid (a sgRNA comprising SEQ ID NO: 5274) and the on-target editing efficiency of sgRNAs targeting the R838H within the GUCY2D gene of a plasmid (sgRNAs comprising SEQ ID NO: 5284, 5285, 5286, 5287, 5288, 5398, 5399, 5400, 5401, or 5402). [00072] Figures 6A-B describe the on-target and off-target editing efficiency of a plasmid transcribed sgRNA targeting the wild-type GUCY2D gene (a sgRNA comprising SEQ ID NO: 5274) at 48 or 72 hours post transfection and the on-target and off-target editing efficiency of plasmid transcribed sgRNAs targeting the R838H or R838C mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5285, 5286, 5398, 5399, or 5402) at 48 or 72 hours post transfection.

[00073] Figure 6A describes the on-target and off-target editing efficiency of a plasmid transcribed sgRNA targeting the wild-type GUCY2D gene (a sgRNA comprising SEQ ID NO: 5274) at 48 hours post transfection and the on-target and off-target editing efficiency of plasmid transcribed sgRNAs targeting the R838H or R838C mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5285, 5286, 5398, 5399, or 5402) at 48 hours post transfection.

[00074] Figure 6B describes the on-target and off-target editing efficiency of a plasmid transcribed sgRNA targeting the wild-type GUCY2D gene (a sgRNA comprising SEQ ID NO: 5274) at 72 hours post transfection and the on-target and off-target editing efficiency of plasmid transcribed sgRNAs targeting the R838H or R838C mutation within the GUCY2D gene of a plasmid (sgRNAs comprising SEQ ID NO: 5285, 5286, 5398, 5399, or 5402) at 72 hours post transfection.

[00075] Figures 7A-J show a donor plasmid used to prepare 3 different HEK 293FT reporter cell lines and flow cytometry data for the 3 different HEK 293FT reporter cell lines that are co transfected with a plasmid encoding SpCas9 driven by human EFla core promoter and a plasmid containing R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285), or R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) under U6 promoter, or no sgRNA.

[00076] Figure 7A depicts a donor plasmid comprising a Cas9 target site (either a wild-type GUCY2D gene, a GUCY2D gene comprising a R838H mutation, or a GUCY2D gene comprising a R838C mutation) fused to a blue flurescence protein.

[00077] Figure 7B shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with a plasmid encoding SpCas9 driven by human elongation factor 1 alpha (EFla) core promoter and a plasmid containing R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) under U6 promoter.

[00078] Figure 7C shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with a plasmid encoding SpCas9 driven by human EFla core promoter and a plasmid containing

R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) under U6 promoter.

[00079] Figure 7D shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are not transfected with any sgRNA.

[00080] Figure 7E shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with a plasmid encoding SpCas9 driven by human EFla core promoter and a plasmid containing R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) under U6 promoter.

[00081] Figure 7F shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with a plasmid encoding SpCas9 driven by human EFla core promoter and a plasmid containing R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) under U6 promoter.

[00082] Figure 7G shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are not transfected with any sgRNA.

[00083] Figure 7H shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with a plasmid encoding SpCas9 driven by human EFla core promoter and a plasmid containing R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) under U6 promoter.

[00084] Figure 71 shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with a plasmid encoding SpCas9 driven by human EFla core promoter and a plasmid containing R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) under U6 promoter.

[00085] Figure 7J shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are not transfected with any sgRNA.

[00086] Figures 8A-B are graphs showing the percent reduction of cGMP and absolute cGMP for HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and IVT sgRNAs that target the R838H mutation within the GUCY2D gene.

[00087] Figure 8A is a graph showing the percent reduction of cGMP for HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and IVT sgRNAs that target the R838H mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5284, 5285,

5286, 5287, 5288, 5289, 5290, 5291, 5292, or 5293).

[00088] Figure 8B is a graph showing the absolute cGMP for HEK293T-SpCas9 cells co transfected with a vector containing R838H cDNA and IVT sgRNAs that target the R838H mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5284, 5285, 5286, 5287, 5288, 5289, 5290, 5291, 5292, or 5293).

[00089] Figures 9A-B are graphs showing the percent reduction of cGMP and absolute cGMP for HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and IVT sgRNAs that target the R838H mutation within the GUCY2D gene.

[00090] Figure 9A is a graph showing the percent reduction of cGMP for HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and IVT sgRNAs that target the R838H mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5285, 5286, or 5291).

[00091] Figure 9B is a graph showing the absolute cGMP for HEK293T-SpCas9 cells co transfected with a vector containing R838H cDNA and IVT sgRNAs that target the R838H mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NO: 5285, 5286, or 5291).

[00092] Figures 10A-B are graphs showing the percent reduction of cGMP and absolute cGMP for HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and pAAV-U6-R838 sgRNA that targets the R838H mutation within the GUCY2D gene.

[00093] Figure 10A is a graph showing the percent reduction of cGMP for HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and pAAV-U6-R838 sgRNA that targets the R838H mutation within the GUCY2D gene (pAAV-5285 or pAAV-5286).

[00094] Figure 10B is a graph showing the absolute cGMP for HEK293T-SpCas9 cells co transfected with a vector containing R838H cDNA and pAAV-U6-R838 sgRNA that targets the R838H mutation within the GUCY2D gene (pAAV-5285 or pAAV-5286).

[00095] Figures 11 A-D depict the structural arrangement of SIN-AAV SpCas9 version 1 (sEFla promoter), SIN-AAV SpCas9 version 2 (sEFla promoter), Non-SIN-AAV SpCas9 (sEFla promoter), and the AAV sequence of pSIA0l2 and pSIA0l5.

[00096] Figure 11A depicts the structural arrangement of SIN-AAV SpCas9 version 1 (sEFla promoter).

[00097] Figure 11B depicts the structural arrangement of SIN-AAV SpCas9 version 2 (sEFla promoter).

[00098] Figure 11C depicts the structural arrangement of Non-SIN-AAV SpCas9 (sEFla promoter).

[00099] Figure 11D depicts the structural arrangement of an AAV sequence of pSIA0l2 and pSIA0l5. pSIA0l2 is a plasmid comprising an AAV sequence that encodes a sgRNA comprising SEQ ID NO: 5285. pSIA0l5 is a plasmid comprising an AAV sequence that encodes a sgRNA comprising SEQ ID NO: 5398.

[000100] Figures 12A-U show flow cytometry data for 3 different HEK 293FT reporter cell lines that are co-transfected with pSIA0l2, a plasmid comprising an AAV sequence that encodes R838H_Sp_T2 sgRNA (a sgRNA comprising SEQ ID NO: 5285) or pSIA0l5, a plasmid comprising an AAV sequence that encodes R838CH_Sp_Tl sgRNA (a sgRNA comprising SEQ ID NO: 5398), and either (1) a SIN-AAV SpCas9 version 1 (sEFla promoter), (2) a SIN-AAV SpCas9 version 2 (sEFla promoter), or (3) aNon-SIN-AAV SpCas9 (sEFla promoter).

[000101] Figure 12A shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a SIN-AAV SpCas9 version 1 (sEFla).

[000102] Figure 12B shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) a SIN-AAV SpCas9 version 1 (sEFla).

[000103] Figure 12C shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a SIN-AAV SpCas9 version 1 (sEFla).

[000104] Figure 12D shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) a SIN-AAV SpCas9 version 1 (sEFla).

[000105] Figure 12E shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a SIN-AAV SpCas9 version 1 (sEFla).

[000106] Figure 12F shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) a SIN-AAV SpCas9 version 1 (sEFla).

[000107] Figure 12G shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a SIN-AAV SpCas9 version 2 (sEFla).

[000108] Figure 12H shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with a (1) pSIA0l5 and a (2) SIN-AAV SpCas9 version 2 (sEFla). [000109] Figure 121 shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a SIN-AAV SpCas9 version 2 (sEFla).

[000110] Figure 12J shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) a SIN-AAV SpCas9 version 2 (sEFla).

[000111] Figure 12K shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a SIN-AAV SpCas9 version 2 (sEFla).

[000112] Figure 12L shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) a SIN-AAV SpCas9 version 2 (sEFla).

[000113] Figure 12M shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a Non-SIN-AAV SpCas9 (sEFla).

[000114] Figure 12N shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) a Non-SIN-AAV SpCas9 (sEFla).

[000115] Figure 120 shows flow cytometry data for HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that are not transfected with any DNA.

[000116] Figure 12P shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a Non-SIN-AAV SpCas9 (sEFla).

[000117] Figure 12Q shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) a Non-SIN-AAV SpCas9 (sEFla).

[000118] Figure 12R shows flow cytometry data for HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that are not transfected with any DNA.

[000119] Figure 12S shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l2 and (2) a Non-SIN-AAV SpCas9 (sEFla). [000120] Figure 12T shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are co-transfected with (1) pSIA0l5 and (2) Non-SIN-AAV SpCas9 (sEFla).

[000121] Figure 12U shows flow cytometry data for HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that are not transfected with any sgRNA.

[000122] Figures 13A-C show western blot data for 3 different HEK 293FT reporter cell lines that are co-transfected with either pSIA0l2, a plasmid comprising an AAV sequence that encodes R838H_Sp_T2 sgRNA (a sgRNA comprising SEQ ID NO: 5285) or pSIA0l5, a plasmid comprising an AAV sequence that encodes R838CH_Sp_Tl sgRNA (a sgRNA comprising SEQ ID NO: 5398) and either (1) a SIN-AAV SpCas9 version 1 (sEFla promoter), (2) a SIN-AAV SpCas9 version 2 (sEFla promoter), or (3) a Non-SIN-AAV SpCas9 (sEFla promoter).

[000123] Figure 13A is a western blot showing SpCas9, Actin, and GFP expression in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site. These HEK 293FT reporter cells are transfected with either pSIA0l2 or pSIA0l5. The HEK 293FT reporter cells are also transfected with either (1) a SIN-AAV SpCas9 version 1 (sEFla promoter), (2) a SIN-AAV SpCas9 version 2 (sEFla promoter), or (3) a Non-SIN-AAV SpCas9 (sEFla promoter).

[000124] Figure 13B is a western blot showing SpCas9, Actin, and GFP expression in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site. These HEK 293 FT reporter cells are transfected with either pSIA0l2 or pSIA0l5. The HEK 293FT reporter cells are also transfected with either (1) a SIN-AAV SpCas9 version 1 (sEFla promoter), (2) a SIN- AAV SpCas9 version 2 (sEFla promoter), or (3) a Non-SIN-AAV SpCas9 (sEFla promoter).

[000125] Figure 13C is a western blot showing SpCas9, Actin, and GFP expression in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site. These HEK 293 FT reporter cells are transfected with either pSIA0l2 or pSIA0l5. The HEK 293FT reporter cells are also transfected with either (1) a SIN-AAV SpCas9 version 1 (sEFla promoter), (2) a SIN- AAV SpCas9 version 2 (sEFla promoter), or (3) a Non-SIN-AAV SpCas9 (sEFla promoter).

[000126] Figures 14A-C depict the structural arrangement of SIN-AAV SpCas9 version 1 (GRK1 promoter), SIN-AAV SpCas9 version 2 (GRK1 promoter), and Non-SIN-AAV SpCas9 (GRK1 promoter).

[000127] Figure 14A depicts the structural arrangement of SIN-AAV SpCas9 version 1 (GRK1 promoter). [000128] Figure 14B depicts the structural arrangement of SIN-AAV SpCas9 version 2 (GRK1 promoter).

[000129] Figure 14C depicts the structural arrangement of Non-SIN-AAV SpCas9 (GRK1 promoter).

[000130] Figures 15A-B are western blots showing SpCas9, Beta-Tubulin, and GFP expression in cells isolated from mouse retinas that were previously injected with either an AAV that encodes R838H_Sp_T2 sgRNA (a sgRNA comprising SEQ ID NO: 5285) or AAV that encodes R838CH_Sp_Tl sgRNA (a sgRNA comprising SEQ ID NO: 5398). Mouse retinas were co injected with AAV-R838H (SEQ ID NO: 5481) and either (1) a SIN-AAV SpCas9 version 1 (GRK1), (2) a SIN-AAV SpCas9 version 2 (GRK1), or (3) a Non-SIN-AAV SpCas9 (GRK1).

[000131] Figure 15A is a western blot showing SpCas9, Beta-Tubulin, and GFP expression in cells isolated from mouse retinas that were previously injected with an AAV vector that encodes R838H_Sp_T2 sgRNA (a sgRNA comprising SEQ ID NO: 5285); AAV-R838H (SEQ ID NO: 5481); and either (1) a SIN-AAV SpCas9 version 1 (GRK1), (2) a SIN-AAV SpCas9 version 2 (GRK1), or (3) a Non-SIN-AAV SpCas9 (GRK1).

[000132] Figure 15B is a western blot showing SpCas9, Beta-Tubulin, and GFP expression in cells isolated from mouse retinas that were previously injected with an AAV vector that encodes R838CH_Sp_Tl sgRNA (a sgRNA comprising SEQ ID NO: 5398); AAV-R838H (SEQ ID NO: 5481); and either (1) a SIN-AAV SpCas9 version 1 (GRK1), (2) a SIN-AAV SpCas9 version 2 (GRK1), or (3) a Non-SIN-AAV SpCas9 (GRK1).

[000133] Figure 16 is a graph showing the editing efficiency for immortalized human patient- derived fibroblasts that have a R838H mutant allele as a copy of the GUCY2D gene, co transfected with pSpCas9, a plasmid that encodes SpCas9, and either: pSIA0l2, pSIA0l5, or pSIA003.

[000134] Figure 17 is a graph showing the editing efficiency for immortalized human patient- derived fibroblasts that have a R838C mutant allele as a copy of the GUCY2D gene, co transfected with pSpCas9, a plasmid that encodes SpCas9, and either: pSIA0l2, pSIA0l5, or pSIA003.

[000135] Figure 18 is a graph showing the editing efficiency for hTERT-immortalized human fibroblast cells that are homozygous for the wild-type copy of the GUCY2D gene, co-transfected with pSpCas9, a plasmid that encodes SpCas9, and either: pSIA0l2, pSIA0l5, pSIA022, or pSIA003. BRIEF DESCRIPTION OF THE SEQUENCE LISTING

[000136] SEQ ID NOs: 1-612 are Cas endonuclease ortholog sequences.

[000137] SEQ ID NOs: 613-4696 are miRNA sequences.

[000138] SEQ ID NOs: 4697-5265 are AAV serotype sequences.

[000139] SEQ ID NO: 5266 is a GUCY2D nucleotide sequence.

[000140] SEQ ID NOs: 5267- 5269 show sample sgRNA backbone sequences that SpCas9 is complexed with.

[000141] SEQ ID NO: 5270 is a sample gRNA for a Streptococcus pyogenes Cas9

endonuclease.

[000142] SEQ ID NO: 5271 shows a known family of homing endonuclease, as classified by its structure.

[000143] SEQ ID NOs: 5272 - 5281 are 19-20 bp spacer sequences for targeting within or near a GUCY2D gene or other DNA sequence that encodes a regulatory element of the GUCY2D gene with a S. pyogenes Cas9 endonuclease or S. aureus Cas9 endonuclease.

[000144] SEQ ID NOs: 5282 - 5293 are 19-20 bp spacer sequences for targeting within or near a R838H mutation in a GUCY2D gene with a S. pyogenes Cas9 endonuclease or S. aureus Cas9 endonuclease.

[000145] SEQ ID NOs: 5294 - 5303 are 19-20 bp spacer sequences for targeting within or near a R838C mutation in a GUCY2D gene with a S. pyogenes Cas9 endonuclease or S. aureus Cas9 endonuclease.

[000146] SEQ ID NOs: 5304 - 5313 are 19-20 bp spacer sequences for targeting within or near a R838S mutation in a GUCY2D gene with a S. pyogenes Cas9 endonuclease or S. aureus Cas9 endonuclease.

[000147] SEQ ID NOs: 5314-5355 are sequences that represent the target DNA sequences, for each of 42 sgRNA sequences in Figure 2A.

[000148] SEQ ID NOs: 5356-5397 are sequences that represent the reverse strands of the target DNA sequence to which the sgRNA will bind, for each of 42 sgRNA sequences in Figure 2A.

[000149] SEQ ID NOs: 5398-5409 are 19-20 bp spacer sequences for targeting within or near a R838H mutation or R838C mutation in a GUCY2D gene with a S. pyogenes Cas9 endonuclease or Staphylococcus aureus Cas9 endonuclease.

[000150] SEQ ID NOs: 5410-5421 are sequences that represent the target DNA sequences, for each of 12 sgRNA sequences in Figure 2D. [000151] SEQ ID NOs: 5422-5433 are sequences that represent the reverse strands of the target DNA sequence to which the sgRNA will bind, for each of 12 sgRNA sequences in Figure 2D.

[000152] SEQ ID NOs: 5434-5443 are 19-20 bp spacer sequences for targeting within or near a R838H mutation or R838S mutation in a GUCY2D gene with a S. pyogenes Cas9 endonuclease or A aureus Cas9 endonuclease.

[000153] SEQ ID NOs: 5444-5453 are sequences that represent the target DNA sequences, for each of 10 sgRNA sequences in Figure 2D.

[000154] SEQ ID NOs: 5454-5463 are sequences that represent the reverse strands of the target DNA sequence to which the sgRNA will bind, for each of 10 sgRNA sequences in Figure 2D.

[000155] SEQ ID NO: 5464 is a full-length sgRNA comprising SEQ ID NOs: 5285 and 5267.

[000156] SEQ ID NO: 5465 is a full-length sgRNA comprising SEQ ID NOs: 5286 and 5267.

[000157] SEQ ID NO: 5466 is a full-length sgRNA comprising SEQ ID NOs: 5398 and 5267.

[000158] SEQ ID NO: 5467 does not include a sequence.

[000159] SEQ ID NO: 5468 is a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NOs: 5274 and 5267.

[000160] SEQ ID NO: 5469 is pSIA0l2, a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5464.

[000161] SEQ ID NO: 5470 is a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5465.

[000162] SEQ ID NO: 5471 is pSIA0l5, a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5466.

[000163] SEQ ID NO: 5472 is a plasmid sequence comprising SIN-AAV SpCas9 ver. 1 (GRK1 promoter), depicted in Figure 14A.

[000164] SEQ ID NO: 5473 is a plasmid sequence comprising SIN-AAV SpCas9 ver. 2 (GRK1 promoter), depicted in Figure 14B.

[000165] SEQ ID NO: 5474 is a plasmid sequence comprising Non-SIN-AAV SpCas9 (GRK1 promoter), depicted in Figure 14C.

[000166] SEQ ID NO: 5475 is a plasmid sequence comprising SIN-AAV SpCas9 ver. 1 (sEFla promoter), depicted in Figure 11A.

[000167] SEQ ID NO: 5476 is a plasmid sequence comprising SIN-AAV SpCas9 ver. 2 (sEFla promoter), depicted in Figure 11B.

[000168] SEQ ID NO: 5477 is a plasmid sequence comprising Non-SIN-AAV SpCas9 (sEFla promoter), depicted in Figure 11C. [000169] SEQ ID NO: 5478 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver.l, depicted in Figures 11A and 14A.

[000170] SEQ ID NO: 5479 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver. 2, depicted in Figures 11B and 14B.

[000171] SEQ ID NO: 5480 is a possible SIN site located downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 1 depicted in Figures 11A and 14A and downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 2 depicted in Figures 11B and 14B.

[000172] SEQ ID NO: 5481 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver.l, depicted in Figures 11A and 14A.

[000173] SEQ ID NO: 5482 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver. 2, depicted in Figures 11B and 14B.

[000174] SEQ ID NO: 5483 is a possible SIN site located downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 1 depicted in Figures 11A and 14A and downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 2 depicted in Figures 11B and 14B.

[000175] SEQ ID NO: 5484 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver.l, depicted in Figures 11A and 14A.

[000176] SEQ ID NO: 5485 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver. 2, depicted in Figures 11B and 14B.

[000177] SEQ ID NO: 5486 is a possible SIN site located downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 1 depicted in Figures 11A and 14A and downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 2 depicted in Figures 11B and 14B.

[000178] SEQ ID NO: 5487 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver.l, depicted in Figures 11A and 14A.

[000179] SEQ ID NO: 5488 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver. 2, depicted in Figures 11B and 14B.

[000180] SEQ ID NO: 5489 is a possible SIN site located downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 1 depicted in Figures 11A and 14A and downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 2 depicted in Figures 11B and 14B.

[000181] SEQ ID NO: 5490 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver.l, depicted in Figures 11A and 14A.

[000182] SEQ ID NO: 5491 is a possible SIN site located upstream of the SpCas9 ORF in the SIN-AAV SpCas9 ver. 2, depicted in Figures 11B and 14B. [000183] SEQ ID NO: 5492 is a possible SIN site located downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 1 depicted in Figures 11A and 14A and downstream of the SpCas9 ORF in SIN-AAV SpCas9 ver. 2 depicted in Figures 11B and 14B.

[000184] SEQ ID NO: 5493 is the sequence for AAV-R838H.

[000185] SEQ ID NOs: 5494-5505 show sample sgRNA backbone sequences that SaCas9 is complexed with.

[000186] SEQ ID NO: 5506 is the AAV sequence in pSIA0l2.

[000187] SEQ ID NO: 5507 is the AAV sequence in pSIA0l5.

[000188] SEQ ID NO: 5508 is the AAV sequence in SIN-AAV-SpCas9 version 1 (GRK1).

[000189] SEQ ID NO: 5509 is the AAV sequence in SIN-AAV-SpCas9 version 2 (GRK1).

[000190] SEQ ID NO: 5510 is the AAV sequence in SIN-AAV-SpCas9 version 1 (sEFla).

[000191] SEQ ID NO: 5511 is the AAV sequence in SIN-AAV-SpCas9 version 2 (sEFla).

[000192] SEQ ID NO: 5512 is a plasmid sequence for pSpCas9 (BB)-2A-miRFP670

(“pSpCas9”).

[000193] SEQ ID NO: 5513 is a spacer sequence for a gRNA or sgRNA encoded by pSIA003 from Examples 32-34.

[000194] SEQ ID NO: 5514 is pSIA022, a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5274.

DETAILED DESCRIPTION

[000195] Applicants have discovered a novel method for treating an autosomal dominant CORD, e.g., a CORD associated with a mutation in a GUCY2D gene. The method can result in slowing the development of CORD or preventing development of disease in an individual. Applicants have also discovered a self-inactivating CRISPR/Cas system.

[000196] Therapeutic approach

[000197] The methods provided herein, regardless of whether a cellular, ex vivo or in vivo method can involve one or a combination of the following methods. One method involves reducing or eliminating expression of a GUCY2D allele containing a mutation (e.g., an R838H, R838C, or R838S mutation) at the protein level using non-homologous end joining (NHEI) to introduce a frameshift mutation in the R838H, R838C, or R838S mutant allele. The frameshift can be caused by an insertion or deletion that arises during NHEI. In another method, a mutant allele (e.g., an R838H, R838C, or R838S mutation) is corrected by HDR. A third method includes knocking-in GUCY2D cDNA into a GUCY2D gene locus or into a safe harbor locus. [000198] The NHEJ frameshifting strategy can involve inducing one single stranded break or double stranded break within or near the R838H, R838C, or R838S mutation in the GUCY2D gene with one or more CRISPR endonucleases and a gRNA (e.g., crRNA + tracrRNA, or sgRNA), or two or more single stranded breaks or double stranded breaks within or near the R838H, R838C, or R838S mutation in the GUCY2D gene with two or more CRISPR endonucleases and two or more sgRNAs. This approach can prevent the trasncription/synthesis of the R838H, R838C, or R838S mutatant allele by causing a frameshift in the R838H, R838C, or R838S mutant allele. This method utilizes gRNAs or sgRNAs specific for the R838H,

R838C, or R838S mutation in the GUCY2D gene.

[000199] The HDR correction strategy can involve inducing one single stranded break or double stranded break within or near the R838H, R838C, or R838S mutation in the GUCY2D gene with one or more CRISPR endonucleases and a gRNA (e.g., crRNA + tracrRNA, or sgRNA), or two or more single stranded breaks or double stranded breaks within or near the R838H, R838C, or R838S mutation in the GUCY2D gene with one or more CRISPR endonucleases (Cas9, Cpfl and the like) and two or more gRNAs, in the presence of a donor DNA template introduced exogenously to direct the cellular DSB response to Homology- Directed Repair. The donor DNA template can be a short single stranded oligonucleotide, a short double stranded oligonucleotide, a long single or double stranded DNA molecule. The methods can provide gRNA pairs that make a deletion by cutting the gene twice, one gRNA cutting at the 5’ end of the R838H, R838C, or R838S mutation and the other gRNA cutting at the 3’ end of the R838H, R838C, or R838S mutation that facilitates insertion of a new sequence from a polynucleotide donor template to replace the R838H, R838C, or R838S mutation in the GUCY 2D gene. The cutting can be accomplished by a pair of DNA endonucleases that each makes a DSB (one DSB on each end of the R838H, R838C, or R838S mutation), or by multiple nickases that together make a DSB (one DSB on each end of the R838H, R838C, or R838S mutation). This method utilizes gRNAs or sgRNAs specific for the R838H, R838C, or R838S mutation in the GUCY2D gene and donor DNA molecules.

[000200] The knock-in strategy involves knocking -in GUCY2D cDNA into the GUCY2D gene locus using a gRNA (e.g., crRNA + tracrRNA, or sgRNA) or a pair of gRNAs targeting upstream of or in the first or other exon and/or intron of the GUCY2D gene, or in a safe harbor site (such as AAVS1). The donor DNA can be single or double stranded DNA.

[000201] The advantages for the above strategies (frameshift, correction, and knock-in) are similar, including in principle both short and long term beneficial clinical and laboratory effects. The knock-in approach provides at least one advantage over the frameshift and correction approach - the ability to treat all patients versus only a subset of patients.

[000202] Such methods use endonucleases, such as CRISPR-associated (Cas9, Cpfl and the like) nucleases, to stably correct the R838H, R838C, or R838S mutation within the genomic locus of the GUCY2D gene. Any CRISPR endonuclease can be used in the methods of the present disclosure, each CRISPR endonuclease having its own associated PAM, which can or cannot be disease specific. For example, gRNA spacer sequences for targeting the R838H, R838C, or R838S mutation in the GUCY2D gene with a CRISPR/Cas9 endonuclease from S. pyogenes or S. aureus have been identified in SEQ ID NOs. 5282-5313, 5398-5409, and 5434- 5443 of the Sequence Listing.

[000203] Examples set forth in the present disclosure can induce single stranded breaks or double stranded breaks within or near the R838H, R838C, or R838S mutation in the GUCY2D gene to introduce a frameshift or correct the R838H, R838C, or R838S mutation within the GUCY 2D gene with as few as a single treatment (rather than deliver potential therapies for the lifetime of the patient).

[000204] Cone-Rod Dystrophy (CORD)

[000205] Cone rod dystrophies (CORD) are a group of inherited retinal dystrophies characterized by retinal pigment deposits predominantly localized in the macular region. CORD leads to primary degeneration of cones followed by loss of rods and has a prevalence of 1 :40,000 (Garcia-Hoyos et ak, 2011, Molecular Vision; Mukheqee et ak, 2014, Eye, 28:481-487). Some forms of CORD have been observed to be inherited as an autosomal dominant, autosomal recessive or X-linked recessive trait while others occur spontaneously. Onset of the disease normally occurs in the first two decades of life. There are four major causative genes involved in CORD: ABCA4 (causing 30-60% of all autosomal recessive CORDs), CRX and GUCY2D (responsible for 35% of autosomal dominant CORDs / cone dystrophies), and RPGR (causing X- linked CORDs). All GUCY2D gene mutations in patients with autosomal dominant CORD are located at codon 838 or the two adjacent codons 837 and 839, leading to degeneration of photoreceptors and visual deterioration (Mukheqee et ak, 2014, Eye, 28:481-487; Kitiratschky et ak, 2008, Science, 49: 5015-5023). Mutations in the GUCY2D gene account for 20% of all CORD disease. Mutations in codon 838 account for up to 95% of all mutations in the GUCY2D gene leading to photoreceptor degeneration due to the mutated RetCG-l protein. In the US itself there are 1,500 patients with codon 838 mutations in the GUCY2D gene (Garcia-Hoyos et ak, 2011, Molecular Vision 17: 1103-1109; Mukheqee et ak, 2014, Eye, 28:481-487; Kitiratschky et al., 2008, Science, 49: 5015-5023), with 19 new patients per year (Hamel et al., 2006, Orphanet Journal of Rare Diseases 2: 1-7).

[000206] A hallmark of CORDs is retinal pigment deposits visible on fundus examination, predominantly localized in the macular region (Hamel et al., 2006, Orphanet Journal of Rare Diseases 2: 1-7). Most CORD patients display the following symptoms: decreased central vision, color vision defects, photophobia and decreased sensitivity in the central field at early stages, followed by progressive loss in peripheral vision and night blindness at later stages. The clinical course of CORDs is generally more severe and rapid than of rod cone dystrophies, leading to earlier legal blindness and disability (Hamel et al., 2006, Orphanet Journal of Rare Diseases 2: 1-7; Mukheqee et al., 2014, Eye, 28:481-487). Non syndromic CORDs are genetically heterogenous and may be inherited as autosomal dominant, autosomal recessive, or X-linked trait (Mukherjee et al., 2014, Eye, 28:481-487).

[000207] CORD can cause a variety of symptoms that include decreased central visual acuity and photophobia which is a reduced ability to see colors and an increased sensitivity to light, both of which are the first symptoms to appear in the first decasde of life, followed by night blindness and further decrease of visual acuity. CORD can be divided into two groups, stationary CORD in which symptoms remain stable and are mostly present at birth or early childhood, and progressive CORD in which symptoms slowly become worse over time, so that a person is considered legally blind with a visual acuity that is 20/200 or worse. Progression of CORD is generally more severe and rapid than rod cone dystrophy (e.g. retinitis pigmentosa), leading to earlier blindness. Total blindness is not common in individuals affected with cone dystrophy and peripheral vision is usually unaffected. Affected individuals can see well at night or under conditions of low light as the rod cells are usually unaffected. Key endpoints to assess treatment related outcomes include measuring visual acuity, electroretinography response, optical coherence tomography and patient reported outcome.

[000208] CORD caused by a R838H, R838C, or R838S mutation in a GUCY2D gene is a monogenic disorder with autosomal dominant inheritance. If a patient only has one R838H, R838C, or R838S mutant allele, a frameshift can be introduced into one R838H, R838C, or R838S mutant allele per cell to prevent the transcription/synthesis of the one R838H, R838C, or R838S mutant allele. A novel approach has been discovered for ameliorating the effects of autosomal dominant CORD by introducing a frameshift into one R838H, R838C, or R838S mutant allele per cell to prevent the transcription/synthesis of the one R838H, R838C, or R838S mutant allele. [000209] Also, if a patient only has one R838H, R838C, or R838S mutant allele, the one R838H, R838C, or R838S mutant allele can be corrected to restore RetGCl function. If a patient has two R838H, R838C, or R838S mutant alleles, both R838H, R838C, or R838S mutant alleles can be corrected with HDRto restore RetGCl function.

[000210] Introducing a frameshift into a R838H, R838C, or R838S mutant allele or correcting a R838H, R838C, or R838S mutant allele using gene editing provides an important improvement over existing or potential therapies, such as introduction of RetGC 1 expression cassettes through lentivirus delivery and integration because of its preciseness and lower adverse effects.

[000211] Guanylate Cyclase 2D (GUCY2D) gene

[000212] The GUCY2D gene spans a sequence of approximately 17.7 kb, ranges from

8,002,594 - 8,020,339 bp, and encodes for the protein retinal membrane guanylate cyclase-l (RetGCl) that functions in the maintenance of normal vision and is located within the photoreceptors (expressed in both rod and cone photoreceptors) in the retina. The protein is predominantly expressed in cone outer segments and has a molecular weight of 120 Kd. The GUCY2D cDNA consists of 3641 nucleotides, spanning 17.7 kb of genomic DNA. RetGC-l takes part in the recovery phase of phototransduction and is located in the marginal region of the cone’s outer segments. RetGC proteins play an important role in restoring photoreceptor sensitivity due to their involvement in the synthesis of cGMP, and regulate the calcium level in cells. Once light enters the eye, it stimulates specialized pigments in photoreceptor cells which further trigger a series of chemical reactions that produce an electrical signal. This electrical signal is decoded by the brain as vision. Following stimulation, the photoreceptors return to their resting state and await the next round of stimulation. RetGC-l protein takes part in a chemical reaction that helps return photoreceptors to their resting state after light exposure (Boye, 2016, Advances in Experimental Medicine and Biology). Light stimulates the degradation of cGMP, causing the closing of cation channels, which results in cell hyperpolarization and

neurotransmitter release. At lower concentration, calcium stimulates RetGCs and as a consequence the cGMP level is restored. As a result, the cation channels reopen and

photosensitivity is restored to the cell (Garcia-Hoyos et ah, 2011, Molecular Vision 17: 1103- 1109).

[000213] So far, several identified GUCY2D mutations in CORD patients are located at the codon 838 or the two adjacent ones 837, and 839 (Mukheqee et ah, 2014, Eye, 28:481-487; Garcia-Hoyos et ah, 2011, Molecular Vision 17: 1 103-1109). R838X mutations and adjacent mutations induce a gain of function of RetGC-l leading to higher calcium concentration and inducing photoreceptor degeneration (Garcia-Hoyos et al., 2011, Molecular Vision 17: 1103- 1109; Mukheqee et al., 2014, Eye, 28:481-487; Hamel et al., 2007, Orphanet Journal of Rare Diseases). Until now, several identified GUCY2D mutations in CORD patients are located at codon 838 or the two adjacent codons 837 and 839 (Mukheqee et al., 2014, Eye, 28:481-487; Garcia-Hoyos et al., 2011, Molecular Vision 17: 1 103-1109) leading to degeneration of photoreceptors and visual deterioration. These mutations produce a gain of function in increasing the affinity of the RetGC- 1 for the guanylate cyclase activating proteins even in high calcium concentration, leading to a higher cGMP concentration (Mukheqee et al., 2014, Eye, 28:481-487; Garcia-Hoyos et al., 2011, Molecular Vision 17: 1103-1109; Weigell-Weber et al., 2000, Archives of Ophthalmology; Van Ghelue et al., 2000, Ophthalmic Genetics; Wilkie et al., 2000, Human Molecular Genetics). The photoreceptor death is believed to be caused by the high cGMP concentration keeping cGMP -gated cation channel open, resulting in an increased calcium concentration in the cell (Mukheqee et al., 2014, Eye, 28:481-487; Tucker et al., 1999,

Proceedings of the National Academy of Sciences, 96:9039-9044).

[000214] GUCY2D can also be referred to as GUC1A4; RCD2; LCA1; GUC2D; retGC;

LCA; ROSGC; CYGD; RETGC- 1; CORD6; ROS-GC1; RETGC; CORD5; RETGC 1; Guanylate Cyclase 2D, Membrane (Retina-Specific); Rod Outer Segment Membrane Guanylate Cyclase; Guanylate Cyclase 2D, Retinal; Retinal Guanylate Cyclase 1; Cone Rod Dystrophy 6; EC 4.6.1.2; RETGC- 1; GUC1A4; ROS-GC; RetGC; CORD6; GUC2D; EC 4.6.1; ROS-GC1;

RETGC 1; CORD5; ROSGC; CYGD; LCA1; RCD2; LCA. GUCY2D has a cytogenetic location of 17r13.1 and the genomic coordinates as seen on Ensembl database are on Chromosome 17 on the forward strand at position 8,002,594-8,020,339. A nucleotide sequence of GUCY2D is shown as SEQ ID NO: 5266. RP11-1099M24.8 is the gene upstream of GUCY2D on the forward strand and ALOX15B is the gene downstream of GUCY2D on the reverse strand. Contained within the GUCY2D gene is the gene RP11-474L23.3 on the reverse strand. The gene RP11-1099M24.9 is located on the reverse strand opposite of GUCY2D. GUCY2D has a NCBI gene ID of 3000, Uniprot ID of Q02846 and Ensembl Gene ID of ENSG00000132518. GUCY2D has 1,684 SNPs, 19 introns and 20 exons. The exon identifier from Ensembl and the start/stop sites of the introns and exons are shown in Table 1. Table 1. Exons and Introns for GUCY2D

[000215] Table 2 provides information on all of the transcripts for the GUCY2D gene based on the Ensembl database. Provided in Table 2 are the transcript ID from Ensembl and

corresponding NCBI RefSeq ID for the transcript, the translation ID from Ensembl and the corresponding NCBI RefSeq ID for the protein, the biotype of the transcript sequence as classified by Ensembl and the exons and introns in the transcript based on the information in Table 1. Table 2. Transcript Information for GUCY2D

[000216] GUCY2D has 1,684 SNPs and the NCBI rs number and/or UniProt VAR number for the SNPs of the GUCY2D gene are rs2534, rs28l6, rs38l3585, rs3829789, rs389l083, rs392873 l, rs479l452, rs479l456, rs4792l l l, rs7406l06, rs750l868, rs75039l8, rs8068722, rs8069344, rs807H66, rs98896l2, rs989H37, rs989l2l9, rs9905393, rs9905402, rs99l2l76, rs99l43 l5, rs99l4686, rs99l4937, rsl l655487, rsl l65569l, rsl2l0347l, rsl2l035 l9, rsl2l0352l, rsl24498l4, rsl2602083, rs2874302l, rs28933695, rs339l43 l4, rs33942683, rs340l6036, rs340498l8, rs34065746, rs3433l388, rs34463l60, rs34466558, rs34594470, rs34596269, rs34598902, rs3467l9l9, rs34922798, rs35134646, rs35146471, rs35357335, rs356l6384, rs3588l05 l, rs35883 l05, rs55687426, rs559l6957, rs56034424, rs56056557, rs56l30505, rs5628023 l, rs563 l6238, rs56348l43, rs57l8407l, rs572733 l0, rs58765829, rs60l30989, rs6l749663, rs6l749664, rs6l749665, rs6l749667, rs6l749668, rs6l749669, rs6l749670, rs6l74967l, rs6l749672, rs6l749673, rs6l749674, rs6l749675, rs6l749676, rs6l749677, rs6l749678, rs6l749679, rs6l749680, rs6l74968l, rs6l749682, rs6l749683, rs6l749753, rs6l749754, rs6l749755, rs6l749756, rs6l749758, rs6l749759, rs6l750l60, rs6l750l6l, rs6l750l62, rs6l750l63, rs6l750l64, rs6l750l66, rs6l750l67, rs6l750l68, rs6l750l69, rs6l750l70, rs6l750l7l, rs6l750l72, rs6l750l73, rs6l750l74, rs6l750l75, rs6l750l76, rs6l750l77, rs6l750l78, rs6l750l79, rs6l750l80, rs6l750l8l, rs6l750l82, rs6l750l83, rs6l750l84, rs6l750l85, rs6l750l86, rs6l750l87, rs6l750l88, rs6l750l89, rs6l750l90, rs6l750l92, rs6l750l93, rs6l750l94, rs6l750l96, rs6l750l97, rs6l750l98, rs6l750l99, rs62065069, rs62065070, rs6264l254, rs63340060, rs63749076, rs63749078, rs67594392, rs72203439, rs7284l478, rs7284l480, rs7284l48l, rs7284l482, rs73237655, rs73244l90, rs7397865 l, rs73978652, rs73978653, rs73978654, rs73978655, rs73978656, rs73978658, rs73978659, rs74579703, rs74656480, rs74864625, rs75290069, rs758376l6, rs76l96l20, rs76459l65, rs77430877, rs77752392, rs779229l5, rs78l 17741, rs78380494, rs78434534, rs7876l797, rs78844078, rs7890l930, rs7890875 l, rs7928886l, rs79347759, rs7958l544, rs798872l2, rs79980H9, rs80076597, rs80245692, rsl 12085163, rsl 12360110, rsl 12372281, rsl 12764660, rsl 12923697, rsl 12984002, rsl 13031167, rsl 13153323, rsl 13332317, rsl 15598390, rsl 16236245, rsl 16728094, rsl 16841812, rsl 16870332, rsl 17241209, rsl 17853745, rsl 18026892, rsl 18057940, rsl 18102619, rsl 18140564, rsl37853897, rsl38l62268, rsl38l76835, rsl38200238, rsl38255027, rsl38298l87, rsl38596240, rsl38635 l98, rsl38836357, rsl38869083, rsl389224l5, rsl390l9420, rsl39046650, rsl39l68077, rsl396l6l84, rsl3973l548, rsl39763939, rsl40005435, rs 140366544, rsl40436048, rsl40628227, rsl40638938, rsl40657975, rsl4066l2l8, rsl408896l2, rsl40936694, rsl4099l876, rsl4l2l4l99, rsl4l229863, rsl4l346556, rsl4l352623, rsl4l360883, rsl4l59265 l, rsl4l837808, rsl4l9l7297, rsl4l956583, rsl4l967896, rsl42050758, rsl42207894, rsl42275378, rsl4235 l773, rsl42368822, rsl424l552l, rsl42997995, rsl43323 l76, rsl43524082, rsl4353579l, rsl43585840, rsl43604l2l, rsl43607596, rsl43650826, rsl43730352, rsl43745703, rsl4376l257, rsl43938678, rsl44l5 l076, rsl4429l605, rsl44349779, rsl44442H5, rsl44458688, rsl44565 l68, rsl44659l3 l, rsl45060888, rsl4534408l, rsl45420245, rsl457l7676, rs 146031822, rsl46l49224, rsl46406238, rsl46570l35, rsl46820642, rsl46849545, rsl46855363, rsl46872553, rsl470l7233, rsl47l64228, rsl47l66962, rsl4720l985, rsl474l06l7, rsl4758606l, rsl47656459, rsl48l362l3, rsl4839458l, rsl48448937, rsl48624438, rsl4876l225, rsl4887l664, rsl48924873, rsl48987l06, rsl49l49530, rsl492600l l, rsl49314785, rsl49560l34, rsl49722832, rsl49866657, rsl50l73998, rsl50l85423, rsl50422660, rsl50742659, rsl50797l98, rsl51052136, rsl51079263, rsl51106252, rsl51126238, rsl51268449, rsl51330485, rsl8074064l, rsl8079623l, rsl 80896227, rsl8l3562l3, rsl8l5664l0, rsl8l567056, rsl8l8006l0, rsl82l05834, rsl82237936, rsl82456792, rsl83308730, rsl8333l808, rsl83393377, rsl83480892, rsl83556945, rsl8356l005, rsl84l30l07, rsl84l5l004, rsl84l64679, rsl84234997, rsl 84286345, rsl847259l0, rsl848H496, rsl85088930, rsl85 l5720l, rsl855 l3239, rsl85569607, rsl857l3 H5, rsl859202l6, rsl86268358, rsl86335397, rsl86508466, rsl 86802043, rsl8682686l, rsl86938529, rsl87098034, rsl874999l5, rsl87668l00, rsl8776l992, rsl878332l9, rsl87834l38, rsl87999872, rsl88568530, rsl88638994, rsl88708948, rsl88779H4, rsl89065870, rsl89l4l326, rsl89l8302l, rsl89559705, rsl896050l5, rsl89807747, rsl89930296, rsl89984380, rsl90283426, rsl90420345, rsl904682l5, rsl90680904, rsl90700778, rsl9085l646, rsl9l 165076, rs 191204702, rsl9l332697, rsl9l576243, rsl9l8l8936, rsl9l907268, rsl92007830, rsl92059023, rsl92306625, rsl92765 l08, rsl92836968, rsl928595 l4, rsl93175998, rsl932l2053, rsl996l 1541, rsl997083l2, rsl998l7768, rsl99828903, rsl99835050, rsl999l2675, rsl9993 H93, rsl99953653, rsl99966203, rs200032594, rs200128473, rs200l89360, rs2002H3 l5, rs2002l5575, rs20024l2l8, rs200403362, rs200558780, rs200586401, rs200637525, rs20065 l999, rs200700723, rs2007054l7, rs200855025, rs200886585, rs201008187, rs201054971, rs20l090802, rs20l 119605, rs20l 196538, rs201294458, rs20l3 l9533, rs20l383207, rs20l388569, rs20l4l4567, rs20l54l863, rs20l587670, rs20l656l08, rs20l7l7870, rs201897109, rs202094l05, rs202l 11469, rs202l32636, rs267606857, rs281865408, rs281865409, rs28l8654l0, rs28l8654l 1, rs28l8654l2, rs28l8654l3, rs367660008, rs3677l 1120, rs367755752, rs367767l 19, rs367817490, rs36830l973, rs36833030l, rs368349l86, rs368384232, rs368480652, rs368557900, rs368799458, rs3689l6l22, rs36892372l, rs368944056, rs368945604, rs368958527, rs369035095, rs369222553, rs369247789, rs3693 l58l4, rs369527655, rs369547545, rs369607l37, rs369663256, rs369920240, rs370054772, rs370l66526, rs37029l650, rs370295773, rs370303747, rs370306654, rs370318503, rs370350737, rs3706073 l8, rs370725838, rs370742l62, rs370833664, rs3709l67l9, rs37l 160436, rs37l 176908, rs37l3228l2, rs37l367958, rs37l458632, rs37l53397l, rs37l54l944, rs371565742, rs37l677282, rs37l7l8267, rs37l908939, rs37l9l99l2, rs37l952237, rs372005 l26, rs3720l 1559, rs372093845, rs372H869l, rs372l5l247, rs372l8903 l, rs374354l68, rs374464654, rs3750l073 l, rs375105072, rs375259l85, rs375319109, rs375424336, rs375428889, rs375468242, rs375574l 16, rs375686386, rs375727l97, rs375760706, rs37585 l554, rs376006766, rs376062280, rs376076l 12, rs376337508, rs376364350, rs376439753, rs376468724, rs376479795, rs376508683, rs37660l845, rs3766l5794, rs376759049, rs37686l829, rs376929203, rs376992406, rs37702l 127, rs377l03968, rs377l99837, rs377279983, rs377287956, rs3749697l3, rs374927l50, rs374924527, rs374800328, rs3746795l8, rs374658427, rs374636320, rs374580575, rs374566845, rs3745206l9, rs374515716, rs374507808, rs374507426, rs374505063, rs374l384l6, rs374065209, rs37403 l99l, rs373866646, rs373827556, rs373788984, rs373767265, rs3736l5436, rs373533477, rs373468027, rs373400629, rs373362030, rs373357l65, rs3730l028l, rs372902332, rs37265 l6l4, rs37263l047, rs3725436l2, rs372437l3l, rs377299382, rs377349549, rs37738803 l, rs3775579l 1, rs377568220, rs377594823, rs3776l7525, rs377622295, rs377648l85, rs377650l96, rs386834239, rs397700887, rs398l23233, rs527329237, rs5275420l3, rs527646004, rs527659830, rs527767509, rs528l69554, rs528203345, rs528258925, rs52879l875, rs528826742, rs5290376l2, rs529l805 l4, rs52923282l, rs529348303, rs529594203, rs5296l5 l33, rs529702465, rs529726426, rs529993769, rs530057359, rs530l85073, rs5302096l3, rs53032802l, rs531023711, rs531091295, rs53 l2l7355, rs53 l378l85, rs531556241, rs531612488, rs531669033, rs531693520, rs531982313, rs532l42507, rs532l53534, rs532339805, rs532388657, rs532466020, rs532577225, rs532826586, rs533083983, rs533311236, rs533407l 12, rs533940473, rs534022358, rs534l95509, rs534270598, rs534452349, rs534482693, rs5345055l9, rs53459l759, rs535329733, rs53536524l, rs5353734l9, rs535800696, rs535966503, rs535982563, rs5360H574, rs536530l82, rs53673 l863, rs536792434, rs536803598, rs5368054l0, rs537l2796l, rs537485807, rs537729498, rs53775720l, rs537797l03, rs53792870l, rs537953527, rs537992694, rs5380006l8, rs538l6l935, rs538470494, rs5387l9629, rs538856385, rs5390l4522, rs539l 10487, rs5393800l3, rs539468342, rs539558334, rs539723740, rs53979707l, rs539967957, rs540l 18139, rs540262740, rs5404l4225, rs540448686, rs540833632, rs540877234, rs540877830, rs540911894, rs540943749, rs54l055967, rs54l07354l, rs541299023, _rs 541449650, rs54l537384, rs54l807865, rs54l84l 155, rs541897718, rs542322730, rs542436l90, rs542466976, rs542520858, rs542570988, rs542720789, rs54292228l, rs54332974l, rs543370993, rs543456744, rs543802677, rs5439l908l, rs543940794, rs54407l266, rs544365402, rs544368608, rs5444l05 l8, rs5444l0836, rs544448494, rs544905777, rs544938l22, rs545104656, rs54527l894, rs545349538, rs545438074, rs545438l23, rs5460l6309, rs546260863, rs54632342l, rs546376402, rs5477784l5, rs547846849, rs547867709, rs547885527, rs547968529, rs548079477, rs548l6l4l4, rs548396303, rs548756390, rs548929399, rs548945470, rs549l00277, rs549l42397, rs54983485 l, rs549995044, rs550028l83, rs550073930, rs550l07422, rs55085747l, rs5509l5 l96, rs550992644, rs550996386, rs551078742, rs551592000, rs551713029, rs551724597, rs551798084, rs552064079, rs552184470, rs552697544, rs552738572, rs55285069l, rs54744l462, rs547112247, rs546983953, rs546875049, rs546466375, rs5464l70l0, rs54637833 l, rs552923753, rs553072849, rs553310926, rs553602736, rs553760068, rs553793 l63, rs553866555, rs553908583, rs554046976, rs554078433, rs554409602, rs55445 l844, rs554782032, rs5550352l0, rs555042960, rs555455408, rs55557l688, rs55583572l, rs555903665, rs555980737, rs556070337, rs556242786, rs556306222, rs556306503, rs556475744, rs556748323, rs557073963, rs557l08466, rs55724l953, rs557387508, rs557434200, rs55746l086, rs5576l063 l, rs558084054, rs558l826l4, rs558202780, rs55823 l853, rs558292964, rs558294899, rs558330360, rs558513244, rs558953933, rs559l02087, rs559483603, rs559542629, rs559924290, rs560225721, rs560270873, rs560366032, rs560379930, rs560407738, rs560476l39, rs560548493, rs56l3 l8435, rs56l600004, rs56l7l5780, rs562248093, rs5622655 l6, rs562446256, rs562578337, rs562580870, rs562685254, rs562730568, rs5627946l6, rs56293 l2l0, rs562955779, rs563005 l5 l, rs5630l4439, rs56309l520, rs563093 l47, rs563208 l76, rs563600965, rs563639504, rs563773522, rs563790636, rs563853837, rs563889760, rs564138931, rs564461174, rs564535411, rs564575395, rs564644984, rs564809875, rs564839085, rs5648685 l0, rs564922369, rs565045308, rs565490655, rs56568392l, rs565948960, rs56627l985, rs566465559, rs566728 l83, rs566769575, rs56689l487, rs566928694, rs566944947, rs566953664, rs56698652l, rs5672944l4, rs567308384, rs5674020l5, rs567463643, rs56765 l225, rs5677087l0, rs56806l033, rs56822039l, rs568227769, rs56824l298, rs568389697, rs56872595 l, rs569l33278, rs569288698, rs569335925, rs569363032, rs569378426, rs569402782, rs5696l3224, rs569618690, rs57025 l6l9, rs570326099, rs5703298 l3, rs570604735, rs570648500, rs57l077663, rs57l 108752, rs57l236000, rs57l3598 l5, rs57l420864, rs57l522042, rs57l876720, rs57l940488, rs572l665 l9, rs5722l4888, rs572363 l36, rs572527369, rs572687257, rs573270795, rs573367793, rs573405328, rs573455326, rs5734656l7, rs5737l5 l07, rs57388357l, rs574106259, rs574248 l8 l, rs574350498, rs574862256, rs574872059, rs574894754, rs574926836, rs575137886, rs575674l7l, rs575870524, rs576l8 l574, rs576275667, rs5767l9987, rs576720l62, rs5770H007, rs577023 l75, rs577407924, rs57772092l, rs577797978, rs577800522, rs577806343, rs577880l64, rs577906096, rs5779l8795, rs5782l643 l, rs745306850, rs74530686l, rs7454l9505, rs745426085, rs745444949, rs745511852, rs745533728, rs74555 l727, rs7456l80l8, rs745627220, rs7457l0l83, rs74576l477, rs7458 l62l9, rs7458 l6355, rs745882425, rs74589047l, rs745897683, rs745956207, rs745956774, rs745965625, rs74600287l, rs746020263, rs746058533, rs746068022, rs746l50760, rs746244895, rs746245709, rs746326l56, rs74636l 123, rs746387733, rs746463069, rs746477554, rs7465253 l6, rs74663 l257, rs74667l374, rs746733885, rs746760406, rs746769693, rs74680680l, rs746827007, rs746859702, rs746883969, rs746893543, rs746924059, rs746947825, rs747008057, rs747038879, rs74709596l, rs747098258, rs747l48534, rs747l73302, rs74730048l, rs747338l44, rs747342259, rs7473540l6, rs747387l96, rs74739H69, rs747534233, rs747611318, rs74764649l, rs747660548, rs747728750, rs747733556, rs747807494, rs747809048, rs747899948, rs747948522, rs74795 l577, rs7479536l2, rs7480l3570, rs748043 l3 l, rs748156659, rs748202022, rs748255432, rs74830l943, rs748509676, rs748520738, rs7485647l8, rs748588464, rs748653489, rs748665297, rs748677206, rs748789502, rs748798324, rs748817525, rs748820854, rs74894690l, rs749012764, rs749084260, rs749l0l279, rs749l38289, rs749l64572, rs749240455, rs749314383, rs7494320l2, rs7494359l8, rs749436007, rs74946342l, rs749511762, rs749535904, rs74960777l, rs74962l660, rs74965l87l, rs749736899, rs749800225, rs749863 l95, rs7499l20l8, rs7499660l0, rs74999l246, rs749999803, rs750005559, rs750007435, rs750l53057, rs750247l23, rs75030l530, rs750336532, rs750399742, rs750399947, rs750453350, rs750454050, rs750484873, rs750566089, rs750572766, rs750635086, rs750668023, rs750743574, rs750889782, rs750895890, rs750904732, rs750906839, rs750967765, rs751090137, rs751132098, rs751263915, rs751295073, rs751340355, rs751389375, rs751520851, rs751582497, rs751705225, rs751794453, rs751802666, rs75 l8H525, rs751822337, rs751882664, rs751992560, rs751995887, rs752037l 12, rs752057528, rs752088799, rs752l4l508, rs752l46300, rs752269926, rs752327486, rs7524204l4, rs75252l534, rs752607737, rs752627946, rs7527l50l5, rs752736704, rs75275 l984, rs752758326, rs75278436l, rs752804462, rs7528l298l, rs752820485, rs752935089, rs752946790, rs752996693, rs753057356, rs753l642l l, rs753l66398, rs753166496, rs753167035, rs753220l25, rs753282322, rs75329l5 l5, rs753328828, rs7534450l9, rs753447830, rs753468278, rs753488664, rs753507l83, rs753600757, rs753620l l l, rs753660903, rs7537504l7, rs753766842, rs753855098, rs753886745, rs753928228, rs754025464, rs754l34l76, rs754l70292, rs754l70656, rs754l93560, rs754266653, rs754274583, rs754320374, rs75432990l, rs75443 l996, rs754473375, rs75458l545, rs754709344, rs7547l7527, rs754747609, rs75480004l, rs754833828, rs75484l 103, rs754869603, rs754954638, rs754964975, rs75497863l, rs755056200, rs75507l207, rs755072380, rs755088085, rs755 l50485, rs755l84357, rs755223 l58, rs755324667, rs755329222, rs7554l4746, rs75545453 l, rs755464893, rs755515660, rs755519877, rs755548l92, rs755696l77, rs755696904, rs755768308, rs755787827, rs755908l64, rs755999834, rs75603l060, rs75603 l378, rs756042293, rs75604248l, rs756044745, rs756l2l043, rs756l23 l57, rs756l35232, rs7562l0907, rs756319569, rs756393266, rs756464199, rs756464730, rs756478965, rs756575304, rs756639026, rs756677l63, rs756693094, rs75669537l, rs756730335, rs756733337, rs756787049, rs75685 l759, rs75704l6l 1, rs757l04555, rs757l5893 l, rs757230483, rs757250994, rs75725 H93, rs757257247, rs757259H5, rs75727304l, rs757310094, rs757387072, rs757466277, rs757508954, rs757525 l65, rs757589496, rs757657345, rs757720386, rs757724509, rs757823463, rs7578354l9, rs75787l358, rs757884734, rs757925587, rs757948866, rs757949564, rs758113854, rs758260297, rs7583269l6, rs758442320, rs758522855, rs758602959, rs758629545, rs758645364, rs758659507, rs758775976, rs75884l 128, rs75893 l689, rs7589393 l0, rs75894l038, rs758982450, rs7590l 1004, rs7590756l9, rs759l35596, rs759l58538, rs759l73 H5, rs759220063, rs759253 l67, rs759280279, rs759370090, rs75950l5 l5, rs759511711, rs759516562, rs759544l56, rs759562l74, rs759564l56, rs7596l9l80, rs759723474, rs75973 l2l l, rs759777872, rs759778209, rs759948249, rs759949982, rs75995 l639, rs759957436, rs7600l6257, rs760l055 l5, rs760107054, rs760126408, rs760126540, rs760l26924, rs760l79252, rs760202269, rs760285694, rs760307098, rs760397638, rs760426420, rs760472338, rs760494327, rs76050l583, rs76052l77l, rs760662744, rs76068 l687, rs760765585, rs760766230, rs760877l46, rs760937l97, rs760943859, rs76l03995 l, rs76H53 l88, rs761200249, rs76l2l3 H2, rs76l309365, rs76l4080l0, rs761445993, rs76l448586, _rs 761484472, rs76l498977, rs76l513763, rs761529451, rs761542444, rs76l543634, rs76l63 l03 l, rs761751647, rs761796768, rs761828482, rs76l8596l l, rs76l882804, rs76l9l3009, rs76l9l4605, rs76l934425, rs76l968706, rs762006599, rs762l25685, rs7622l 1580, rs762226529, rs762283787, rs762303998, rs762483687, rs762546467, rs762570628, rs762582573, rs7626l8243, rs762627l 14, rs76277l30l, rs762876977, rs762943482, rs76298 l0l3, rs763034l53, rs763047690, rs763099634, rs763214827, rs763214846, rs763350634, rs763362455, rs76338 l837, rs763389l43, rs763444638, rs763497680, rs763522643, rs763568920, rs763608460, rs763697863, rs7637l27l2, rs763774686, rs763799379, rs76385 H07, rs763859635, rs763890649, rs763907879, rs7639l4758, rs7639450l7, rs764046799, rs76407208 l, rs76409956l, rs764l74l90, rs7642805 l2, rs764286466, rs764334726, rs7643366l3, rs764439l80, rs764473740, rs764522054, rs764579879, rs76459l974, rs764680965, rs7647l582l, rs764749298, rs764794547, rs764858224, rs764905877, rs764907748, rs764954235, rs76499l426, rs765048 l34, rs76505 l553, rs765079532, rs765119055, rs765174065, rs765189820, rs765235904, rs765243245, rs765266637, rs76533 l376, rs765350640, rs765369504, rs76543 l582, rs765432253, rs765439946, rs765463082, rs765520038, rs765682027, rs76577459l, rs7658l28l4, rs76588673 l, rs765906787, rs7659l0207, rs7659l4203, rs7659269l7, rs765964805, rs766l04084, rs766l25236, rs766286225, rs766338743, rs7664l8873, rs7664l890l, rs766422289, rs766482364, rs766557426, rs766570845, rs766640359, rs7666462l7, rs7668222l8, rs766828774, rs766837655, rs766859707, rs766944930, rs76698l529, rs767009640, rs767033042, rs767060337, rs7672l4355, rs767258249, rs767305032, rs767312106, rs767360l20, rs7673920l3, rs76756l967, rs767768l29, rs76777l897, rs7677884l9, rs767799735, rs767800023, rs768080447, rs7680832l0, rs768206746, rs76828454l, rs768365237, rs768390959, rs7684l7052, rs768465375, rs768538403, rs768597548, rs768706642, rs7688l2l25, rs7688l3846, rs7689l5855, rs768994065, rs7690l7393, rs769018282, rs76902306l, rs769024262, rs769069042, rs769129492, rs769214729, rs7692l7873, rs7692l9806, rs769385677, rs76955 l807, rs7695977l6, rs769622690, rs769648456, rs76973 H97, rs7697496l7, rs76980l596, rs769809024, rs7698l854l, rs769964799, rs7700l6889, rs770035607, rs770045903, rs770H95 l3, rs770l48893, rs770164381, rs770l8l308, rs770255396, rs770266H6, rs770358984, rs770374274, rs770484034, rs770512665, rs770587800, rs7707l9238, rs7707400l2, rs770747229, rs770786l8l, rs770873775, rs7709l5628, rs770989683, rs77l0770l6, rs77l080028, rs77l 112679, rs77H3993l, rs771232307, rs771248299, rs77l26l0l2, rs77l288323, rs77l338362, rs771406749, rs771426657, rs77l554986, rs77l64l368, rs77l645454, rs77l698726, rs77l734877, rs77l74l738, rs77l764405, rs77l769796, rs77l806866, rs771962267, rs77205 l9l6, rs772l 12577, rs772l654l9, rs77222l900, rs772228903, rs772230274, rs772235737, rs77224225 l, rs772299l97, rs7723l 1336, rs77244256l, rs772444228, rs772504493, rs772514611, rs772640099, rs772765835, rs772792838, rs772808446, rs772890l93, rs77298624l, rs773030462, rs773037460, rs77307870l, rs7732l 1045, rs773305880, rs7733079l8, rs77332703 l, rs773348446, rs773394059, rs773403637, rs7734l5492, rs773475926, rs773516984, rs773563 l36, rs773787822, rs773808646, rs7738l 1368, rs773849840, rs773886266, rs7739059l6, rs7740l2066, rs774207880, rs774229738, rs774240595, rs774420737, rs774430952, rs774554l2l, rs774560l37, rs77456479l, rs774569l0l, rs774588330, rs7746l5995, rs7746883 l l, rs774767443, rs774868695, rs774903867, rs774923254, rs774925684, rs774934785, rs7749800l6, rs775007490, rs7750440l3, rs775105018, rs775192787, rs775203380, rs775228379, rs775258389, rs775299640, rs775339427, rs775394437, rs7754l5473, rs775550206, rs775635 l96, rs775689438, rs775738l04, rs77582505 l, rs775878558, rs775878637, rs776042543, rs776073853, rs776083430, rs776l52947, rs7762768l3, rs776278329, rs776298636, rs776418340, rs776439H3, rs7764703 l4, rs776563297, rs776624l88, rs776680792, rs776737538, rs776745208, rs776773228, rs776783496, rs776785502, rs776817542, rs776826689, rs776845 l04, rs776893288, rs776947384, rs776974l02, rs7770754l2, rs777l362l7, rs777208445, rs777306l36, rs777336060, rs777397l93, rs777406730, rs777432099, rs777436847, rs777539780, rs777662l87, rs777697046, rs777699097, rs777700238, rs777727222, rs777758286, rs777766926, rs777892234, rs7779547l l, rs777997008, rs778040387, rs778l07598, rs778l77H2, rs7783788l l, rs7786l526l, rs778664525, rs7787l9428, rs778736663, rs778752848, rs7788753 l l, rs77890999l, rs7790l75 l l, rs779l32852, rs779224998, rs77923l833, rs77924l028, rs779246332, rs779286579, rs779327088, rs779428964, rs77943l480, rs779480027, rs779602583, rs779666069, rs779707457, rs779735498, rs779783880, rs779788849, rs779855597, rs779870l73, rs779924630, rs7800l4587, rs780072959, rs7800884l l, rs7802l98l4, rs780266997, rs780323328, rs780368l94, rs780386793, rs78039l826, rs78042646l, rs780449707, rs7805 l0809, rs78053350l, rs78053728l, rs780542223, rs780546534, rs7805509l7, rs780687906, rs780834l62, rs78085845 l, rs780880744, rs7809538l5, rs78095520l, rs7809657l l, rs78l0l02l6, rs78l0l7028, rs78l078843, rs78l l 14491, rs78H3646l, rs78l224455, rs78l230982, rs78l40932l, rs78l4H576, rs78l5 l4479, rs78l53499l, rs78l63572l, rs78l66040l, rs78l678909, rs78l68204l, rs78l725943,

VAR_003437, VAR_009l29, VAR_009l30, VAR_009l3 l, VAR_009l34, VAR_009l35, VAR_0l5373, VAR_023770, VAR_02377l, VAR_042230, VAR_04223l, VAR_067l70, VAR_067l7l, VAR_067l72, VAR_067l74, VAR_067l75, VAR_067l76, VAR_067l77, VAR_067l78, VAR_067l79, VAR_067l80, VAR_067l8l, VAR_067l82, VAR_07l605, VAR_07l606, VAR_07l607, and VAR_07l608.

[000217] There are various mutations associated with CORD, which can be insertions, deletions, missense, nonsense, frameshift and other mutations, with the common effect of inactivating the GUCY2D gene. Any one or more of the mutations can be repaired to restore RetGCl protein activity. For example, the pathological variants, R838H, R838C, or R838S, can be restored or corrected (See Table 3). Table 3

[000218] Exon Deletion

[000219] Another genome engineering strategy involves exon deletion. Targeted deletion of specific exons can be an attractive strategy for treating a large subset of patients with a single therapeutic cocktail. Deletions can either be single exon deletions or multi-exon deletions.

While multi-exon deletions can reach a larger number of patients, for larger deletions the efficiency of deletion greatly decreases with increased size. Therefore, deletions range can be from 40 to 10,000 base pairs (bp) in size. For example, deletions can range from 40-100; 100- 300; 300-500; 500-1,000; 1,000-2,000; 2,000-3,000; 3,000-5,000; or 5,000-10,000 base pairs in size.

[000220] As stated previously, the GUCY2D gene contains 20 exons. Any one or more of the 20 exons can contain a mutation. Any one or more of the 20 mutated exons, or aberrant intronic splice acceptor or donor sites, can be deleted to restore or partially restore the GUCY2D function. In some examples, the methods provide gRNA pairs that can be used to delete any one or more of the mutated exons 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any combinations thereof.

[000221] To ensure that the pre-mRNA is properly processed following deletion, the surrounding splicing signals can be deleted. Splicing donor and acceptors are generally within 100 base pairs of the neighboring intron. Therefore, in some examples, methods can provide all gRNAs that cut approximately +/- 100-3100 bp with respect to each exon/intron junction of interest.

[000222] For any of the genome editing strategies, gene editing can be confirmed by sequencing or PCR analysis.

[000223] In vivo based therapy

[000224] Provided herein are methods for treating a patient with autosomal dominant CORD. In some aspects, the method is an in vivo cell-based therapy. Chromosomal DNA of the cells in the autosomal dominant CORD patient can be edited using the materials and methods described herein. For example, the in vivo method can comprise editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a cell of a patient, such as photoreceptor cells or retinal progenitor cells.

[000225] Although certain cells present an attractive target for ex vivo treatment and therapy, increased efficacy in delivery may permit direct in vivo delivery to such cells. Ideally the targeting and editing would be directed to the relevant cells. Cleavage in other cells can also be prevented by the use of promoters only active in certain cells and or developmental stages. Additional promoters are inducible, and therefore can be temporally controlled if the nuclease is delivered as a plasmid. The amount of time that delivered RNA and protein remain in the cell can also be adjusted using treatments or domains added to change the half-life. In vivo treatment would eliminate a number of treatment steps, but a lower rate of delivery can require higher rates of editing. In vivo treatment can eliminate problems and losses from ex vivo treatment and engraftment.

[000226] An advantage of in vivo gene therapy can be the ease of therapeutic production and administration. The same therapeutic approach and therapy will have the potential to be used to treat more than one patient, for example a number of patients who share the same or similar genotype or allele. In contrast, ex vivo cell therapy typically requires using a patient’s own cells, which are isolated, manipulated and returned to the same patient.

[000227] Ex vivo based therapy

[000228] Provided herein are methods for treating a patient with autosomal dominant CORD. An aspect of such method is an ex vivo cell -based therapy. For example, a patient-specific induced pluripotent stem cell (iPSC) can be created. Then, the chromosomal DNA of these iPSC cells can be edited using the materials and methods described herein. For example, the method can comprise editing within or near a R838H, R838C, or R838S mutation in the GUCY2D gene of the iPSC. Next, the genome-edited iPSCs can be differentiated into other cells, such as photoreceptor cells or retinal progenitor cells. Finally, the differentiated cells, such as photoreceptor cell or retinal progenitor cell, can be implanted into the patient.

[000229] Another aspect of such method is an ex vivo cell-based therapy. For example, photoreceptor cells or retinal progenitor cells can be isolated from the patient. Next, the chromosomal DNA of these photoreceptor cells or retinal progenitor cells can be edited using the materials and methods described herein. For example, the method can comprise editing within or near a R838H, R838C, or R838S mutation in the GUCY2D gene of the photoreceptor cells or retinal progenitor cells. Finally, the genome-edited photoreceptor cells or retinal progenitor cells can be implanted into the patient.

[000230] Another aspect of such method is an ex vivo cell-based therapy. For example, a mesenchymal stem cell can be isolated from the patient, which can be isolated from the patient’s bone marrow or peripheral blood. Next, the chromosomal DNA of these mesenchymal stem cells can be edited using the materials and methods described herein. For example, the method can comprise editing within or near a R838H, R838C, or R838S mutation in the GUCY2D gene of the mesenchymal stem cells. Next, the genome-edited mesenchymal stem cells can be differentiated into any type of cell, e.g., photoreceptor cells or retinal progenitor cells. Finally, the differentiated cells, e.g., photoreceptor cells or retinal progenitor cells can be implanted into the patient.

[000231] One advantage of an ex vivo cell therapy approach is the ability to conduct a comprehensive analysis of the therapeutic prior to administration. Nuclease-based therapeutics can have some level of off-target effects. Performing gene correction ex vivo allows one to characterize the corrected cell population prior to implantation. The present disclosure includes sequencing the entire genome of the corrected cells to ensure that the off-target effects, if any, can be in genomic locations associated with minimal risk to the patient. Furthermore, populations of specific cells, including clonal populations, can be isolated prior to implantation.

[000232] Another advantage of ex vivo cell therapy relates to genetic correction in iPSCs compared to other primary cell sources. iPSCs are prolific, making it easy to obtain the large number of cells that will be required for a cell-based therapy. Furthermore, iPSCs are an ideal cell type for performing clonal isolations. This allows screening for the correct genomic correction, without risking a decrease in viability. In contrast, other primary cells, such as photoreceptor cells or retinal progenitor cells, are viable for only a few passages and difficult to clonally expand. Thus, manipulation of iPSCs for the treatment of autosomal dominant CORD can be much easier, and can shorten the amount of time needed to make the desired genetic correction.

[000233] Genome Editing

[000234] Genome editing refers to the process of modifying the nucleotide sequence of a genome, such as in a precise or pre -determined manner. Examples of methods of genome editing described herein include methods of using site-directed nucleases to cut DNA at precise target locations in the genome, thereby creating single-strand or double-strand DNA breaks at particular locations within the genome. Such breaks can be and regularly are repaired by natural, endogenous cellular processes, such as HDR and NHEJ. These two main DNA repair processes consist of a family of alternative pathways. NHEJ directly joins the DNA ends resulting from a double-strand break, sometimes with the loss or addition of nucleotide sequence, which may disrupt or enhance gene expression. HDR utilizes a homologous sequence, or donor sequence, as a template for inserting a defined DNA sequence at the break point. The homologous sequence can be in the endogenous genome, such as a sister chromatid. Alternatively, the donor can be an exogenous nucleic acid, such as a plasmid, a single-strand oligonucleotide, a double- stranded oligonucleotide, a duplex oligonucleotide or a virus, that has regions of high homology with the nuclease-cleaved locus, but which can also contain additional sequence or sequence changes including deletions that can be incorporated into the cleaved target locus. A third repair mechanism can be microhomology-mediated end joining (MMEJ), also referred to as “Alternative NHEJ (ANHEJ)”, in which the genetic outcome is similar to NHEJ in that small deletions and insertions can occur at the cleavage site. MMEJ can make use of homologous sequences of a few base pairs flanking the DNA break site to drive a more favored DNA end joining repair outcome, and recent reports have further elucidated the molecular mechanism of this process. In some instances, it may be possible to predict likely repair outcomes based on analysis of potential microhomologies at the site of the DNA break.

[000235] Each of these genome editing mechanisms can be used to create desired genomic alterations. A step in the genome editing process can be to create one or two DNA breaks, the latter as double-strand breaks or as two single -stranded breaks, in the target locus as near the site of intended mutation. This can be achieved via the use of site-directed polypeptides, as described and illustrated herein.

[000236] Site-directed polypeptides, such as a DNA endonuclease, can introduce double-strand breaks or single-strand breaks in nucleic acids, e.g., genomic DNA. The double-strand break can stimulate a cell's endogenous DNA-repair pathways [e.g., homology-dependent repair (HDR) or non-homologous end joining (NHEJ) or (ANHEJ) or (MMEJ)]. NHEJ can repair cleaved target nucleic acid without the need for a homologous template. This can sometimes result in small deletions or insertions (indels) in the target nucleic acid at the site of cleavage, and can lead to disruption or alteration of gene expression. The deletions range can be from 40 to 10,000 base pairs (bp) in size. For example, deletions can range from 40-100; 100-300; 300-500; 500-1,000; 1,000-2,000; 2,000-3,000; 3,000-5,000; or 5,000-10,000 base pairs in size. HDR can occur when a homologous repair template, or donor, is available. The homologous donor template can comprise at least a portion of the wild-type GUCY2D gene, or cDNA. The at least a portion of the wild-type GUCY2D gene or cDNA can be exon 1, exon 2, exon 3, exon 4, exon 5, exon 6, exon 7, exon 8, exon 9, exon 10, exon 11, exon 12, exon 13, exon 14, exon 15, exon 16, exon 17, exon 18, exon 19, exon 20, intronic regions, fragments or combinations thereof, or the enitre GUCY2D gene or cDNA. The donor template can be either a single or double stranded polynucleotide. The donor template can be up to 5KB. The donor template can be up to 4KB. The donor template can be up to 3 KB. The donor template can be up to 2 KB. The donor template can be up to 1KB. The donor template can be delivered by AAV. The homologous donor template can comprise sequences that can be homologous to sequences flanking the target nucleic acid cleavage site. For example, the donor template can have homologous arms to the 17r13.1 region. The donor template can also have homologous arms to the pathological variant R838H, R838C, or R838S. The sister chromatid can be used by the cell as the repair template. However, for the purposes of genome editing, the repair template can be supplied as an exogenous nucleic acid, such as a plasmid, duplex oligonucleotide, single-strand oligonucleotide, double-stranded oligonucleotide, or viral nucleic acid. With exogenous donor templates, an additional nucleic acid sequence (such as a transgene) or modification (such as a single or multiple base change or a deletion) can be introduced between the flanking regions of homology so that the additional or altered nucleic acid sequence also becomes incorporated into the target locus. MMEJ can result in a genetic outcome that is similar to NHEJ, in that small deletions and insertions can occur at the cleavage site. MMEJ can make use of homologous sequences of a few base pairs flanking the cleavage site to drive a favored end-joining DNA repair outcome. In some instances, it may be possible to predict likely repair outcomes based on analysis of potential microhomologies in the nuclease target regions.

[000237] Thus, in some cases, homologous recombination can be used to insert an exogenous polynucleotide sequence into the target nucleic acid cleavage site. An exogenous polynucleotide sequence is termed a donor polynucleotide (or donor or donor sequence or polynucleotide donor template) herein. The donor polynucleotide, a portion of the donor polynucleotide, a copy of the donor polynucleotide, or a portion of a copy of the donor polynucleotide can be inserted into the target nucleic acid cleavage site. The donor polynucleotide can be an exogenous polynucleotide sequence, i.e., a sequence that does not naturally occur at the target nucleic acid cleavage site.

[000238] The modifications of the target DNA due to NHEJ and/or HDR can lead to, for example, mutations, deletions, alterations, integrations, gene correction, gene replacement, gene tagging, transgene insertion, nucleotide deletion, gene disruption, translocations and/or gene mutation. The processes of deleting genomic DNA and integrating non-native nucleic acid into genomic DNA are examples of genome editing.

[000239] CRISPR Endonuclease System

[000240] A CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) genomic locus can be found in the genomes of many prokaryotes (e.g. , bacteria and archaea). In prokaryotes, the CRISPR locus encodes products that function as a type of immune system to help defend the prokaryotes against foreign invaders, such as virus and phage. There are three stages of CRISPR locus function: integration of new sequences into the CRISPR locus, expression of CRISPR RNA (crRNA), and silencing of foreign invader nucleic acid. Five types of CRISPR systems (e.g, Type I, Type II, Type III, Type U, and Type V) have been identified.

[000241] A CRISPR locus includes a number of short repeating sequences referred to as "repeats." When expressed, the repeats can form secondary structures (e.g., hairpins) and/or comprise unstructured single-stranded sequences. The repeats usually occur in clusters and frequently diverge between species. The repeats are regularly interspaced with unique intervening sequences referred to as "spacers," resulting in a repeat-spacer-repeat locus architecture. The spacers are identical to or have high homology with known foreign invader sequences. A spacer-repeat unit encodes a crisprRNA (crRNA), which is processed into a mature form of the spacer-repeat unit. A crRNA comprises a "seed" or spacer sequence that is involved in targeting a target nucleic acid (in the naturally occurring form in prokaryotes, the spacer sequence targets the foreign invader nucleic acid). A spacer sequence is located at the 5' or 3' end of the crRNA.

[000242] A CRISPR locus also comprises polynucleotide sequences encoding CRISPR Associated (Cas) genes. Cas genes encode endonucleases involved in the biogenesis and the interference stages of crRNA function in prokaryotes. Some Cas genes comprise homologous secondary and/or tertiary structures.

[000243] Type II CRISPR Systems

[000244] crRNA biogenesis in a Type II CRISPR system in nature requires a trans-activating CRISPR RNA (tracrRNA). The tracrRNA can be modified by endogenous RNaselll, and then hybridizes to a crRNA repeat in the pre-crRNA array. Endogenous RNaselll can be recruited to cleave the pre-crRNA. Cleaved crRNAs can be subjected to exoribonuclease trimming to produce the mature crRNA form (e.g., 5' trimming). The tracrRNA can remain hybridized to the crRNA, and the tracrRNA and the crRNA associate with a site-directed polypeptide (e.g., Cas9). The crRNA of the crRNA-tracrRNA-Cas9 complex can guide the complex to a target nucleic acid to which the crRNA can hybridize. Hybridization of the crRNA to the target nucleic acid can activate Cas9 for targeted nucleic acid cleavage. The target nucleic acid in a Type II CRISPR system is referred to as a protospacer adjacent motif (PAM). In nature, the PAM is essential to facilitate binding of a site-directed polypeptide (e.g., Cas9) to the target nucleic acid. Type II systems (also referred to as Nmeni or CASS4) are further subdivided into Type II-A (CASS4) and II-B (CASS4a). Jinek et al, Science, JJ 7(6096):816-821 (2012) showed that the CRISPR/Cas9 system is useful for RNA-programmable genome editing, and international patent application publication number WO2013/176772 provides numerous examples and applications of the CRISPR/Cas endonuclease system for site-specific gene editing.

[000245] Type V CRISPR Systems

[000246] Type V CRISPR systems have several important differences from Type II systems. For example, Cpfl is a single RNA-guided endonuclease that, in contrast to Type II systems, lacks tracrRNA. In fact, Cpfl -associated CRISPR arrays can be processed into mature crRNAs without the requirement of an additional trans-activating tracrRNA. The Type V CRISPR array can be processed into short mature crRNAs of 42-44 nucleotides in length, with each mature crRNA beginning with 19 nucleotides of direct repeat followed by 23-25 nucleotides of spacer sequence. In contrast, mature crRNAs in Type II systems can start with 20-24 nucleotides of spacer sequence followed by about 22 nucleotides of direct repeat. Also, Cpfl can utilize a T- rich protospacer-adjacent motif such that Cpfl -crRNA complexes efficiently cleave target DNA preceded by a short T-rich PAM, which is in contrast to the G-rich PAM following the target DNA for Type II systems. Thus, Type V systems cleave at a point that is distant from the PAM, while Type II systems cleave at a point that is adjacent to the PAM. In addition, in contrast to Type II systems, Cpfl cleaves DNA via a staggered DNA double-stranded break with a 4 or 5 nucleotide 5’ overhang. Type II systems cleave via a blunt double-stranded break. Similar to Type II systems, Cpfl contains a predicted RuvC-like endonuclease domain, but lacks a second HNH endonuclease domain, which is in contrast to Type II systems.

[000247] Cas Genes/Polypeptides and Protospacer Adjacent Motifs

[000248] Exemplary CRISPR/Cas polypeptides include the Cas9 polypeptides in Fig. 1 of Fonfara et al, Nucleic Acids Research, 42 2577-2590 (2014). The CRISPR/Cas gene naming system has undergone extensive rewriting since the Cas genes were discovered. Fig. 5 of Fonfara, supra, provides PAM sequences for the Cas9 polypeptides from various species. [000249] Site-Directed Polypeptides

[000250] A site-directed polypeptide is a nuclease used in genome editing to cleave DNA and/or induce site-directed mutagenesis. The site-directed nuclease can be administered to a cell or a patient as either: one or more polypeptides, or one or more mRNAs encoding the polypeptide. Any of the enzymes or orthologs listed in SEQ ID NOs. 1-612, or disclosed herein, can be utilized in the methods herein.

[000251] In the context of a CRISPR/Cas or CRISPR/Cpfl system, the site-directed polypeptide can bind to a guide RNA that, in turn, specifies the site in the target DNA to which the polypeptide is directed. In the CRISPR/Cas or CRISPR/Cpfl systems disclosed herein, the site-directed polypeptide can be an endonuclease, such as a DNA endonuclease.

[000252] A site-directed polypeptide can comprise a plurality of nucleic acid-cleaving (i.e.. nuclease) domains. Two or more nucleic acid-cleaving domains can be linked together via a linker. For example, the linker can comprise a flexible linker. Linkers can comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, 40 or more amino acids in length.

[000253] Naturally-occurring wild-type Cas9 enzymes comprise two nuclease domains, a HNH nuclease domain and a RuvC domain. Herein, the“Cas9” refers to both naturally occurring and recombinant Cas9s. Cas9 enzymes contemplated herein can comprise a HNH or HNH-like nuclease domain, and/or a RuvC or RuvC-like nuclease domain.

[000254] HNH or HNH-like domains comprise a McrA-like fold. HNH or HNH-like domains comprises two antiparallel b-strands and an a-helix. HNH or HNH-like domains comprises a metal binding site (e.g., a divalent cation binding site). HNH or HNH-like domains can cleave one strand of a target nucleic acid (e.g., the complementary strand of the crRNA targeted strand).

[000255] RuvC or RuvC-like domains comprise an RNaseH or RNaseH-like fold.

RuvC/RNaseH domains are involved in a diverse set of nucleic acid-based functions including acting on both RNA and DNA. The RNaseH domain comprises 5 b-strands surrounded by a plurality of a-helices. RuvC/RNaseH or RuvC/RNaseH-like domains comprise a metal binding site (e.g., a divalent cation binding site). RuvC/RNaseH or RuvC/RNaseH-like domains can cleave one strand of a target nucleic acid (e.g., the non-complementary strand of a double- stranded target DNA).

[000256] Site-directed polypeptides can introduce double-strand breaks or single-strand breaks in nucleic acids, e.g., genomic DNA. The double-strand break can stimulate a cell's endogenous DNA-repair pathways (e.g. , HDR or NHEJ or ANHEJ or MMEJ). NHEJ can repair cleaved target nucleic acid without the need for a homologous template. This can sometimes result in small deletions or insertions (indels) in the target nucleic acid at the site of cleavage, and can lead to disruption or alteration of gene expression. HDR can occur when a homologous repair template, or donor, is available. The homologous donor template can comprise sequences that are homologous to sequences flanking the target nucleic acid cleavage site. The sister chromatid can be used by the cell as the repair template. However, for the purposes of genome editing, the repair template can be supplied as an exogenous nucleic acid, such as a plasmid, duplex oligonucleotide, single-strand oligonucleotide or viral nucleic acid. With exogenous donor templates, an additional nucleic acid sequence (such as a transgene) or modification (such as a single or multiple base change or a deletion) can be introduced between the flanking regions of homology so that the additional or altered nucleic acid sequence also becomes incorporated into the target locus. MMEJ can result in a genetic outcome that is similar to NHEJ, in that small deletions and insertions can occur at the cleavage site. MMEJ can make use of homologous sequences of a few base pairs flanking the cleavage site to drive a favored end-joining DNA repair outcome. In some instances, it may be possible to predict likely repair outcomes based on analysis of potential microhomologies in the nuclease target regions.

[000257] Thus, in some cases, homologous recombination can be used to insert an exogenous polynucleotide sequence into the target nucleic acid cleavage site. An exogenous polynucleotide sequence is termed a donor polynucleotide (or donor or donor sequence) herein. The donor polynucleotide, a portion of the donor polynucleotide, a copy of the donor polynucleotide, or a portion of a copy of the donor polynucleotide can be inserted into the target nucleic acid cleavage site. The donor polynucleotide can be an exogenous polynucleotide sequence, i.e., a sequence that does not naturally occur at the target nucleic acid cleavage site.

[000258] The site-directed polypeptide can comprise an amino acid sequence having at least 10%, at least 15%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 99%, or 100% amino acid sequence identity to a wild-type exemplary site-directed polypeptide [e.g., Cas9 from S. pyogenes, US2014/0068797 Sequence ID No. 8 or Sapranauskas et al., Nucleic Acids Res, 39(21): 9275-9282 (2011)], and various other site-directed polypeptides. The site-directed polypeptide can comprise at least 70, 75, 80, 85, 90, 95, 97, 99, or 100% identity to a wild-type site-directed polypeptide (e.g., Cas9 from S. pyogenes, supra) over 10 contiguous amino acids. The site-directed polypeptide can comprise at most: 70, 75, 80, 85, 90, 95, 97, 99, or 100% identity to a wild-type site-directed polypeptide (e.g, Cas9 from S. pyogenes, supra) over 10 contiguous amino acids. The site-directed polypeptide can comprise at least: 70, 75, 80, 85, 90, 95, 97, 99, or 100% identity to a wild-type site-directed polypeptide (e.g., Cas9 from .S' pyogenes, supra) over 10 contiguous amino acids in a HNH nuclease domain of the site-directed polypeptide. The site-directed polypeptide can comprise at most: 70, 75, 80, 85, 90, 95, 97, 99, or 100% identity to a wild-type site-directed polypeptide (e.g., Cas9 from .S' pyogenes, supra) over 10 contiguous amino acids in a HNH nuclease domain of the site-directed polypeptide. The site-directed polypeptide can comprise at least: 70, 75, 80, 85, 90, 95, 97, 99, or 100% identity to a wild-type site-directed polypeptide (e.g., Cas9 from S. pyogenes, supra) over 10 contiguous amino acids in a RuvC nuclease domain of the site-directed polypeptide. The site-directed polypeptide can comprise at most: 70, 75, 80, 85, 90, 95, 97, 99, or 100% identity to a wild-type site-directed polypeptide (e.g., Cas9 from S. pyogenes, supra) over 10 contiguous amino acids in a RuvC nuclease domain of the site-directed polypeptide.

[000259] The site-directed polypeptide can comprise a modified form of a wild-type exemplary site-directed polypeptide. The modified form of the wild- type exemplary site-directed polypeptide can comprise a mutation that reduces the nucleic acid-cleaving activity of the site- directed polypeptide. The modified form of the wild-type exemplary site-directed polypeptide can have less than 90%, less than 80%, less than 70%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, less than 5%, or less than 1% of the nucleic acid-cleaving activity of the wild-type exemplary site-directed polypeptide (e.g., Cas9 from S. pyogenes, supra). The modified form of the site-directed polypeptide can have no substantial nucleic acid-cleaving activity. When a site-directed polypeptide is a modified form that has no substantial nucleic acid-cleaving activity, it is referred to herein as "enzymatically inactive."

[000260] The modified form of the site-directed polypeptide can comprise a mutation such that it can induce a SSB on a target nucleic acid (e.g., by cutting only one of the sugar-phosphate backbones of a double-strand target nucleic acid). The mutation can result in less than 90%, less than 80%, less than 70%, less than 60%, less than 50%, less than 40%, less than 30%, less than 20%, less than 10%, less than 5%, or less than 1% of the nucleic acid-cleaving activity in one or more of the plurality of nucleic acid-cleaving domains of the wild-type site directed polypeptide (e.g, Cas9 from S. pyogenes, supra). The mutation can result in one or more of the plurality of nucleic acid-cleaving domains retaining the ability to cleave the complementary strand of the target nucleic acid, but reducing its ability to cleave the non-complementary strand of the target nucleic acid. The mutation can result in one or more of the plurality of nucleic acid-cleaving domains retaining the ability to cleave the non-complementary strand of the target nucleic acid, but reducing its ability to cleave the complementary strand of the target nucleic acid. For example, residues in the wild-type exemplary S. pyogenes Cas9 polypeptide, such as Asp 10, His840, Asn854 and Asn856, are mutated to inactivate one or more of the plurality of nucleic acid-cleaving domains (e.g., nuclease domains). The residues to be mutated can correspond to residues AsplO, His840, Asn854 and Asn856 in the wild-type exemplary S. pyogenes Cas9 polypeptide (e.g., as determined by sequence and/or structural alignment). Non-limiting examples of mutations include D10A, H840A, N854A or N856A. Mutations other than alanine substitutions can be suitable.

[000261] A D10A mutation can be combined with one or more of H840A, N854A, or N856A mutations to produce a site-directed polypeptide substantially lacking DNA cleavage activity. A H840A mutation can be combined with one or more of D10A, N854A, or N856A mutations to produce a site-directed polypeptide substantially lacking DNA cleavage activity. A N854A mutation can be combined with one or more of H840A, D10A, or N856A mutations to produce a site-directed polypeptide substantially lacking DNA cleavage activity. A N856A mutation can be combined with one or more of H840A, N854A, or D10A mutations to produce a site-directed polypeptide substantially lacking DNA cleavage activity. Site-directed polypeptides that comprise one substantially inactive nuclease domain are referred to as“nickases”.

[000262] Nickase variants of RNA-guided endonucleases, for example Cas9, can be used to increase the specificity of CRISPR-mediated genome editing. Wild type Cas9 is typically guided by a single guide RNA designed to hybridize with a specified ~20 nucleotide sequence in the target sequence (such as an endogenous genomic locus). However, several mismatches can be tolerated between the guide RNA and the target locus, effectively reducing the length of required homology in the target site to, for example, as little as 13 nt of homology, and thereby resulting in elevated potential for binding and double-strand nucleic acid cleavage by the CRISPR/Cas9 complex elsewhere in the target genome - also known as off-target cleavage. Because nickase variants of Cas9 each only cut one strand, in order to create a double-strand break it is necessary for a pair of nickases to bind in close proximity and on opposite strands of the target nucleic acid, thereby creating a pair of nicks, which is the equivalent of a double-strand break. This requires that two separate guide RNAs - one for each nickase - must bind in close proximity and on opposite strands of the target nucleic acid. This requirement essentially doubles the minimum length of homology needed for the double-strand break to occur, thereby reducing the likelihood that a double-strand cleavage event will occur elsewhere in the genome, where the two guide RNA sites - if they exist - are unlikely to be sufficiently close to each other to enable the double- strand break to form. As described in the art, nickases can also be used to promote HDR versus NHEJ. HDR can be used to introduce selected changes into target sites in the genome through the use of specific donor sequences that effectively mediate the desired changes.

[000263] Mutations contemplated can include substitutions, additions, and deletions, or any combination thereof. The mutation converts the mutated amino acid to alanine. The mutation converts the mutated amino acid to another amino acid (e.g., glycine, serine, threonine, cysteine, valine, leucine, isoleucine, methionine, proline, phenylalanine, tyrosine, tryptophan, aspartic acid, glutamic acid, asparagines, glutamine, histidine, lysine, or arginine). The mutation converts the mutated amino acid to a non-natural amino acid (e.g., selenomethionine). The mutation converts the mutated amino acid to amino acid mimics (e.g., phosphomimics). The mutation can be a conservative mutation. For example, the mutation converts the mutated amino acid to amino acids that resemble the size, shape, charge, polarity, conformation, and/or retainers of the mutated amino acids (e.g., cysteine/serine mutation, lysine/asparagine mutation, histidine/phenylalanine mutation). The mutation can cause a shift in reading frame and/or the creation of a premature stop codon. Mutations can cause changes to regulatory regions of genes or loci that affect expression of one or more genes.

[000264] The site-directed polypeptide (e.g., variant, mutated, enzymatically inactive and/or conditionally enzymatically inactive site-directed polypeptide) can target nucleic acid. The site- directed polypeptide (e.g., variant, mutated, enzymatically inactive and/or conditionally enzymatically inactive endoribonuclease) can target DNA. The site-directed polypeptide (e.g., variant, mutated, enzymatically inactive and/or conditionally enzymatically inactive

endoribonuclease) can target RNA.

[000265] The site-directed polypeptide can comprise one or more non-native sequences (e.g, the site-directed polypeptide is a fusion protein).

[000266] The site-directed polypeptide can comprise an amino acid sequence comprising at least 15% amino acid identity to a Cas9 from a bacterium (e.g. , S. pyogenes), a nucleic acid binding domain, and two nucleic acid cleaving domains (/. e. , a HNH domain and a RuvC domain).

[000267] The site-directed polypeptide can comprise an amino acid sequence comprising at least 15% amino acid identity to a Cas9 from a bacterium (e.g. , S. pyogenes), and two nucleic acid cleaving domains (i.e., a HNH domain and a RuvC domain).

[000268] The site-directed polypeptide can comprise an amino acid sequence comprising at least 15% amino acid identity to a Cas9 from a bacterium (e.g. , S. pyogenes), and two nucleic acid cleaving domains, wherein one or both of the nucleic acid cleaving domains comprise at least 50% amino acid identity to a nuclease domain from Cas9 from a bacterium (e.g. , S.

pyogenes).

[000269] The site-directed polypeptide can comprise an amino acid sequence comprising at least 15% amino acid identity to a Cas9 from a bacterium (e.g. , S. pyogenes), two nucleic acid cleaving domains (/. e. , a HNH domain and a RuvC domain), and non-native sequence (for example, a nuclear localization signal) or a linker linking the site-directed polypeptide to a non native sequence.

[000270] The site-directed polypeptide can comprise an amino acid sequence comprising at least 15% amino acid identity to a Cas9 from a bacterium (e.g. , S. pyogenes), two nucleic acid cleaving domains (i.e., a HNH domain and a RuvC domain), wherein the site-directed polypeptide comprises a mutation in one or both of the nucleic acid cleaving domains that reduces the cleaving activity of the nuclease domains by at least 50%.

[000271] The site-directed polypeptide can comprise an amino acid sequence comprising at least 15% amino acid identity to a Cas9 from a bacterium (e.g. , S. pyogenes), and two nucleic acid cleaving domains (i.e., a HNH domain and a RuvC domain), wherein one of the nuclease domains comprises mutation of aspartic acid 10, and/or wherein one of the nuclease domains can comprise a mutation of histidine 840, and wherein the mutation reduces the cleaving activity of the nuclease domain(s) by at least 50%.

[000272] The one or more site-directed polypeptides, e.g. DNA endonucleases, can comprise two nickases that together effect one double-strand break at a specific locus in the genome, or four nickases that together effect or cause two double -strand breaks at specific loci in the genome. Alternatively, one site-directed polypeptide, e.g. DNA endonuclease, can effect or cause one double-strand break at a specific locus in the genome.

[000273] Non-limiting examples of Cas9 orthologs from other bacterial strains including but not limited to, Cas proteins identified in Acaryochloris marina MBIC11017; Acetohalobium arabaticum DSM 5501; Acidithiobacillus caldus, Acidithiobacillus ferrooxidans ATCC 23270; Alicyclobacillus acidocaldarius LAA1; Alicyclobacillus acidocaldarius subsp. acidocaldarius DSM 446; Allochromatium vinosum DSM 180; Ammonifex degensii KC4; Anabaena variabilis ATCC 29413; Arthrospira maxima CS-328; Arthrospira platensis str. Paraca; Arthrospira sp. PCC 8005; Bacillus pseudomycoides DSM 12442; Bacillus selenitireducens MLS 10;

Burkholderiales bacterium 1 _ 1 _ 47; Caldicelulosiruptor becscii DSM 6725; Candidatus

Desulforudis audaxviator MP104C; Caldicellulosiruptor hydrothermalis_\0&; Clostridium phage c-st; Clostridium botulinum A3 str. LochMaree; Clostridium botulinum Ba4 str. 657; Clostridium difficile QCD-63q42; Crocosphaera watsonii WH 8501; Cyanothece sp. ATCC 51142; Cyanothece sp. CCY0110; Cyanothece sp. PCC 7424; Cyanothece sp. PCC 7822;

Exiguobacterium sibiricum 255-15; Finegoldia magna ATCC 29328; Ktedonobacter racemifer DSM 44963; Lactobacillus delbrueckii subsp. bulgaricus PB2003/044-T3-4; Lactobacillus salivarius ATCC 11741; Listeria innocua; Lyngbya sp. PCC 8106; Marinobacter sp. ELB17; Methanohalobium evestigatum Z-7303; Microcystis phage Ma-LMMO 1 : Microcystis aeruginosa N I ES-843 : Microscilla marina ATCC 23134; Microcoleus chthonoplastes PCC 7420; Neisseria meningitidis ; Nitrosococcus halophilus Nc4; Nocardiopsis dassonvillei subsp. dassonvillei DSM 43111; Nodularia spumigena CCY9414; Nostoc sp. PCC 7120; Oscillatoria sp. PCC 6506; Pelotomaculum thermopropionicumJSV; Petrotoga mobilis SJ95; Polaromonas

naphthalenivorans CJ2; Polaromonas sp. JS666; Pseudoalteromonas haloplanktis TAC125; Streptomyces pristinaespiralis ATCC 25486; Streptomyces pristinaespiralis ATCC 25486; Streptococcus thermophilus ; Streptomyces viridochromogenes DSM 40736; Streptosporangium roseum DSM 43021; Synechococcus sp. PCC 7335; and Thermosipho africanus TCF52B (Chylinski et al., RNA Biol., 2013; 10(5): 726-737.

[000274] In addition to Cas9 orthologs, other Cas9 variants such as fusion proteins of inactive dCas9 and effector domains with different functions can be served as a platform for genetic modulation. Any of the foregoing enzymes can be useful in the present disclosure.

[000275] Further examples of endonucleases that can be utilized in the present disclosure are provided in SEQ ID NOs: 1-612. These proteins can be modified before use or can be encoded in a nucleic acid sequence such as a DNA, RNA or mRNA or within a vector construct such as the plasmids or adeno-associated virus (AAV) vectors taught herein. Further, they can be codon optimized.

[000276] Genome-targeting Nucleic Acid

[000277] The present disclosure provides a genome -targeting nucleic acid that can direct the activities of an associated polypeptide (e.g., a site-directed polypeptide) to a specific target sequence within a target nucleic acid. The genome-targeting nucleic acid can be an RNA. A genome-targeting RNA is referred to as a“guide RNA” or“gRNA” herein. A guide RNA can comprise at least a spacer sequence that hybridizes to a target nucleic acid sequence of interest, and a CRISPR repeat sequence. In Type II systems, the gRNA also comprises a second RNA called the tracrRNA sequence. In the Type II gRNA, the CRISPR repeat sequence and tracrRNA sequence hybridize to each other to form a duplex. In the Type V gRNA, the crRNA forms a duplex. In both systems, the duplex can bind a site-directed polypeptide, such that the guide RNA and site-direct polypeptide form a complex. The genome-targeting nucleic acid can provide target specificity to the complex by virtue of its association with the site-directed polypeptide. The genome-targeting nucleic acid thus can direct the activity of the site-directed polypeptide.

[000278] Exemplary guide RNAs include the spacer sequences in SEQ ID NOs: 5272-5313, 5398-5409, and 5434-5443 of the Sequence Listing, shown with genome location of their target sequence (See SEQ ID NOs: 5314-5355 in Figure 2B; 5410-5421 in Figure 2E; and 5444-5453 in Figure 2E) and the associated Cas9 cut site, wherein the genome location is based on the GRCh38/hg38 human genome assembly.

[000279] Each guide RNA can be designed to include a spacer sequence complementary to its genomic target sequence. For example, each of the spacer sequences in SEQ ID NOs: 5272- 5313, 5398-5409, and 5434-5443 of the Sequence Listing can be put into a single RNA chimera or a crRNA (along with a corresponding tracrRNA). See Jinek et al., Science, 337, 816-821 (2012) and Deltcheva et al., Nature, 471, 602-607 (2011).

[000280] The genome -targeting nucleic acid can be a double-molecule guide RNA. The genome-targeting nucleic acid can be a single-molecule guide RNA. The double-molecule guide RNA or single-molecule guide RNA can be modified.

[000281] A double-molecule guide RNA can comprise two strands of RNA. The first strand comprises in the 5' to 3' direction, an optional spacer extension sequence, a spacer sequence and a minimum CRISPR repeat sequence. The second strand can comprise a minimum tracrRNA sequence (complementary to the minimum CRISPR repeat sequence), a 3’ tracrRNA sequence and an optional tracrRNA extension sequence.

[000282] A single-molecule guide RNA (sgRNA) in a Type II system can comprise, in the 5' to 3' direction, an optional spacer extension sequence, a spacer sequence, a minimum CRISPR repeat sequence, a single-molecule guide linker, a minimum tracrRNA sequence, a 3’ tracrRNA sequence and an optional tracrRNA extension sequence. The optional tracrRNA extension can comprise elements that contribute additional functionality (e.g., stability) to the guide RNA. The single -molecule guide linker can link the minimum CRISPR repeat and the minimum tracrRNA sequence to form a hairpin structure. The optional tracrRNA extension can comprise one or more hairpins. [000283] The sgRNA can comprise a variable length spacer sequence with 17-30 nucleotides at the 5’ end of the sgRNA sequence (Table 4). In other examples, the sgRNA can comprise a variable length spacer sequence with 17-24 nucleotides at the 5’ end of the sgRNA sequence.

[000284] The sgRNA can comprise a 20 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a less than 20 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 19 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 18 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 17 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a more than 20 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 21 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 22 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 23 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 24 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 25 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 26 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 27 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 28 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 29 nucleotide spacer sequence at the 5’ end of the sgRNA sequence. The sgRNA can comprise a 30 nucleotide spacer sequence at the 5’ end of the sgRNA sequence.

[000285] The sgRNA can comprise no uracil at the 3’end of the sgRNA sequence, such as in SEQ ID NOs: 5268, 5495, 5498, 5501, and 5504 of Table 4. The sgRNA can comprise one or more uracil at the 3’end of the sgRNA sequence, such as in SEQ ID NO: 5269, 5267, 5494,

5496, 5497, 5499, 5500, 5502, 5503, and 5505 in Table 4. For example, the sgRNA can comprise 1 uracil (U) at the 3’ end of the sgRNA sequence. The sgRNA can comprise 2 uracil (UU) at the 3’ end of the sgRNA sequence. The sgRNA can comprise 3 uracil (UUU) at the 3’ end of the sgRNA sequence. The sgRNA can comprise 4 uracil (UUUU) at the 3’ end of the sgRNA sequence. The sgRNA can comprise 5 uracil (UUUUU) at the 3’ end of the sgRNA sequence. The sgRNA can comprise 6 uracil (UUUUUU) at the 3’ end of the sgRNA sequence. The sgRNA can comprise 7 uracil (UUUUUUU) at the 3’ end of the sgRNA sequence. The sgRNA can comprise 8 uracil (UUUUUUUU) at the 3’ end of the sgRNA sequence.

[000286] The sgRNA can be unmodified or modified. For example, modified sgRNAs can comprise one or more 2'-0-methyl phosphorothioate nucleotides. Table 4

[000287] A single-molecule guide RNA (sgRNA) in a Type V system can comprise, in the 5' to 3' direction, a minimum CRISPR repeat sequence and a spacer sequence.

[000288] By way of illustration, guide RNAs used in the CRISPR/Cas/Cpfl system, or other smaller RNAs, can be readily synthesized by chemical means, as illustrated below and described in the art. While chemical synthetic procedures are continually expanding, purifications of such RNAs by procedures such as high performance liquid chromatography (HPLC, which avoids the use of gels such as PAGE) tends to become more challenging as polynucleotide lengths increase significantly beyond a hundred or so nucleotides. One approach used for generating RNAs of greater length is to produce two or more molecules that are ligated together. Much longer RNAs, such as those encoding a Cas9 or Cpfl endonuclease, are more readily generated enzymatically. Various types of RNA modifications can be introduced during or after chemical synthesis and/or enzymatic generation of RNAs, e.g., modifications that enhance stability, reduce the likelihood or degree of innate immune response, and/or enhance other attributes, as described in the art.

[000289] gRNAs or sgRNAs that target the R838H mutation in a GUCY2D gene

[000290] The present disclosure provides one or more gRNAs (or sgRNAs) for editing a R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD (Figures 2 A and 2D).

[000291] The one or more gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5293 of the Sequence Listing. These gRNA sequences have zero mismatches with the R838H GUCY2D allele and 1 mismatch with the wild-type GUCY2D allele.

[000292] The one or more gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398-5409 of the Sequence Listing. These gRNA sequences have 1 mismatch with the R838H GUCY2D allele and 2 mismatches with the wild-type GUCY2D allele.

[000293] gRNAs or sgRNAs disclosed herein can associate with a DNA endonuclease to form a ribonucleoprotein complex, which stably edits the R838H mutation in a GUCY2D gene. This editing is not transient.

[000294] gRNAs or sgRNAs that target the R838C mutation in a GUCY2D gene

[000295] The present disclosure provides one or more gRNAs (or sgRNAs) for editing a R838C mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD (Figures 2 A and 2D). [000296] The one or more gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5294-5303 of the Sequence Listing. These gRNA sequences have zero mismatches with the R838C GUCY2D allele and 1 mismatch with the wild-type GUCY2D allele.

[000297] The one or more gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in 5398-5409 of the Sequence Listing. These gRNA sequences have 1 mismatch with the R838C GUCY2D allele and 2 mismatches with the wild- type GUCY2D allele.

[000298] gRNAs or sgRNAs disclosed herein can associate with a DNA endonuclease to form a ribonucleoprotein complex, which stably edits the R838C mutation in a GUCY2D gene. This editing is not transient.

[000299] gRNAs or sgRNAs that target the R838S mutation in a GUCY2D gene

[000300] The present disclosure provides one or more gRNAs (or sgRNAs) for editing a R838S mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD (figures 2 A and 2D).

[000301] The one or more gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5304-5313 of the Sequence Listing. These gRNA sequences have zero mismatches with the R838S GUCY2D allele and 1 mismatch with the wild-type GUCY2D allele.

[000302] The one or more gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in 5434-5443 of the Sequence Listing. These gRNA sequences have 1 mismatch with the R838S GUCY2D allele and 2 mismatches with the wild- type GUCY2D allele.

[000303] gRNAs or sgRNAs disclosed herein can associate with a DNA endonuclease to form a ribonucleoprotein complex, which stably edits the R838S mutation in a GUCY2D gene. This editing is not transient.

[000304] “Double mutation” guide RNAs

[000305] The present disclosure provides gRNAs (or sgRNAs), referred to herein as,“double mutation” guide RNAs, that can edit multiple mutant alleles of the GUCY2D gene.

[000306] In certain examples, the double mutation guide RNAs can comprise a spacer sequence comprising 1 mismatched base with, for example, an R838C mutant allele and comprising a second mismatched base with, for example, a R838H mutant allele. Double mutation gRNAs that target the R838C and R838H mutant alleles are referred to herein as “R838CH double mutation” gRNAs.

[000307] In certain other examples, the double mutation guide RNAs can comprise a spacer sequence comprising 1 mismatched base with, for example, an R838S mutant allele and comprising a second mismatched based with, for example a R838H mutant allele. Double mutation gRNAs that target the R838S and R838H mutant alleles are referred to herein as “R838SH double mutation” gRNAs.

[000308] The double mutation guide RNAs (e.g., R838CH double mutation gRNAs or R838SH double mutation gRNAs) can comprise 2 mismatched bases with a wild-type allele. The double mutation guide RNAs can comprise reduced off-target editing of a wild-type GUCY2D allele.

[000309] gRNAs or sgRNAs that target the R838C and R838H mutations in a GUCY2D gene (R838CH double mutation gRNAs)

[000310] The present disclosure provides gRNAs (or sgRNAs) for editing a R838C or R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD (Figure 2D).

[000311] The gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398-5409 of the Sequence Listing. These gRNA sequences have 1 mismatch with the R838C GUCY2D allele and R838H GUCY2D allele.

These gRNA sequences have 2 mismatches with the wild-type GUCY2D allele.

[000312] These gRNAs can be used to treat patients with a R838H mutation in the GUCY2D gene or patients with an R838C mutation in the GUCY2D gene. These gRNAs can be specific for both the R838H and R838C mutant allele because they have two consecutive mismatches compared to a sequence that corresponds with the wild-type codon 838. The two consecutive mismatches in the gRNA sequence reduce the probability that the wild-type GUCY2D sequence will be cleaved because the two mismatches within the gRNA are consecutive and not separated (Figure 3 of Klein et al“Hybridization Kinetics Explains CRISPR-Cas Off-Targeting Rules”,

Cell Reports 22, February 2018, pages 1413-1423).

[000313] gRNAs or sgRNAs disclosed herein can associate with a DNA endonuclease to form a ribonucleoprotein complex, which stably edits either the R838C mutation or R838H mutation in a GUCY2D gene. This editing is not transient. [000314] gRNAs or sgRNAs that target the R838S and R838H mutations in a GUCY2D gene (R838SH double mutation gRNAs)

[000315] The present disclosure provides gRNAs (or sgRNAs) for editing a R838S or R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD (Figure 2D).

[000316] The gRNAs can comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5434-5443 of the Sequence Listing. These gRNA sequences have 1 mismatch with the R838S GUCY2D allele and R838H GUCY2D allele. These gRNA sequences have 2 mismatches with the wild-type GUCY2D allele.

[000317] These gRNAs can be used to treat patients with a R838S mutation in the GUCY2D gene or patients with an R838H mutation in the GUCY2D gene. These gRNAs can be specific for both the R838S and R838H mutant allele because they have two consecutive mismatches compared to a sequence that corresponds with the wild-type codon 838. As described above, the two consecutive mismatches reduce the probability that the wild-type GUCY2D sequence will be cleaved because the two mismatches within the gRNA are consecutive and not separated.

[000318] gRNAs or sgRNAs disclosed herein can associate with a DNA endonuclease to form a ribonucleoprotein complex, which stably edits either the R838S mutation or R838H mutation in a GUCY2D gene. This editing is not transient.

[000319] Spacer Extension Sequence

[000320] In some examples of genome-targeting nucleic acids, a spacer extension sequence can modify activity, provide stability and/or provide a location for modifications of a genome targeting nucleic acid. A spacer extension sequence can modify on- or off-target activity or specificity. In some examples, a spacer extension sequence can be provided. The spacer extension sequence can have a length of more than 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 1000, 2000, 3000, 4000, 5000, 6000, or 7000 or more nucleotides. The spacer extension sequence can have a length of less than 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 1000, 2000, 3000, 4000, 5000, 6000, 7000 or more nucleotides. The spacer extension sequence can be less than 10 nucleotides in length. The spacer extension sequence can be between 10-30 nucleotides in length. The spacer extension sequence can be between 30-70 nucleotides in length.

[000321] The spacer extension sequence can comprise another moiety ( e.g ., a stability control sequence, an endoribonuclease binding sequence, a ribozyme). The moiety can decrease or increase the stability of a nucleic acid targeting nucleic acid. The moiety can be a transcriptional terminator segment (i.e., a transcription termination sequence). The moiety can function in a eukaryotic cell. The moiety can function in a prokaryotic cell. The moiety can function in both eukaryotic and prokaryotic cells. Non-limiting examples of suitable moieties include: a 5' cap (e.g., a 7-methylguanylate cap (m7 G)), a riboswitch sequence (e.g., to allow for regulated stability and/or regulated accessibility by proteins and protein complexes), a sequence that forms a dsRNA duplex (i.e.. a hairpin), a sequence that targets the RNA to a subcellular location (e.g., nucleus, mitochondria, chloroplasts, and the like), a modification or sequence that provides for tracking (e.g., direct conjugation to a fluorescent molecule, conjugation to a moiety that facilitates fluorescent detection, a sequence that allows for fluorescent detection, etc.), and/or a modification or sequence that provides a binding site for proteins (e.g., proteins that act on DNA, including transcriptional activators, transcriptional repressors, DNA methyltransferases, DNA demethylases, histone acetyltransferases, histone deacetylases, and the like).

[000322] Spacer Sequence

[000323] The spacer sequence hybridizes to a sequence in a target nucleic acid of interest. The spacer of a genome-targeting nucleic acid can interact with a target nucleic acid in a sequence- specific manner via hybridization (i.e., base pairing). The nucleotide sequence of the spacer can vary depending on the sequence of the target nucleic acid of interest. In a CRISPR/Cas system herein, the spacer sequence can be designed to hybridize to a target nucleic acid that is located 5' of a PAM of the Cas9 or Cpfl enzyme used in the system. The spacer can perfectly match the target sequence or can have mismatches. Each Cas9 enzyme has a particular PAM sequence that it recognizes in a target DNA. For example, S. pyogenes recognizes in a target nucleic acid a PAM that comprises the sequence 5'-NRG-3', where R comprises either A or G, where N is any nucleotide and N is immediately 3' of the target nucleic acid sequence targeted by the spacer sequence. For example, S. aureus Cas9 recognizes in a target nucleic acid a PAM that comprises the sequence 5'-NNGRRT-3', where R comprises either A or G, where N is any nucleotide and N is immediately 3' of the target nucleic acid sequence targeted by the spacer sequence. In certain examples, S. aureus Cas9 recognizes in a target nucleic acid a PAM that comprises the sequence 5'-NNGRRN-3', where R comprises either A or G, where N is any nucleotide and the N is immediately 3' of the target nucleic acid sequence targeted by the spacer sequence. For example, C. jejuni recognizes in a target nucleic acid a PAM that comprises the sequence 5'-NNNNACA- 3' or 5'-NNNNACAC-3', where N is any nucleotide and N is immediately 3' of the target nucleic acid sequence targeted by the spacer sequence. In certain examples, C. jejuni Cas9 recognizes in a target nucleic acid a PAM that comprises the sequence 5'-NNNVRYM-3' or 5’-NNVRYAC-3’, where V comprises either A, G or C, where R comprises either A or G, where Y comprises either C or T, where M comprises A or C, where N is any nucleotide and the N is immediately 3' of the target nucleic acid sequence targeted by the spacer sequence.

[000324] The target nucleic acid sequence can comprise 20 nucleotides. The target nucleic acid can comprise less than 20 nucleotides. The target nucleic acid can comprise more than 20 nucleotides. The target nucleic acid can comprise at least: 5, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30 or more nucleotides. The target nucleic acid can comprise at most: 5, 10, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30 or more nucleotides. The target nucleic acid sequence can comprise 20 bases immediately 5' of the first nucleotide of the PAM. For example, in a sequence comprising 5 ' -NNTSrNTSrNTSrNNNNNNTSrNTSrNTSrNTSrNRG- 3 ' (SEQ ID NO. 5270), the target nucleic acid can comprise the sequence that corresponds to the Ns, wherein N is any nucleotide, and the underlined NRG sequence is the S. pyogenes PAM.

[000325] The spacer sequence that hybridizes to the target nucleic acid can have a length of at least about 6 nucleotides (nt). The spacer sequence can be at least about 6 nt, at least about 10 nt, at least about 15 nt, at least about 18 nt, at least about 19 nt, at least about 20 nt, at least about 25 nt, at least about 30 nt, at least about 35 nt or at least about 40 nt, from about 6 nt to about 80 nt, from about 6 nt to about 50 nt, from about 6 nt to about 45 nt, from about 6 nt to about 40 nt, from about 6 nt to about 35 nt, from about 6 nt to about 30 nt, from about 6 nt to about 25 nt, from about 6 nt to about 20 nt, from about 6 nt to about 19 nt, from about 10 nt to about 50 nt, from about 10 nt to about 45 nt, from about 10 nt to about 40 nt, from about 10 nt to about 35 nt, from about 10 nt to about 30 nt, from about 10 nt to about 25 nt, from about 10 nt to about 20 nt, from about 10 nt to about 19 nt, from about 19 nt to about 25 nt, from about 19 nt to about 30 nt, from about 19 nt to about 35 nt, from about 19 nt to about 40 nt, from about 19 nt to about 45 nt, from about 19 nt to about 50 nt, from about 19 nt to about 60 nt, from about 20 nt to about 25 nt, from about 20 nt to about 30 nt, from about 20 nt to about 35 nt, from about 20 nt to about 40 nt, from about 20 nt to about 45 nt, from about 20 nt to about 50 nt, or from about 20 nt to about 60 nt. In some examples, the spacer can comprise 24 nucleotides. In some examples, the spacer can comprise 23 nucleotides. In some examples, the spacer can comprise 22 nucleotides. In some examples, the spacer can comprise 21 nucleotides. In some examples, the spacer sequence can comprise 20 nucleotides. In some examples, the spacer can comprise 19 nucleotides. In some examples, the spacer can comprise 18 nucleotides. In some examples, the spacer can comprise 17 nucleotides. [000326] In some examples, the percent complementarity between the spacer sequence and the target nucleic acid is at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97%, at least about 98%, at least about 99%, or 100%. In some examples, the percent complementarity between the spacer sequence and the target nucleic acid is at most about 30%, at most about 40%, at most about 50%, at most about 60%, at most about 65%, at most about 70%, at most about 75%, at most about 80%, at most about 85%, at most about 90%, at most about 95%, at most about 97%, at most about 98%, at most about 99%, or 100%. In some examples, the percent complementarity between the spacer sequence and the target nucleic acid is 100% over the six contiguous 5 '-most nucleotides of the target sequence of the complementary strand of the target nucleic acid. The percent complementarity between the spacer sequence and the target nucleic acid can be at least 60% over about 20 contiguous nucleotides. The length of the spacer sequence and the target nucleic acid can differ by 1 to 6 nucleotides, which can be thought of as a bulge or bulges.

[000327] The spacer sequence can be designed or chosen using a computer program. The computer program can use variables, such as predicted melting temperature, secondary structure formation, predicted annealing temperature, sequence identity, genomic context, chromatin accessibility, % GC, frequency of genomic occurrence (e.g., of sequences that are identical or are similar but vary in one or more spots as a result of mismatch, insertion or deletion), methylation status, presence of SNPs, and the like.

[000328] Minimum CRISPR Repeat Sequence

[000329] A minimum CRISPR repeat sequence can be a sequence with at least about 30%, about 40%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or 100% sequence identity to a reference CRISPR repeat sequence (e.g. , crRNA from S. pyogenes).

[000330] A minimum CRISPR repeat sequence can comprise nucleotides that can hybridize to a minimum tracrRNA sequence in a cell. The minimum CRISPR repeat sequence and a minimum tracrRNA sequence can form a duplex, i.e. a base-paired double-stranded structure. Together, the minimum CRISPR repeat sequence and the minimum tracrRNA sequence can bind to the site-directed polypeptide. At least a part of the minimum CRISPR repeat sequence can hybridize to the minimum tracrRNA sequence. At least a part of the minimum CRISPR repeat sequence can comprise at least about 30%, about 40%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or 100% complementary to the minimum tracrRNA sequence. At least a part of the minimum CRISPR repeat sequence can comprise at most about 30%, about 40%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or 100% complementary to the minimum tracrRNA sequence.

[000331] The minimum CRISPR repeat sequence can have a length from about 7 nucleotides to about 100 nucleotides. For example, the length of the minimum CRISPR repeat sequence is from about 7 nucleotides (nt) to about 50 nt, from about 7 nt to about 40 nt, from about 7 nt to about 30 nt, from about 7 nt to about 25 nt, from about 7 nt to about 20 nt, from about 7 nt to about 15 nt, from about 8 nt to about 40 nt, from about 8 nt to about 30 nt, from about 8 nt to about 25 nt, from about 8 nt to about 20 nt, from about 8 nt to about 15 nt, from about 15 nt to about 100 nt, from about 15 nt to about 80 nt, from about 15 nt to about 50 nt, from about 15 nt to about 40 nt, from about 15 nt to about 30 nt, or from about 15 nt to about 25 nt. In some examples, the minimum CRISPR repeat sequence can be approximately 9 nucleotides in length. The minimum CRISPR repeat sequence can be approximately 12 nucleotides in length.

[000332] The minimum CRISPR repeat sequence can be at least about 60% identical to a reference minimum CRISPR repeat sequence (e.g., wild-type crRNA from S. pyogenes) over a stretch of at least 6, 7, or 8 contiguous nucleotides. For example, the minimum CRISPR repeat sequence can be at least about 65% identical, at least about 70% identical, at least about 75% identical, at least about 80% identical, at least about 85% identical, at least about 90% identical, at least about 95% identical, at least about 98% identical, at least about 99% identical or 100% identical to a reference minimum CRISPR repeat sequence over a stretch of at least 6, 7, or 8 contiguous nucleotides.

[000333] Minimum tracrRNA Sequence

[000334] A minimum tracrRNA sequence can be a sequence with at least about 30%, about 40%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or 100% sequence identity to a reference tracrRNA sequence (e.g., wild type tracrRNA from S. pyogenes).

[000335] A minimum tracrRNA sequence can comprise nucleotides that hybridize to a minimum CRISPR repeat sequence in a cell. A minimum tracrRNA sequence and a minimum CRISPR repeat sequence form a duplex, i.e. a base-paired double -stranded structure. Together, the minimum tracrRNA sequence and the minimum CRISPR repeat can bind to a site-directed polypeptide. At least a part of the minimum tracrRNA sequence can hybridize to the minimum CRISPR repeat sequence. The minimum tracrRNA sequence can be at least about 30%, about 40%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or 100% complementary to the minimum CRISPR repeat sequence.

[000336] The minimum tracrRNA sequence can have a length from about 7 nucleotides to about 100 nucleotides. For example, the minimum tracrRNA sequence can be from about 7 nucleotides (nt) to about 50 nt, from about 7 nt to about 40 nt, from about 7 nt to about 30 nt, from about 7 nt to about 25 nt, from about 7 nt to about 20 nt, from about 7 nt to about 15 nt, from about 8 nt to about 40 nt, from about 8 nt to about 30 nt, from about 8 nt to about 25 nt, from about 8 nt to about 20 nt, from about 8 nt to about 15 nt, from about 15 nt to about 100 nt, from about 15 nt to about 80 nt, from about 15 nt to about 50 nt, from about 15 nt to about 40 nt, from about 15 nt to about 30 nt or from about 15 nt to about 25 nt long. The minimum tracrRNA sequence can be approximately 9 nucleotides in length. The minimum tracrRNA sequence can be approximately 12 nucleotides. The minimum tracrRNA can consist of tracrRNA nt 23-48 described in Jinek et al, supra.

[000337] The minimum tracrRNA sequence can be at least about 60% identical to a reference minimum tracrRNA (e.g., wild type, tracrRNA from S. pyogenes) sequence over a stretch of at least 6, 7, or 8 contiguous nucleotides. For example, the minimum tracrRNA sequence can be at least about 65% identical, about 70% identical, about 75% identical, about 80% identical, about 85% identical, about 90% identical, about 95% identical, about 98% identical, about 99% identical or 100% identical to a reference minimum tracrRNA sequence over a stretch of at least 6, 7, or 8 contiguous nucleotides.

[000338] The duplex between the minimum CRISPR RNA and the minimum tracrRNA can comprise a double helix. The duplex between the minimum CRISPR RNA and the minimum tracrRNA can comprise at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more nucleotides. The duplex between the minimum CRISPR RNA and the minimum tracrRNA can comprise at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more nucleotides.

[000339] The duplex can comprise a mismatch (i.e. , the two strands of the duplex are not 100% complementary). The duplex can comprise at least about 1, 2, 3, 4, or 5 or mismatches. The duplex can comprise at most about 1, 2, 3, 4, or 5 or mismatches. The duplex can comprise no more than 2 mismatches.

[000340] Bulges

[000341] In some cases, there can be a“bulge” in the duplex between the minimum CRISPR RNA and the minimum tracrRNA. A bulge is an unpaired region of nucleotides within the duplex. A bulge can contribute to the binding of the duplex to the site-directed polypeptide. The bulge can comprise, on one side of the duplex, an unpaired 5'-XXXY-3' where X is any purine and Y comprises a nucleotide that can form a wobble pair with a nucleotide on the opposite strand, and an unpaired nucleotide region on the other side of the duplex. The number of unpaired nucleotides on the two sides of the duplex can be different.

[000342] In one example, the bulge can comprise an unpaired purine (e.g., adenine) on the minimum CRISPR repeat strand of the bulge. In some examples, the bulge can comprise an unpaired 5'-AAGY-3' of the minimum tracrRNA sequence strand of the bulge, where Y comprises a nucleotide that can form a wobble pairing with a nucleotide on the minimum CRISPR repeat strand.

[000343] A bulge on the minimum CRISPR repeat side of the duplex can comprise at least 1, 2, 3, 4, or 5 or more unpaired nucleotides. A bulge on the minimum CRISPR repeat side of the duplex can comprise at most 1, 2, 3, 4, or 5 or more unpaired nucleotides. A bulge on the minimum CRISPR repeat side of the duplex can comprise 1 unpaired nucleotide.

[000344] A bulge on the minimum tracrRNA sequence side of the duplex can comprise at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more unpaired nucleotides. A bulge on the minimum tracrRNA sequence side of the duplex can comprise at most 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 or more unpaired nucleotides. A bulge on a second side of the duplex (e.g., the minimum tracrRNA sequence side of the duplex) can comprise 4 unpaired nucleotides.

[000345] A bulge can comprise at least one wobble pairing. In some examples, a bulge can comprise at most one wobble pairing. A bulge can comprise at least one purine nucleotide. A bulge can comprise at least 3 purine nucleotides. A bulge sequence can comprise at least 5 purine nucleotides. A bulge sequence can comprise at least one guanine nucleotide. In some examples, a bulge sequence can comprise at least one adenine nucleotide.

[000346] Hairpins

[000347] In various examples, one or more hairpins can be located 3' to the minimum tracrRNA in the 3' tracrRNA sequence.

[000348] The hairpin can start at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 or more nucleotides 3' from the last paired nucleotide in the minimum CRISPR repeat and minimum tracrRNA sequence duplex. The hairpin can start at most about 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 or more nucleotides 3' of the last paired nucleotide in the minimum CRISPR repeat and minimum tracrRNA sequence duplex. [000349] The hairpin can comprise at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or 20 or more consecutive nucleotides. The hairpin can comprise at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, or more consecutive nucleotides.

[000350] The hairpin can comprise a CC dinucleotide (/. e. , two consecutive cytosine nucleotides).

[000351] The hairpin can comprise duplexed nucleotides (e.g., nucleotides in a hairpin, hybridized together). For example, a hairpin can comprise a CC dinucleotide that is hybridized to a GG dinucleotide in a hairpin duplex of the 3' tracrRNA sequence.

[000352] One or more of the hairpins can interact with guide RNA-interacting regions of a site- directed polypeptide.

[000353] In some examples, there are two or more hairpins, and in other examples there are three or more hairpins.

[000354] 3' tracrRNA sequence

[000355] A 3' tracrRNA sequence can comprise a sequence with at least about 30%, about 40%, about 50%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, or 100% sequence identity to a reference tracrRNA sequence (e.g., a tracrRNA from S. pyogenes).

[000356] The 3' tracrRNA sequence can have a length from about 6 nucleotides to about 100 nucleotides. For example, the 3' tracrRNA sequence can have a length from about 6 nucleotides (nt) to about 50 nt, from about 6 nt to about 40 nt, from about 6 nt to about 30 nt, from about 6 nt to about 25 nt, from about 6 nt to about 20 nt, from about 6 nt to about 15 nt, from about 8 nt to about 40 nt, from about 8 nt to about 30 nt, from about 8 nt to about 25 nt, from about 8 nt to about 20 nt, from about 8 nt to about 15 nt, from about 15 nt to about 100 nt, from about 15 nt to about 80 nt, from about 15 nt to about 50 nt, from about 15 nt to about 40 nt, from about 15 nt to about 30 nt, or from about 15 nt to about 25 nt. The 3' tracrRNA sequence can have a length of approximately 14 nucleotides.

[000357] The 3' tracrRNA sequence can be at least about 60% identical to a reference 3' tracrRNA sequence (e.g., wild type 3' tracrRNA sequence from S. pyogenes) over a stretch of at least 6, 7, or 8 contiguous nucleotides. For example, the 3' tracrRNA sequence can be at least about 60% identical, about 65% identical, about 70% identical, about 75% identical, about 80% identical, about 85% identical, about 90% identical, about 95% identical, about 98% identical, about 99% identical, or 100% identical, to a reference 3' tracrRNA sequence (e.g., wild type 3' tracrRNA sequence from S. pyogenes) over a stretch of at least 6, 7, or 8 contiguous nucleotides. [000358] The 3' tracrRNA sequence can comprise more than one duplexed region (e.g., hairpin, hybridized region). The 3' tracrRNA sequence can comprise two duplexed regions.

[000359] The 3' tracrRNA sequence can comprise a stem loop structure. The stem loop structure in the 3' tracrRNA can comprise at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15 or 20 or more nucleotides. The stem loop structure in the 3' tracrRNA can comprise at most 1, 2, 3, 4, 5, 6, 7,

8, 9 or 10 or more nucleotides. The stem loop structure can comprise a functional moiety. For example, the stem loop structure can comprise an aptamer, a ribozyme, a protein-interacting hairpin, a CRISPR array, an intron, or an exon. The stem loop structure can comprise at least about 1, 2, 3, 4, or 5 or more functional moieties. The stem loop structure can comprise at most about 1, 2, 3, 4, or 5 or more functional moieties.

[000360] The hairpin in the 3' tracrRNA sequence can comprise a P-domain. In some examples, the P-domain can comprise a double-stranded region in the hairpin.

[000361] tracrRNA Extension Sequence

[000362] A tracrRNA extension sequence can be provided whether the tracrRNA is in the context of single-molecule guides or double-molecule guides. The tracrRNA extension sequence can have a length from about 1 nucleotide to about 400 nucleotides. The tracrRNA extension sequence can have a length of more than 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, or 400 nucleotides. The tracrRNA extension sequence can have a length from about 20 to about 5000 or more nucleotides. The tracrRNA extension sequence can have a length of more than 1000 nucleotides. The tracrRNA extension sequence can have a length of less than 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380,

400 or more nucleotides. The tracrRNA extension sequence can have a length of less than 1000 nucleotides. The tracrRNA extension sequence can comprise less than 10 nucleotides in length. The tracrRNA extension sequence can be 10-30 nucleotides in length. The tracrRNA extension sequence can be 30-70 nucleotides in length.

[000363] The tracrRNA extension sequence can comprise a functional moiety (e.g., a stability control sequence, ribozyme, endoribonuclease binding sequence). The functional moiety can comprise a transcriptional terminator segment (/. e. , a transcription termination sequence). The functional moiety can have a total length from about 10 nucleotides (nt) to about 100

nucleotides, from about 10 nt to about 20 nt, from about 20 nt to about 30 nt, from about 30 nt to about 40 nt, from about 40 nt to about 50 nt, from about 50 nt to about 60 nt, from about 60 nt to about 70 nt, from about 70 nt to about 80 nt, from about 80 nt to about 90 nt, or from about 90 nt to about 100 nt, from about 15 nt to about 80 nt, from about 15 nt to about 50 nt, from about 15 nt to about 40 nt, from about 15 nt to about 30 nt, or from about 15 nt to about 25 nt. The functional moiety can function in a eukaryotic cell. The functional moiety can function in a prokaryotic cell. The functional moiety can function in both eukaryotic and prokaryotic cells.

[000364] Non-limiting examples of suitable tracrRNA extension functional moieties include a 3' poly-adenylated tail, a riboswitch sequence (e.g., to allow for regulated stability and/or regulated accessibility by proteins and protein complexes), a sequence that forms a dsRNA duplex (/. e. , a hairpin), a sequence that targets the RNA to a subcellular location (e.g. , nucleus, mitochondria, chloroplasts, and the like), a modification or sequence that provides for tracking (e.g. , direct conjugation to a fluorescent molecule, conjugation to a moiety that facilitates fluorescent detection, a sequence that allows for fluorescent detection, etc.), and/or a

modification or sequence that provides a binding site for proteins (e.g., proteins that act on DNA, including transcriptional activators, transcriptional repressors, DNA methyltransferases, DNA demethylases, histone acetyltransferases, histone deacetylases, and the like). The tracrRNA extension sequence can comprise a primer binding site or a molecular index (e.g., barcode sequence). The tracrRNA extension sequence can comprise one or more affinity tags.

[000365] Single-Molecule Guide Linker Sequence

[000366] The linker sequence of a single -molecule guide nucleic acid can have a length from about 3 nucleotides to about 100 nucleotides. In Jinek et al, supra, for example, a simple 4 nucleotide "tetraloop" (-GAAA-) was used, Science, 337(6096):8 l6-82l (2012). An illustrative linker has a length from about 3 nucleotides (nt) to about 90 nt, from about 3 nt to about 80 nt, from about 3 nt to about 70 nt, from about 3 nt to about 60 nt, from about 3 nt to about 50 nt, from about 3 nt to about 40 nt, from about 3 nt to about 30 nt, from about 3 nt to about 20 nt, from about 3 nt to about 10 nt. For example, the linker can have a length from about 3 nt to about 5 nt, from about 5 nt to about 10 nt, from about 10 nt to about 15 nt, from about 15 nt to about 20 nt, from about 20 nt to about 25 nt, from about 25 nt to about 30 nt, from about 30 nt to about 35 nt, from about 35 nt to about 40 nt, from about 40 nt to about 50 nt, from about 50 nt to about 60 nt, from about 60 nt to about 70 nt, from about 70 nt to about 80 nt, from about 80 nt to about 90 nt, or from about 90 nt to about 100 nt. The linker of a single-molecule guide nucleic acid can be between 4 and 40 nucleotides. The linker can be at least about 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, or 7000 or more nucleotides. The linker can be at most about 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, or 7000 or more nucleotides. [000367] Linkers can comprise any of a variety of sequences, although in some examples the linker will not comprise sequences that have extensive regions of homology with other portions of the guide RNA, which might cause intramolecular binding that could interfere with other functional regions of the guide. In Jinek et al, supra, a simple 4 nucleotide sequence -GAAA- was used, Science, 337(6096):8l6-82l (2012), but numerous other sequences, including longer sequences can likewise be used.

[000368] The linker sequence can comprise a functional moiety. For example, the linker sequence can comprise one or more features, including an aptamer, a ribozyme, a protein interacting hairpin, a protein binding site, a CRISPR array, an intron, or an exon. The linker sequence can comprise at least about 1, 2, 3, 4, or 5 or more functional moieties. In some examples, the linker sequence can comprise at most about 1, 2, 3, 4, or 5 or more functional moieties.

[000369] Complexes of a Genome-targeting Nucleic Acid and a Site-Directed Polypeptide

[000370] A genome-targeting nucleic acid interacts with a site-directed polypeptide (e.g., a nucleic acid-guided nuclease such as Cas9), thereby forming a complex. The genome -targeting nucleic acid guides the site-directed polypeptide to a target nucleic acid.

[000371] Ribonucleoprotein complexes (RNPs)

[000372] The site-directed polypeptide and genome -targeting nucleic acid can each be administered separately to a cell or a patient. On the other hand, the site-directed polypeptide can be pre-complexed with one or more guide RNAs, or one or more crRNA together with a tracrRNA. The site-directed polypeptide can be pre-complexed with one or more sgRNA. The pre-complexed material can then be administered to a cell or a patient. Such pre-complexed material is known as a ribonucleoprotein particle (RNP). The site-directed polypeptide in the RNP can be, for example, a Cas9 endonuclease or a Cpfl endonuclease. The site-directed polypeptide can be flanked at the N-terminus, the C-terminus, or both the N-terminus and C- terminus by one or more nuclear localization signals (NLSs). For example, a Cas9 endonuclease can be flanked by two NLSs, one NLS located at the N-terminus and the second NLS located at the C-terminus. The NLS can be any NLS known in the art, such as a SV40 NLS. The weight ratio of genome-targeting nucleic acid to site-directed polypeptide in the RNP can be 1: 1. For example, the weight ratio of sgRNA to Cas9 endonuclease in the RNP can be 1: 1.

[000373] Target Sequence Selection

[000374] Shifts in the location of the 5' boundary and/or the 3' boundary relative to particular reference loci can be used to facilitate or enhance particular applications of gene editing, which depend in part on the endonuclease system selected for the editing, as further described and illustrated herein.

[000375] In a first non-limiting example of such target sequence selection, many endonuclease systems have rules or criteria that can guide the initial selection of potential target sites for cleavage, such as the requirement of a PAM sequence motif in a particular position adjacent to the DNA cleavage sites in the case of CRISPR Type II or Type V endonucleases.

[000376] In another nonlimiting example of target sequence selection or optimization, the frequency of off-target activity for a particular combination of target sequence and gene editing endonuclease can be assessed relative to the frequency of on-target activity. In some cases, cells that have been correctly edited at the desired locus can have a selective advantage relative to other cells. Illustrative, but nonlimiting, examples of a selective advantage include the acquisition of attributes such as enhanced rates of replication, persistence, resistance to certain conditions, enhanced rates of successful engraftment or persistence in vivo following introduction into a patient, and other attributes associated with the maintenance or increased numbers or viability of such cells. In other cases, cells that have been correctly edited at the desired locus can be positively selected for by one or more screening methods used to identify, sort or otherwise select for cells that have been correctly edited. Both selective advantage and directed selection methods can take advantage of the phenotype associated with the correction.

In some cases, cells can be edited two or more times in order to create a second modification that creates a new phenotype that is used to select or purify the intended population of cells. Such a second modification could be created by adding a second gRNA for a selectable or screenable marker. In some cases, cells can be correctly edited at the desired locus using a DNA fragment that contains the cDNA and also a selectable marker.

[000377] Whether any selective advantage is applicable or any directed selection is to be applied in a particular case, target sequence selection can also be guided by consideration of off- target frequencies in order to enhance the effectiveness of the application and/or reduce the potential for undesired alterations at sites other than the desired target. As described further and illustrated herein and in the art, the occurrence of off-target activity can be influenced by a number of factors including similarities and dissimilarities between the target site and various off-target sites, as well as the particular endonuclease used. Bioinformatics tools are available that assist in the prediction of off-target activity, and frequently such tools can also be used to identify the most likely sites of off-target activity, which can then be assessed in experimental settings to evaluate relative frequencies of off-target to on-target activity, thereby allowing the selection of sequences that have higher relative on-target activities. Illustrative examples of such techniques are provided herein, and others are known in the art.

[000378] gRNAs of the present disclosure can direct editing at a genetic locus where editing is desired (e.g., a mutant allele of the GUCY2D gene). As used herein,“on-target editing,”“on- target activity,” or“on-target cleavage” means editing at a genetic locus where editing is desired. A R838S gRNA, a R838C gRNA, a R838H gRNA, a double mutation R838CH gRNA, or a double mutation R838SH gRNA has on-target activity when the gRNA directs editing of the corresponding mutant allele (or mutant alleles in the case of double mutation gRNAs) at or near the R838 position.

[000379] gRNAs of the present disclosure can also direct editing at a genetic locus where editing is not desired. As used herein,“off-target editing,”“off-target activity,” or“off-target cleavage” means editing at a genetic locus where editing is not desired.

[000380] Off-target editing can be editing of a wild-type allele of the GUCY2D gene. Herein, this type of off-target editing is termed“wild-type off-target editing,”“wild-type off-target activity,” or“wild-type off-target cleavage.” A R838S gRNA, a R838C gRNA, a R838H gRNA, a double mutation R838CH gRNA, or a double mutation R838SH gRNA can have wild-type off- target activity when the gRNA directs editing of a wild-type GUCY2D allele.

[000381] Off-target editing can be editing of a second gene or locus (e.g., editing of a genomic sequence that is not a sequence of the GUCY2D gene or a regulatory sequence of the GUCY2D gene). Herein, this type of off-target editing is termed“genomic off-target editing,”“genomic off-target activity,” or“genomic off-target cleavage.” A R838S gRNA, a R838C gRNA, a R838H gRNA, a double mutation R838CH gRNA, or a double mutation R838SH gRNA has genomic off-target activity when the gRNA directs editing of a genomic sequence that is not a sequence of the GUCY2D gene or a regulatory sequence of the GUCY2D gene.

[000382] In some examples, wild-type off-target activity of a gRNA can be“minimal.” gRNAs with minimal wild-type off-target activity can be determined using methods known in the art, for example, methods based on in silico analysis, in vitro methods, or in vivo methods of determining the amount of wild-type off-target editing caused by a gRNA. A gRNA with minimal wild-type off-target activity can cause off-target editing in 30% or less of cells, for example, 25% or less of cells, 20% or less of cells, 15% or less of cells 10% or less of cells, 5% or less of cells, 4% or less of cells, 3% or less of cells, 2% or less of cells, 1% or less of cells, 0.5% or less of cells, 0.25% or less of cells, or 0.1% or less of cells. Such determinations can, in some cases, be determined using in vitro systems. [000383] In some examples, genomic off-target activity of a gRNA can be“minimal.” gRNAs with minimal genomic off-target activity can be determined based on in silico analysis, in vitro methods, or in vivo methods of determining the amount of genomic off-target editing caused by a gRNA. A gRNA with minimal genomic off-target activity can cause at least one instance of genomic off-target editing in 30% or less of cells such as, for example, 25% or less of cells, 20% or less of cells, 15% or less of cells 10% or less of cells, 5% or less of cells, 4% or less of cells, 3% or less of cells, 2% or less of cells, 1% or less of cells, 0.5% or less of cells, 0.25% or less of cells, or 0.1% or less of cells. Such determinations can, in some cases, be determined using in vitro systems.

[000384] Another aspect of target sequence selection relates to homologous recombination events. Sequences sharing regions of homology can serve as focal points for homologous recombination events that result in deletion of intervening sequences. Such recombination events occur during the normal course of replication of chromosomes and other DNA sequences, and also at other times when DNA sequences are being synthesized, such as in the case of repairs of DSBs, which occur on a regular basis during the normal cell replication cycle but can also be enhanced by the occurrence of various events (such as UV light and other inducers of DNA breakage) or the presence of certain agents (such as various chemical inducers). Many such inducers cause DSBs to occur indiscriminately in the genome, and DSBs can be regularly induced and repaired in normal cells. During repair, the original sequence can be reconstructed with complete fidelity, however, in some cases, small insertions or deletions (referred to as "indels") are introduced at the DSB site.

[000385] DSBs can also be specifically induced at particular locations, as in the case of the endonucleases systems described herein, which can be used to cause directed or preferential gene modification events at selected chromosomal locations. The tendency for homologous sequences to be subject to recombination in the context of DNA repair (as well as replication) can be taken advantage of in a number of circumstances, and is the basis for one application of gene editing systems, such as CRISPR, in which homology directed repair is used to insert a sequence of interest, provided through use of a "donor" polynucleotide, into a desired chromosomal location.

[000386] Regions of homology between particular sequences, which can be small regions of "microhomology" that can comprise as few as ten base pairs or less, can also be used to bring about desired deletions. For example, a single DSB can be introduced at a site that exhibits microhomology with a nearby sequence. During the normal course of repair of such DSB, a result that occurs with high frequency is the deletion of the intervening sequence as a result of recombination being facilitated by the DSB and concomitant cellular repair process.

[000387] In some circumstances, however, selecting target sequences within regions of homology can also give rise to much larger deletions, including gene fusions (when the deletions are in coding regions), which may or may not be desired given the particular circumstances.

[000388] The examples provided herein further illustrate the selection of various target regions for the creation of DSBs designed to induce replacements that result in restoration of RetGC 1 protein activity, as well as the selection of specific target sequences within such regions that are designed to minimize off-target events relative to on-target events.

[000389] Homology direct Repair (HDR) / Donor nucleotides

[000390] Homology direct repair is a cellular mechanism for repairing DSBs. The most common form is homologous recombination. There are additional pathways for HDR, including single-strand annealing and altemative-HDR. Genome engineering tools allow researchers to manipulate the cellular homologous recombination pathways to create site-specific modifications to the genome. It has been found that cells can repair a double-stranded break using a synthetic donor molecule provided in trans. Therefore, by introducing a double-stranded break near a specific mutation and providing a suitable donor, targeted changes can be made in the genome. Specific cleavage increases the rate of HDR more than 1,000 fold above the rate of 1 in 10 ⁶ cells receiving a homologous donor alone. The rate of HDR at a particular nucleotide is a function of the distance to the cut site, so choosing overlapping or nearest target sites is important. Gene editing offers the advantage over gene addition, as correcting in situ leaves the rest of the genome unperturbed.

[000391] Supplied donors for editing by HDR vary markedly but can contain the intended sequence with small or large flanking homology arms to allow annealing to the genomic DNA. The homology regions flanking the introduced genetic changes can be 30 bp or smaller, or as large as a multi-kilobase cassette that can contain promoters, cDNAs, etc. Both single -stranded and double -stranded oligonucleotide donors have been used. These oligonucleotides range in size from less than 100 nt to over many kb, though longer ssDNA can also be generated and used. Double -stranded donors can be used, including PCR amplicons, plasmids, and mini circles. In general, it has been found that an AAV vector can be a very effective means of delivery of a donor template, though the packaging limits for individual donors is <5kb. Active transcription of the donor increased HDR three-fold, indicating the inclusion of promoter may increase conversion. Conversely, CpG methylation of the donor decreased gene expression and HDR.

[000392] Donor nucleotides for correcting mutations often are small (< 300 bp). This is advantageous, as HDR efficiencies may be inversely related to the size of the donor molecule. Also, it is expected that the donor templates can fit into size constrained AAV molecules, which have been shown to be an effective means of donor template delivery.

[000393] In addition to wildtype endonucleases, such as Cas9, nickase variants exist that have one or the other nuclease domain inactivated resulting in cutting of only one DNA strand. HDR can be directed from individual Cas nickases or using pairs of nickases that flank the target area. Donors can be single-stranded, nicked, or dsDNA.

[000394] The donor DNA can be supplied with the nuclease or independently by a variety of different methods, for example by transfection, nanoparticle, microinjection, or viral transduction. A range of tethering options has been proposed to increase the availability of the donors for HDR. Examples include attaching the donor to the nuclease, attaching to DNA binding proteins that bind nearby, or attaching to proteins that are involved in DNA end binding or repair.

[000395] The repair pathway choice can be guided by a number of culture conditions, such as those that influence cell cycling, or by targeting of DNA repair and associated proteins. For example, to increase HDR, key NHEJ molecules can be suppressed, such as KU70, KU80 or DNA ligase IV.

[000396] Without a donor present, the ends from a DNA break or ends from different breaks can be joined using the several non-homologous repair pathways in which the DNA ends are joined with little or no base -pairing at the junction. In addition to canonical NHEJ, there are similar repair mechanisms, such as ANHEJ. If there are two breaks, the intervening segment can be deleted or inverted. NHEJ repair pathways can lead to insertions, deletions or mutations at the joints.

[000397] NHEJ was used to insert a 15 -kb inducible gene expression cassette into a defined locus in human cell lines after nuclease cleavage. The methods of insertion of large inducible gene expression cassettes have been described [Maresca, M., Lin, V.G., Guo, N. & Yang, Y., Genome Res 23, 539-546 (2013), Suzuki et al. Nature , 540, 144-149 (2016))].

[000398] In addition to genome editing by NHEJ or HDR, site-specific gene insertions have been conducted that use both the NHEJ pathway and HDR. A combination approach can be applicable in certain settings, possibly including intron/exon borders. NHEJ may prove effective for ligation in the intron, while the error-free HDR may be better suited in the coding region.

[000399] Illustrative modifications within the GUCY2D gene include replacements within or near (proximal) to the mutations referred to above (i.e. R838H, R838C, or R838S mutations), such as within the region of less than 3 kb, less than 2kb, less than 1 kb, less than 0.5 kb upstream or downstream of the specific mutation. Given the relatively wide variations of mutations in the GUCY2D gene, it will be appreciated that numerous variations of the replacements referenced above (including without limitation larger as well as smaller deletions), would be expected to result in restoration of the RetGCl protein activity.

[000400] Such variants can include replacements that are larger in the 5' and/or 3' direction than the specific mutation in question, or smaller in either direction. Accordingly, by“near” or "proximal" with respect to specific replacements, it is intended that the SSB or DSB locus associated with a desired replacement boundary (also referred to herein as an endpoint) can be within a region that is less than about 3 kb from the reference locus, e.g., the mutation site. The SSB or DSB locus can be more proximal and within 2 kb, within 1 kb, within 0.5 kb, or within 0.1 kb. In the case of a small replacement, the desired endpoint can be at or "adjacent to" the reference locus, by which it is intended that the endpoint can be within 100 bp, within 50 bp, within 25 bp, or less than about 10 bp to 5 bp from the reference locus.

[000401] Larger or smaller replacements can provide the same benefit, as long as the RetGCl protein activity is restored. It is thus expected that many variations of the replacements described and illustrated herein can be effective for ameliorating autosomal dominant CORD.

[000402] The terms“near” or“proximal” with respect to the SSBs or DSBs refer to the SSBs or DSBs being within 2 kb, within 1 kb, within 0.5 kb, within 0.25 kb, within 0.2 kb, or within 0.1 kb of the R838H, R838C, or R838S mutation.

[000403] Nucleic acid modifications (chemical and structural modifications)

[000404] In some cases, polynucleotides introduced into cells can comprise one or more modifications that can be used individually or in combination, for example, to enhance activity, stability or specificity, alter delivery, reduce innate immune responses in host cells, or for other enhancements, as further described herein and known in the art.

[000405] In certain examples, modified polynucleotides can be used in the CRISPR Cas9/Cpfl system, in which case the guide RNAs (either single-molecule guides or double-molecule guides) and/or a DNA or an RNA encoding a Cas or Cpfl endonuclease introduced into a cell can be modified, as described and illustrated below. Such modified polynucleotides can be used in the CRISPR/Cas9/Cpfl system to edit any one or more genomic loci.

[000406] Using the CRISPR/Cas9/Cpfl system for purposes of non-limiting illustrations of such uses, modifications of guide RNAs can be used to enhance the formation or stability of the CRISPR/Cas9/Cpfl genome editing complex comprising guide RNAs, which can be single molecule guides or double-molecule, and a Cas or Cpfl endonuclease. Modifications of guide RNAs can also or alternatively be used to enhance the initiation, stability or kinetics of interactions between the genome editing complex with the target sequence in the genome, which can be used, for example, to enhance on-target activity. Modifications of guide RNAs can also or alternatively be used to enhance specificity, e.g. , the relative rates of genome editing at the on- target site as compared to effects at other (off-target) sites.

[000407] Modifications can also or alternatively be used to increase the stability of a guide RNA, e.g., by increasing its resistance to degradation by ribonucleases (RNases) present in a cell, thereby causing its half-life in the cell to be increased. Modifications enhancing guide RNA half-life can be particularly useful in aspects in which a Cas or Cpfl endonuclease is introduced into the cell to be edited via an RNA that needs to be translated in order to generate

endonuclease, because increasing the half-life of guide RNAs introduced at the same time as the RNA encoding the endonuclease can be used to increase the time that the guide RNAs and the encoded Cas or Cpfl endonuclease co-exist in the cell.

[000408] Modifications can also or alternatively be used to decrease the likelihood or degree to which RNAs introduced into cells elicit innate immune responses. Such responses, which have been well characterized in the context of RNA interference (RNAi), including small-interfering RNAs (siRNAs), as described below and in the art, tend to be associated with reduced half-life of the RNA and/or the elicitation of cytokines or other factors associated with immune responses.

[000409] One or more types of modifications can also be made to RNAs encoding an endonuclease that are introduced into a cell, including, without limitation, modifications that enhance the stability of the RNA (such as by increasing its degradation by RNAses present in the cell), modifications that enhance translation of the resulting product (i.e. the endonuclease), and/or modifications that decrease the likelihood or degree to which the RNAs introduced into cells elicit innate immune responses.

[000410] Combinations of modifications, such as the foregoing and others, can likewise be used. In the case of CRISPR/Cas9/Cpfl, for example, one or more types of modifications can be made to guide RNAs (including those exemplified above), and/or one or more types of modifications can be made to RNAs encoding Cas endonuclease (including those exemplified above).

[000411] By way of illustration, guide RNAs used in the CRISPR/Cas9/Cpfl system, or other smaller RNAs can be readily synthesized by chemical means, enabling a number of

modifications to be readily incorporated, as illustrated below and described in the art. While chemical synthetic procedures are continually expanding, purifications of such RNAs by procedures such as high-performance liquid chromatography (HPLC, which avoids the use of gels such as PAGE) tends to become more challenging as polynucleotide lengths increase significantly beyond a hundred or so nucleotides. One approach that can be used for generating chemically modified RNAs of greater length is to produce two or more molecules that are ligated together. Much longer RNAs, such as those encoding a Cas9 endonuclease, are more readily generated enzymatically. While fewer types of modifications are available for use in enzymatically produced RNAs, there are still modifications that can be used to, e.g., enhance stability, reduce the likelihood or degree of innate immune response, and/or enhance other attributes, as described further below and in the art; and new types of modifications are regularly being developed.

[000412] By way of illustration of various types of modifications, especially those used frequently with smaller chemically synthesized RNAs, modifications can comprise one or more nucleotides modified at the 2' position of the sugar, in some aspects a 2'-0-alkyl, 2'-0-alkyl-0- alkyl, or 2'-fluoro-modified nucleotide. In some examples, RNA modifications can comprise 2'- fluoro, 2'-amino or 2'-0-methyl modifications on the ribose of pyrimidines, abasic residues, or an inverted base at the 3' end of the RNA. Such modifications can be routinely incorporated into oligonucleotides and these oligonucleotides have been shown to have a higher Tm (i.e., higher target binding affinity) than 2'-deoxyoligonucleotides against a given target.

[000413] A number of nucleotide and nucleoside modifications have been shown to make the oligonucleotide into which they are incorporated more resistant to nuclease digestion than the native oligonucleotide; these modified oligos survive intact for a longer time than unmodified oligonucleotides. Specific examples of modified oligonucleotides include those comprising modified backbones, for example, phosphorothioates, phosphotriesters, methyl phosphonates, short chain alkyl or cycloalkyl intersugar linkages or short chain heteroatomic or heterocyclic intersugar linkages. Some oligonucleotides are oligonucleotides with phosphorothioate backbones and those with heteroatom backbones, particularly CH2-NH-O-CH2,

CH,~N(CH3)~0~CH2 (known as a methylene (methylimino) or MMI backbone), CH2-O-N (CH ₃ )-CH ₂ , CH2 -N (CTU)-N (CH ₃ )-CH ₂ and O-N (CH ₃ )- CH ₂ -CH ₂ backbones, wherein the native phosphodiester backbone is represented as O- P- O- CH,); amide backbones [see De Mesmaeker et al., Ace. Chem. Res., 28:366-374 (1995)]; morpholino backbone structures (see Summerton and Weller, U.S. Patent No. 5,034,506); peptide nucleic acid (PNA) backbone (wherein the phosphodiester backbone of the oligonucleotide is replaced with a polyamide backbone, the nucleotides being bound directly or indirectly to the aza nitrogen atoms of the polyamide backbone, see Nielsen et al., Science 1991, 254, 1497). Phosphorus-containing linkages include, but are not limited to, phosphorothioates, chiral phosphorothioates, phosphorodithioates, phosphotriesters, aminoalkylphosphotriesters, methyl and other alkyl phosphonates comprising 3'alkylene phosphonates and chiral phosphonates, phosphinates, phosphoramidates comprising 3'-amino phosphoramidate and aminoalkylphosphoramidates, thionophosphoramidates, thionoalkylphosphonates, thionoalkylphosphotriesters, and boranophosphates having normal 3'-5' linkages, 2'-5' linked analogs of these, and those having inverted polarity wherein the adjacent pairs of nucleoside units are linked 3'-5' to 5'-3' or 2'-5' to 5'-2'; see U.S. Patent Nos. 3,687,808; 4,469,863; 4,476,301; 5,023,243; 5,177,196; 5,188,897; 5,264,423; 5,276,019; 5,278,302; 5,286,717; 5,321,131; 5,399,676; 5,405,939; 5,453,496;

5,455,233; 5,466,677; 5,476,925; 5,519,126; 5,536,821; 5,541,306; 5,550,111; 5,563,253;

5,571,799; 5,587,361; and 5,625,050.

[000414] Morpholino-based oligomeric compounds are described in Braasch and David Corey, Biochemistry, 41(14): 4503-4510 (2002); Genesis, Volume 30, Issue 3, (2001); Heasman, Dev. Biol., 243: 209-214 (2002); Nasevicius et al., Nat. Genet., 26:216-220 (2000); Lacerra et al., Proc. Natl. Acad. Sci., 97: 9591-9596 (2000); and U.S. Patent No. 5,034,506, issued Jul. 23,

1991.

[000415] Cyclohexenyl nucleic acid oligonucleotide mimetics are described in Wang et al., J. Am. Chem. Soc., 122: 8595-8602 (2000).

[000416] Modified oligonucleotide backbones that do not include a phosphorus atom therein have backbones that are formed by short chain alkyl or cycloalkyl intemucleoside linkages, mixed heteroatom and alkyl or cycloalkyl intemucleoside linkages, or one or more short chain heteroatomic or heterocyclic intemucleoside linkages. These comprise those having morpholino linkages (formed in part from the sugar portion of a nucleoside); siloxane backbones; sulfide, sulfoxide and sulfone backbones; formacetyl and thioformacetyl backbones; methylene formacetyl and thioformacetyl backbones; alkene containing backbones; sulfamate backbones; methyleneimino and methylenehydrazino backbones; sulfonate and sulfonamide backbones; amide backbones; and others having mixed N, O, S, and CH2 component parts; see U.S. Patent Nos. 5,034,506; 5,166,315; 5,185,444; 5,214,134; 5,216,141; 5,235,033; 5,264,562; 5,264,564; 5,405,938; 5,434,257; 5,466,677; 5,470,967; 5,489,677; 5,541,307; 5,561,225; 5,596,086;

5,602,240; 5,610,289; 5,602,240; 5,608,046; 5,610,289; 5,618,704; 5,623,070; 5,663,312;

5,633,360; 5,677,437; and 5,677,439.

[000417] One or more substituted sugar moieties can also be included, e.g., one of the following at the 2' position: OH, SH, SCH ₃ , F, OCN, OCH3 OCH3, OCH3 0(CH ₂ )n CH ₃ , 0(CH ₂ )n NH ₂ , or 0(CH ₂ )n CH3, where n is from 1 to about 10; Cl to C 10 lower alkyl, alkoxyalkoxy, substituted lower alkyl, alkaryl or aralkyl; Cl; Br; CN; CF3; OCF3; O-, S-, or N- alkyl; O-, S-, or N-alkenyl; SOCH3; S0 ₂ CH3; ON0 ₂ ; N0 ₂ ; N3; NH ₂ ; heterocycloalkyl;

heterocycloalkaryl; aminoalkylamino; polyalkylamino; substituted silyl; an RNA cleaving group; a reporter group; an intercalator; a group for improving the pharmacokinetic properties of an oligonucleotide; or a group for improving the pharmacodynamic properties of an oligonucleotide and other substituents having similar properties. In some aspects, a modification includes 2'- methoxyethoxy (2'-0-CH ₂ CH ₂ 0CH ₃ , also known as 2'-0-(2-methoxyethyl)) (Martin et al, Helv. Chim. Acta, 1995, 78, 486). Other modifications include 2'-methoxy (2'-0-CH ₃ ), 2'-propoxy (2'- OCH ₂ CH ₂ CH ₃ ) and 2'-fluoro (2'-F). Similar modifications can also be made at other positions on the oligonucleotide, particularly the 3' position of the sugar on the 3' terminal nucleotide and the 5' position of 5' terminal nucleotide. Oligonucleotides can also have sugar mimetics, such as cyclobutyls in place of the pentofuranosyl group.

[000418] In some examples, both a sugar and an intemucleoside linkage, i.e., the backbone, of the nucleotide units can be replaced with novel groups. The base units can be maintained for hybridization with an appropriate nucleic acid target compound. One such oligomeric compound, an oligonucleotide mimetic that has been shown to have excellent hybridization properties, is referred to as a peptide nucleic acid (PNA). In PNA compounds, the sugar- backbone of an oligonucleotide can be replaced with an amide containing backbone, for example, an aminoethylglycine backbone. The nucleobases can be retained and bound directly or indirectly to aza nitrogen atoms of the amide portion of the backbone. Representative U.S. patents that teach the preparation of PNA compounds comprise, but are not limited to, U.S.

Patent Nos. 5,539,082; 5,714,331; and 5,719,262. Further teaching of PNA compounds can be found in Nielsen et al, Science, 254: 1497-1500 (1991).

[000419] Guide RNAs can also include, additionally or alternatively, nucleobase (often referred to in the art simply as "base") modifications or substitutions. As used herein, "unmodified" or "natural" nucleobases include adenine (A), guanine (G), thymine (T), cytosine (C), and uracil (U). Modified nucleobases include nucleobases found only infrequently or transiently in natural nucleic acids, e.g., hypoxanthine, 6-methyladenine, 5-Me pyrimidines, particularly 5- methylcytosine (also referred to as 5 -methyl -2' deoxy cytosine and often referred to in the art as 5-Me-C), 5-hydroxymethylcytosine (HMC), glycosyl HMC and gentobiosyl HMC, as well as synthetic nucleobases, e.g., 2-aminoadenine, 2-(methylamino) adenine, 2- (imidazolylalkyl)adenine, 2-(aminoalklyamino) adenine or other heterosubstituted alkyladenines, 2-thiouracil, 2-thiothymine, 5-bromouracil, 5-hydroxymethyluracil, 8-azaguanine, 7- deazaguanine, N6 (6-aminohexyl) adenine, and 2,6-diaminopurine. Komberg, A., DNA

Replication, W. H. Freeman & Co., San Francisco, pp. 75-77 (1980); Gebeyehu et al., Nucl. Acids Res. 15:4513 (1997). A "universal" base known in the art, e.g., inosine, can also be included. 5-Me-C substitutions have been shown to increase nucleic acid duplex stability by 0.6- 1.2 °C. (Sanghvi, Y. S., in Crooke, S. T. and Lebleu, B., eds., Antisense Research and

Applications, CRC Press, Boca Raton, 1993, pp. 276-278) and are aspects of base substitutions.

[000420] Modified nucleobases can comprise other synthetic and natural nucleobases, such as 5-methylcytosine (5-me-C), 5 -hydroxymethyl cytosine, xanthine, hypoxanthine, 2- aminoadenine, 6-methyl and other alkyl derivatives of adenine and guanine, 2-propyl and other alkyl derivatives of adenine and guanine, 2-thiouracil, 2-thiothymine and 2-thiocytosine, 5- halouracil and cytosine, 5-propynyl uracil and cytosine, 6-azo uracil, cytosine and thymine, 5- uracil (pseudo-uracil), 4-thiouracil, 8-halo, 8-amino, 8-thiol, 8- thioalkyl, 8-hydroxyl and other 8-substituted adenines and guanines, 5-halo particularly 5- bromo, 5-trifluoromethyl and other 5- substituted uracils and cytosines, 7-methylquanine and 7-methyladenine, 8-azaguanine and 8- azaadenine, 7-deazaguanine and 7-deazaadenine, and 3-deazaguanine and 3-deazaadenine.

[000421] Further, nucleobases can comprise those disclosed in U.S. Patent No. 3,687,808, those disclosed in 'The Concise Encyclopedia of Polymer Science and Engineering', pages 858- 859, Kroschwitz, J.I., ed. John Wiley & Sons, 1990, those disclosed by Englisch etal.,

Angewandle Chemie, International Edition', 1991, 30, page 613, and those disclosed by Sanghvi, Y. S., Chapter 15, Antisense Research and Applications', pages 289- 302, Crooke, S.T. and Lebleu, B. ea., CRC Press, 1993. Certain of these nucleobases are particularly useful for increasing the binding affinity of the oligomeric compounds of the invention. These include 5- substituted pyrimidines, 6-azapyrimidines and N-2, N-6 and 0-6 substituted purines, comprising 2-aminopropyladenine, 5-propynyluracil and 5-propynylcytosine. 5-methylcytosine substitutions have been shown to increase nucleic acid duplex stability by 0.6-l.2°C (Sanghvi, Y.S., Crooke, S.T. and Lebleu, B., eds, 'Antisense Research and Applications', CRC Press, Boca Raton, 1993, pp. 276-278) and are aspects of base substitutions, even more particularly when combined with 2'-0-methoxyethyl sugar modifications. Modified nucleobases are described in U.S. Patent No. 3,687,808, as well as 4,845,205; 5,130,302; 5,134,066; 5,175,273; 5,367,066; 5,432,272;

5,457,187; 5,459,255; 5,484,908; 5,502,177; 5,525,711; 5,552,540; 5,587,469; 5,596,091;

5,614,617; 5,681,941; 5,750,692; 5,763,588; 5,830,653; 6,005,096; and U.S. Patent Application Publication 2003/0158403.

[000422] Thus, the term“modified” refers to a non-natural sugar, phosphate, or base that is incorporated into a guide RNA, an endonuclease, or both a guide RNA and an endonuclease. It is not necessary for all positions in a given oligonucleotide to be uniformly modified, and in fact more than one of the aforementioned modifications can be incorporated in a single

oligonucleotide, or even in a single nucleoside within an oligonucleotide.

[000423] The guide RNAs and/or mRNA (or DNA) encoding an endonuclease can be chemically linked to one or more moieties or conjugates that enhance the activity, cellular distribution, or cellular uptake of the oligonucleotide. Such moieties comprise, but are not limited to, lipid moieties such as a cholesterol moiety [Letsinger et al., Proc. Natl. Acad. Sci. USA, 86: 6553-6556 (1989)]; cholic acid [Manoharan et al., Bioorg. Med. Chem. Uet., 4: 1053- 1060 (1994)]; athioether, e.g., hexyl-S- tritylthiol [Manoharan et al, Ann. N. Y. Acad. Sci., 660: 306-309 (1992) and Manoharan et al., Bioorg. Med. Chem. Uet., 3: 2765-2770 (1993)]; a thiocholesterol [Oberhauser etal., Nucl. Acids Res., 20: 533-538 (1992)]; an aliphatic chain, e.g., dodecandiol or undecyl residues [Kabanov et al., FEBS Uett., 259: 327-330 (1990) and Svinarchuk et al., Biochimie, 75: 49- 54 (1993)]; a phospholipid, e.g., di-hexadecyl-rac -glycerol or triethylammonium 1 ,2-di-O-hexadecyl- rac-glycero-3-H-phosphonate [Manoharan et al., Tetrahedron Uett., 36: 3651-3654 (1995) and Shea etal., Nucl. Acids Res., 18: 3777-3783 (1990)]; a polyamine or a polyethylene glycol chain [Manoharan et al., Nucleosides &

Nucleotides, 14: 969-973 (1995)]; adamantane acetic acid [Manoharan et al., Tetrahedron Uett., 36: 3651-3654 (1995)]; a palmityl moiety [(Mishra et al., Biochim. Biophys. Acta, 1264: 229- 237 (1995)]; or an octadecylamine or hexylamino-carbonyl-t oxy cholesterol moiety [Crooke et al., J. Pharmacol. Exp. Ther., 277: 923-937 (1996)]. See also U.S. Patent Nos. 4,828,979;

4,948,882; 5,218,105; 5,525,465; 5,541,313; 5,545,730; 5,552,538; 5,578,717; 5,580,731;

5,580,731; 5,591,584; 5,109,124; 5,118,802; 5,138,045; 5,414,077; 5,486,603; 5,512,439;

5,578,718; 5,608,046; 4,587,044; 4,605,735; 4,667,025; 4,762,779; 4,789,737; 4,824,941;

4,835,263; 4,876,335; 4,904,582; 4,958,013; 5,082,830; 5,112,963; 5,214,136; 5,082,830; 5,112,963; 5,214,136; 5,245,022; 5,254,469; 5,258,506; 5,262,536; 5,272,250; 5,292,873;

5,317,098; 5,371,241; 5,391,723; 5,416,203; 5,451,463; 5,510,475; 5,512,667; 5,514,785;

5,565,552; 5,567,810; 5,574,142; 5,585,481; 5,587,371; 5,595,726; 5,597,696; 5,599,923; 5,599, 928 and 5,688,941.

[000424] Sugars and other moieties can be used to target proteins and complexes comprising nucleotides, such as cationic polysomes and liposomes, to particular sites. For example, hepatic cell directed transfer can be mediated via asialoglycoprotein receptors (ASGPRs); see, e.g., Hu, et al., Protein Pept Lett. 21(10): 1025-30 (2014). Other systems known in the art and regularly developed can be used to target biomolecules of use in the present case and/or complexes thereof to particular target cells of interest.

[000425] These targeting moieties or conjugates can include conjugate groups covalently bound to functional groups, such as primary or secondary hydroxyl groups. Conjugate groups of the present disclosure include intercalators, reporter molecules, polyamines, polyamides, polyethylene glycols, polyethers, groups that enhance the pharmacodynamic properties of oligomers, and groups that enhance the pharmacokinetic properties of oligomers. Typical conjugate groups include cholesterols, lipids, phospholipids, biotin, phenazine, folate, phenanthridine, anthraquinone, acridine, fluoresceins, rhodamines, coumarins, and dyes. Groups that enhance the pharmacodynamic properties, in the context of this present disclosure, include groups that improve uptake, enhance resistance to degradation, and/or strengthen sequence- specific hybridization with the target nucleic acid. Groups that enhance the pharmacokinetic properties, in the context of this invention, include groups that improve uptake, distribution, metabolism or excretion of the compounds of the present disclosure. Representative conjugate groups are disclosed in International Patent Application No. PCT/US92/09196, filed Oct. 23,

1992 (published as WO1993007883), and U.S. Patent No. 6,287,860. Conjugate moieties include, but are not limited to, lipid moieties such as a cholesterol moiety, cholic acid, a thioether, e.g., hexyl-5 -tritylthiol, a thiocholesterol, an aliphatic chain, e.g., dodecandiol or undecyl residues, a phospholipid, e.g., di-hexadecyl-rac- glycerol or triethylammonium 1,2-di-O- hexadecyl-rac-glycero-3-H-phosphonate, a polyamine or a polyethylene glycol chain, or adamantane acetic acid, a palmityl moiety, or an octadecylamine or hexylamino-carbonyl-oxy cholesterol moiety. See, e.g., U.S. Pat. Nos. 4,828,979; 4,948,882; 5,218,105; 5,525,465;

5,541,313; 5,545,730; 5,552,538; 5,578,717, 5,580,731; 5,580,731; 5,591,584; 5,109,124;

5,118,802; 5,138,045; 5,414,077; 5,486,603; 5,512,439; 5,578,718; 5,608,046; 4,587,044;

4,605,735; 4,667,025; 4,762,779; 4,789,737; 4,824,941; 4,835,263; 4,876,335; 4,904,582; 4,958,013; 5,082,830; 5,112,963; 5,214,136; 5,082,830; 5,112,963; 5,214,136; 5,245,022;

5,254,469; 5,258,506; 5,262,536; 5,272,250; 5,292,873; 5,317,098; 5,371,241; 5,391,723;

5,416,203, 5,451,463; 5,510,475; 5,512,667; 5,514,785; 5,565,552; 5,567,810; 5,574,142;

5,585,481; 5,587,371; 5,595,726; 5,597,696; 5,599,923; 5,599,928 and 5,688,941.

[000426] Longer polynucleotides that are less amenable to chemical synthesis and are typically produced by enzymatic synthesis can also be modified by various means. Such modifications can include, for example, the introduction of certain nucleotide analogs, the incorporation of particular sequences or other moieties at the 5' or 3' ends of molecules, and other modifications. By way of illustration, the mRNA encoding Cas9 is approximately 4 kb in length and can be synthesized by in vitro transcription. Modifications to the mRNA can be applied to, e.g., increase its translation or stability (such as by increasing its resistance to degradation with a cell), or to reduce the tendency of the RNA to elicit an innate immune response that is often observed in cells following introduction of exogenous RNAs, particularly longer RNAs such as that encoding Cas9.

[000427] Numerous such modifications have been described in the art, such as polyA tails, 5' cap analogs (e.g., Anti Reverse Cap Analog (ARCA) or m7G(5’)ppp(5’)G (mCAP)), modified 5' or 3' untranslated regions (UTRs), use of modified bases (such as Pseudo-UTP, 2-Thio-UTP, 5- Methylcytidine-5 '-Triphosphate (5-Methyl-CTP) or N6-Methyl-ATP), or treatment with phosphatase to remove 5' terminal phosphates. These and other modifications are known in the art, and new modifications of RNAs are regularly being developed.

[000428] There are numerous commercial suppliers of modified RNAs, including for example, TriLink Biotech, AxoLabs, Bio-Synthesis Inc., Dharmacon and many others. As described by TriLink, for example, 5-Methyl-CTP can be used to impart desirable characteristics, such as increased nuclease stability, increased translation or reduced interaction of innate immune receptors with in vitro transcribed RNA. 5 -Methylcytidine-5 '-Triphosphate (5-Methyl-CTP), N6-Methyl-ATP, as well as Pseudo-UTP and 2-Thio-UTP, have also been shown to reduce innate immune stimulation in culture and in vivo while enhancing translation, as illustrated in publications by Kormann el al. and Warren el al. referred to below.

[000429] It has been shown that chemically modified mRNA delivered in vivo can be used to achieve improved therapeutic effects; see, e.g., Kormann et al., Nature Biotechnology 29, 154— 157 (2011). Such modifications can be used, for example, to increase the stability of the RNA molecule and/or reduce its immunogenicity. Using chemical modifications such as Pseudo-U, N6-Methyl-A, 2-Thio-U and 5-Methyl-C, it was found that substituting just one quarter of the uridine and cytidine residues with 2-Thio-U and 5-Methyl-C respectively resulted in a significant decrease in toll -like receptor (TLR) mediated recognition of the mRNA in mice. By reducing the activation of the innate immune system, these modifications can be used to effectively increase the stability and longevity of the mRNA in vivo ; see, e.g., Kormann el al., supra.

[000430] It has also been shown that repeated administration of synthetic messenger RNAs incorporating modifications designed to bypass innate anti-viral responses can reprogram differentiated human cells to pluripotency. See, e.g., Warren, el al., Cell Stem Cell, 7(5):6l8-30 (2010). Such modified mRNAs that act as primary reprogramming proteins can be an efficient means of reprogramming multiple human cell types. Such cells are referred to as induced pluripotency stem cells (iPSCs), and it was found that enzymatically synthesized RNA incorporating 5-Methyl-CTP, Pseudo-UTP and an Anti Reverse Cap Analog (ARCA) could be used to effectively evade the cell’s antiviral response; see, e.g., Warren et al., supra.

[000431] Other modifications of polynucleotides described in the art include, for example, the use of polyA tails, the addition of 5' cap analogs such as (m7G(5’)ppp(5’)G (mCAP)), modifications of 5' or 3' untranslated regions (UTRs), or treatment with phosphatase to remove 5' terminal phosphates - and new approaches are regularly being developed.

[000432] A number of compositions and techniques applicable to the generation of modified RNAs for use herein have been developed in connection with the modification of RNA interference (RNAi), including small-interfering RNAs (siRNAs). siRNAs present particular challenges in vivo because their effects on gene silencing via mRNA interference are generally transient, which can require repeat administration. In addition, siRNAs are double-stranded RNAs (dsRNA) and mammalian cells have immune responses that have evolved to detect and neutralize dsRNA, which is often a by-product of viral infection. Thus, there are mammalian enzymes such as PKR (dsRNA-responsive kinase), and potentially retinoic acid-inducible gene I (RIG-I), that can mediate cellular responses to dsRNA, as well as Toll-like receptors (such as TLR3, TLR7 and TLR8) that can trigger the induction of cytokines in response to such molecules; see, e.g., the reviews by Angart et al., Pharmaceuticals (Basel) 6(4): 440-468 (2013); Kanasty et al., Molecular Therapy 20(3): 513-524 (2012); Burnett et al., Biotechnol J.

6(9): 1 130-46 (2011); Judge and MacLachlan, Hum Gene Ther 19(2): 111-24 (2008).

[000433] A large variety of modifications have been developed and applied to enhance RNA stability, reduce innate immune responses, and/or achieve other benefits that can be useful in connection with the introduction of polynucleotides into human cells, as described herein; see, e.g., the reviews by Whitehead KA et al., Annual Review of Chemical and Biomolecular Engineering, 2: 77-96 (2011); Gaglione and Messere, Mini Rev Med Chem, l0(7):578-95 (2010); Chemolovskaya el al, Curr Opin Mol Ther., 12(2): 158-67 (2010); Deleavey el al, Curr Protoc Nucleic Acid Chem Chapter l6:Unit 16.3 (2009); Behlke, Oligonucleotides 18(4):305-19 (2008); Fucini et al, Nucleic Acid Ther 22(3): 205-210 (2012); Bremsen et al, Front Genet 3: 154 (2012).

[000434] As noted above, there are a number of commercial suppliers of modified RNAs, many of which have specialized in modifications designed to improve the effectiveness of siRNAs. A variety of approaches are offered based on various findings reported in the literature. For example, Dharmacon notes that replacement of a non-bridging oxygen with sulfur

(phosphorothioate, PS) has been extensively used to improve nuclease resistance of siRNAs, as reported by Kole, Nature Reviews Drug Discovery 11 : 125-140 (2012). Modifications of the 2'- position of the ribose have been reported to improve nuclease resistance of the intemucleotide phosphate bond while increasing duplex stability (Tm), which has also been shown to provide protection from immune activation. A combination of moderate PS backbone modifications with small, well-tolerated 2'-substitutions (2'-0-Methyl, 2'-Fluoro, 2'-Hydro) have been associated with highly stable siRNAs for applications in vivo, as reported by Soutschek et al. Nature 432: 173-178 (2004); and 2'-0-Methyl modifications have been reported to be effective in improving stability as reported by Volkov, Oligonucleotides 19: 191-202 (2009). With respect to decreasing the induction of innate immune responses, modifying specific sequences with 2'-0- Methyl, 2'-Fluoro, 2'-Hydro have been reported to reduce TFR7/TFR8 interaction while generally preserving silencing activity; see, e.g., Judge et al., Mol. Ther. 13:494-505 (2006); and Cekaite et al., J. Mol. Biol. 365:90-108 (2007). Additional modifications, such as 2-thiouracil, pseudouracil, 5-methylcytosine, 5-methyluracil, and N6-methyladenosine have also been shown to minimize the immune effects mediated by TFR3, TFR7, and TFR8; see, e.g., Kariko, K. et al, Immunity 23: 165-175 (2005).

[000435] As is also known in the art, and commercially available, a number of conjugates can be applied to polynucleotides, such as RNAs, for use herein that can enhance their delivery and/or uptake by cells, including for example, cholesterol, tocopherol and folic acid, lipids, peptides, polymers, linkers and aptamers; see, e.g., the review by Winkler, Ther. Deliv. 4:791- 809 (2013).

[000436] Codon-Optimization

[000437] A polynucleotide encoding a site -directed polypeptide can be codon-optimized according to methods standard in the art for expression in the cell containing the target DNA of interest. For example, if the intended target nucleic acid is in a human cell, a human codon- optimized polynucleotide encoding Cas9 is contemplated for use for producing the Cas9 polypeptide.

[000438] Nucleic Acids Encoding System Components

[000439] The present disclosure provides a nucleic acid comprising a nucleotide sequence encoding a genome -targeting nucleic acid of the disclosure, a site-directed polypeptide of the disclosure, and/or any nucleic acid or proteinaceous molecule necessary to carry out the aspects of the methods of the disclosure.

[000440] The nucleic acid encoding a genome-targeting nucleic acid of the disclosure, a site- directed polypeptide of the disclosure, and/or any nucleic acid or proteinaceous molecule necessary to carry out the aspects of the methods of the disclosure can comprise a vector (e.g., a recombinant expression vector).

[000441] The term "vector" refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a "plasmid", which refers to a circular double-stranded DNA loop into which additional nucleic acid segments can be ligated. Another type of vector is a viral vector; wherein additional nucleic acid segments can be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) are integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome.

[000442] In some examples, vectors can be capable of directing the expression of nucleic acids to which they are operatively linked. Such vectors are referred to herein as "recombinant expression vectors", or more simply "expression vectors", which serve equivalent functions.

[000443] The term "operably linked" means that the nucleotide sequence of interest is linked to regulatory sequence (s) in a manner that allows for expression of the nucleotide sequence. The term "regulatory sequence" is intended to include, for example, promoters, enhancers and other expression control elements (e.g., polyadenylation signals). Such regulatory sequences are well known in the art and are described, for example, in Goeddel; Gene Expression Technology: Methods in Enzymology 185, Academic Press, San Diego, CA (1990). Regulatory sequences include those that direct constitutive expression of a nucleotide sequence in many types of host cells, and those that direct expression of the nucleotide sequence only in certain host cells (e.g., tissue-specific regulatory sequences). It will be appreciated by those skilled in the art that the design of the expression vector can depend on such factors as the choice of the target cell, the level of expression desired, and the like.

[000444] Expression vectors contemplated include, but are not limited to, viral vectors based on vaccinia virus, poliovirus, adenovirus, adeno-associated virus, SV40, herpes simplex virus, human immunodeficiency virus, retrovirus (e.g., Murine Leukemia Virus, spleen necrosis virus, and vectors derived from retroviruses such as Rous Sarcoma Virus, Harvey Sarcoma Virus, avian leukosis virus, a lentivirus, human immunodeficiency virus, myeloproliferative sarcoma virus, and mammary tumor virus) and other recombinant vectors. Other vectors contemplated for eukaryotic target cells include, but are not limited to, the vectors pXTl, pSG5, pSVK3, pBPV, pMSG, and pSVLSV40 (Pharmacia). Additional vectors contemplated for eukaryotic target cells include, but are not limited to, the vectors pCTx-l, pCTx-2, and pCTx-3. Other vectors can be used so long as they are compatible with the host cell.

[000445] In some examples, a vector can comprise one or more transcription and/or translation control elements. Depending on the host/vector system utilized, any of a number of suitable transcription and translation control elements, including constitutive and inducible promoters, transcription enhancer elements, transcription terminators, etc. can be used in the expression vector. The vector can be a self-inactivating vector that either inactivates the viral sequences or the components of the CRISPR machinery or other elements.

[000446] Non-limiting examples of suitable eukaryotic promoters (i.e., promoters functional in a eukaryotic cell) include those from cytomegalovirus (CMV) immediate early, herpes simplex virus (HSV) thymidine kinase, early and late SV40, long terminal repeats (LTRs) from retrovirus, human elongation factor- 1 promoter (EF1), a hybrid construct comprising the cytomegalovirus (CMV) enhancer fused to the chicken beta-actin promoter (CAG), murine stem cell virus promoter (MSCV), phosphogly cerate kinase- 1 locus promoter (PGK), and mouse metallothionein-I .

[000447] For expressing small RNAs, including guide RNAs used in connection with Cas endonuclease, various promoters such as RNA polymerase III promoters, including for example U6 and Hl, can be advantageous. Descriptions of and parameters for enhancing the use of such promoters are known in art, and additional information and approaches are regularly being described; see, e.g., Ma, H. et al, Molecular Therapy - Nucleic Acids 3, e 161 (2014) doi: 10. l038/mtna.20l4.12.

[000448] The expression vector can also contain a ribosome binding site for translation initiation and a transcription terminator. The expression vector can also comprise appropriate sequences for amplifying expression. The expression vector can also include nucleotide sequences encoding non-native tags (e.g., histidine tag, hemagglutinin tag, green fluorescent protein, etc.) that are fused to the site-directed polypeptide, thus resulting in a fusion protein.

[000449] A promoter can be an inducible promoter (e.g., a heat shock promoter, tetracycline- regulated promoter, steroid-regulated promoter, metal-regulated promoter, estrogen receptor- regulated promoter, etc.). The promoter can be a constitutive promoter (e.g., CMV promoter, UBC promoter). In some cases, the promoter can be a spatially restricted and/or temporally restricted promoter (e.g., a tissue specific promoter, a cell type specific promoter, etc.).

[000450] The nucleic acid encoding a genome-targeting nucleic acid of the disclosure and/or a site-directed polypeptide can be packaged into or on the surface of delivery vehicles for delivery to cells. Delivery vehicles contemplated include, but are not limited to, nanospheres, liposomes, quantum dots, nanoparticles, polyethylene glycol particles, hydrogels, and micelles. As described in the art, a variety of targeting moieties can be used to enhance the preferential interaction of such vehicles with desired cell types or locations.

[000451] Introduction of the complexes, polypeptides, and nucleic acids of the disclosure into cells can occur by viral or bacteriophage infection, transfection, conjugation, protoplast fusion, lipofection, electroporation, nucleofection, calcium phosphate precipitation, polyethyleneimine (PEI)-mediated transfection, DEAE-dextran mediated transfection, liposome-mediated transfection, particle gun technology, calcium phosphate precipitation, direct micro-injection, nanoparticle-mediated nucleic acid delivery, and the like.

[000452] microRNAs (miRNAs)

[000453] Another class of gene regulatory regions is microRNA (miRNA) binding sites.

miRNAs are non-coding RNAs that play key roles in post-transcriptional gene regulation.

miRNAs can regulate the expression of 30% of all mammalian protein-encoding genes. Specific and potent gene silencing by double stranded RNA (RNAi) was discovered, plus additional small noncoding RNA (Canver, M.C. el al, Nature (2015)). The largest class of non-coding RNAs important for gene silencing is miRNAs. In mammals, miRNAs are first transcribed as long RNA transcripts, which can be separate transcriptional units, part of protein introns, or other transcripts. The long transcripts are called primary miRNA (pri -miRNA) that include imperfectly base-paired hairpin structures. These pri-miRNA can be cleaved into one or more shorter precursor miRNAs (pre-miRNAs) by Microprocessor, a protein complex in the nucleus, involving Drosha. [000454] Pre-miRNAs are short stem loops ~70 nucleotides in length with a 2-nucleotide 3’- overhang that are exported into the mature 19-25 nucleotide miRNA:miRNA* duplexes. The miRNA strand with lower base pairing stability (the guide strand) can be loaded onto the RNA- induced silencing complex (RISC). The passenger guide strand (marked with *), can be functional, but is usually degraded. The mature miRNA tethers RISC to partly complementary sequence motifs in target mRNAs predominantly found within the 3' untranslated regions (UTRs) and induces posttranscriptional gene silencing (Bartel, D.P. Cell 136, 215-233 (2009); Saj, A. & Lai, E.C. Curr Opin Genet Dev il, 504-510 (2011)).

[000455] miRNAs can be important in development, differentiation, cell cycle and growth control, and in virtually all biological pathways in mammals and other multicellular organisms. miRNAs can also be involved in cell cycle control, apoptosis and stem cell differentiation, hematopoiesis, hypoxia, muscle development, neurogenesis, insulin secretion, cholesterol metabolism, aging, viral replication and immune responses.

[000456] A single miRNA can target hundreds of different mRNA transcripts, while an individual transcript can be targeted by many different miRNAs. More than 28645 miRNAs have been annotated in the latest release of miRBase (v.2l). Some miRNAs can be encoded by multiple loci, some of which can be expressed from tandemly co-transcribed clusters. The features allow for complex regulatory networks with multiple pathways and feedback controls. miRNAs can be integral parts of these feedback and regulatory circuits and can help regulate gene expression by keeping protein production within limits (Herranz, H. & Cohen, S.M. Genes Dev 24, 1339-1344 (2010); Posadas, D.M. & Carthew, R.W. Curr Opin Genet Dev 27, 1-6 (2014)).

[000457] miRNAs can also be important in a large number of human diseases that are associated with abnormal miRNA expression. This association underscores the importance of the miRNA regulatory pathway. Recent miRNA deletion studies have linked miRNAs with regulation of the immune responses (Stem-Ginossar, N. et al., Science 317, 376-381 (2007)).

[000458] miRNAs also have a strong link to cancer and can play a role in different types of cancer. miRNAs have been found to be downregulated in a number of tumors. miRNAs can be important in the regulation of key cancer-related pathways, such as cell cycle control and the DNA damage response, and can therefore be used in diagnosis and can be targeted clinically. miRNAs can delicately regulate the balance of angiogenesis, such that experiments depleting all miRNAs suppress tumor angiogenesis (Chen, S. et al., Genes Dev 28, 1054-1067 (2014)). [000459] As has been shown for protein coding genes, miRNA genes can also be subject to epigenetic changes occurring with cancer. Many miRNA loci can be associated with CpG islands increasing their opportunity for regulation by DNA methylation (Weber, B., Stresemann, C., Brueckner, B. & Lyko, F. Cell Cycle 6, 1001-1005 (2007)). The majority of studies have used treatment with chromatin remodeling drugs to reveal epigenetically silenced miRNAs.

[000460] In addition to their role in RNA silencing, miRNAs can also activate translation (Posadas, D.M. & Carthew, R.W. Curr Opin Genet Dev 27, 1-6 (2014)). Knocking out these sites can lead to decreased expression of the targeted gene, while introducing these sites can increase expression.

[000461] Individual miRNAs can be knocked out most effectively by mutating the seed sequence (bases 2-8 of the miRNA), which can be important for binding specificity. Cleavage in this region, followed by mis-repair by NHEJ can effectively abolish miRNA function by blocking binding to target sites. miRNAs could also be inhibited by specific targeting of the special loop region adjacent to the palindromic sequence. Catalytically inactive Cas9 can also be used to inhibit shRNA expression (Zhao, Y. el al., Sci Rep 4, 3943 (2014)). In addition to targeting the miRNAs, the binding sites can also be targeted and mutated to prevent the silencing by miRNAs.

[000462] According to the present disclosure, any of the miRNAs or their binding sites can be incorporated into the compositions of the invention.

[000463] The compositions can have a region such as, but not limited to, a region comprising the sequence of any of the miRNAs listed in SEQ ID NOs: 613-4696, the reverse complement of the miRNAs listed in SEQ ID NOs: 613-4696, or the miRNA anti-seed region of any of the miRNAs listed in SEQ ID NOs: 613-4696.

[000464] The compositions of the invention can comprise one or more miRNA target sequences, miRNA sequences, or miRNA seeds. Such sequences can correspond to any known miRNA such as those taught in US Publication No. 2005/0261218 and US Publication No. 2005/0059005. As a non-limiting example, known miRNAs, their sequences, and their binding site sequences in the human genome are listed in SEQ ID NOs: 613-4696.

[000465] A miRNA sequence comprises a“seed” region, i.e., a sequence in the region of positions 2-8 of the mature miRNA, which sequence has perfect Watson-Crick complementarity to the miRNA target sequence. A miRNA seed can comprise positions 2-8 or 2-7 of the mature miRNA. In some examples, a miRNA seed can comprise 7 nucleotides (e.g., nucleotides 2-8 of the mature miRNA), wherein the seed-complementary site in the corresponding miRNA target is flanked by an adenine (A) opposed to miRNA position 1. In some examples, a miRNA seed can comprise 6 nucleotides (e.g., nucleotides 2-7 of the mature miRNA), wherein the seed complementary site in the corresponding miRNA target is flanked by an adenine (A) opposed to miRNA position 1. See for example, Grimson A, Farh KK, Johnston WK, Garrett-Engele P, Lim LP, Bartel DP; Mol Cell. 2007 Jul 6;27(l):91-105. The bases of the miRNA seed have complete complementarity with the target sequence.

[000466] Identification of miRNAs, miRNA target regions, and their expression patterns and role in biology have been reported (Bonauer et ak, Curr Drug Targets 2010 11 :943-949; Anand and Cheresh Curr Opin Hematol 2011 18: 171-176; Contreras and Rao Leukemia 2012 26:404- 413 (2011 Dec 20. doi: l0T038/leu.20l l .356); Bartel Cell 2009 136:215-233; Landgraf et al, Cell, 2007 129: 1401-1414; Gentner and Naldini, Tissue Antigens. 2012 80:393-403.

[000467] For example, if the composition is not intended to be delivered to the liver but ends up there, then miR-l22, a miRNA abundant in liver, can inhibit the expression of the sequence delivered if one or multiple target sites of miR-l22 are engineered into the polynucleotide encoding that target sequence. Introduction of one or multiple binding sites for different miRNAs can be engineered to further decrease the longevity, stability, and protein translation hence providing an additional layer of tenability.

[000468] As used herein, the term“miRNA site” refers to a miRNA target site or a miRNA recognition site, or any nucleotide sequence to which a miRNA binds or associates. It should be understood that“binding” can follow traditional Watson-Crick hybridization rules or can reflect any stable association of the miRNA with the target sequence at or adjacent to the miRNA site.

[000469] Conversely, for the purposes of the compositions of the present disclosure, miRNA binding sites can be engineered out of (i.e. removed from) sequences in which they naturally occur in order to increase protein expression in specific tissues. For example, miR-l22 binding sites can be removed to improve protein expression in the liver.

[000470] Specifically, miRNAs are known to be differentially expressed in immune cells (also called hematopoietic cells), such as antigen presenting cells (APCs) (e.g. dendritic cells and macrophages), macrophages, monocytes, B lymphocytes, T lymphocytes, granulocytes, natural killer cells, etc. Immune cell specific miRNAs are involved in immunogenicity, autoimmunity, the immune -response to infection, inflammation, as well as unwanted immune response after gene therapy and tissue/organ transplantation. Immune cells specific miRNAs also regulate many aspects of development, proliferation, differentiation and apoptosis of hematopoietic cells (immune cells). For example, miR-l42 and miR-l46 are exclusively expressed in the immune cells, particularly abundant in myeloid dendritic cells. Introducing the miR-l42 binding site into the 3’-UTR of a polypeptide of the present disclosure can selectively suppress the gene expression in the antigen presenting cells through miR-l42 mediated mRNA degradation, limiting antigen presentation in professional APCs (e.g. dendritic cells) and thereby preventing antigen-mediated immune response after gene delivery (see, Annoni A et al., blood, 2009, 114, 5152-5161.

[000471] In one example, miRNA binding sites that are known to be expressed in immune cells, in particular, the antigen presenting cells, can be engineered into the polynucleotides to suppress the expression of the polynucleotide in APCs through miRNA mediated RNA degradation, subduing the antigen-mediated immune response, while the expression of the polynucleotide is maintained in non-immune cells where the immune cell specific miRNAs are not expressed.

[000472] Many miRNA expression studies have been conducted, and are described in the art, to profile the differential expression of miRNAs in various cancer cells /tissues and other diseases. Some miRNAs are abnormally over-expressed in certain cancer cells and others are under-expressed. For example, miRNAs are differentially expressed in cancer cells

(W02008/154098, US2013/0059015, US2013/0042333, WO2011/157294); cancer stem cells (US2012/0053224); pancreatic cancers and diseases (US2009/0131348, US2011/0171646, US2010/0286232, US8389210); asthma and inflammation (US8415096); prostate cancer (US2013/0053264); hepatocellular carcinoma (WO2012/151212, US2012/0329672,

W02008/054828, US8252538); lung cancer cells (WO2011/076143, W02013/033640, W02009/070653, US2010/0323357); cutaneous T-cell lymphoma (W02013/011378); colorectal cancer cells (WO2011/0281756, WO2011/076142); cancer positive lymph nodes

(W02009/100430, US2009/0263803); nasopharyngeal carcinoma (EP2112235); chronic obstructive pulmonary disease (US2012/0264626, US2013/0053263); thyroid cancer

(WO2013/066678); ovarian cancer cells ( US2012/0309645, WO2011/095623); breast cancer cells (W02008/154098, W02007/081740, US2012/0214699), leukemia and lymphoma

(W02008/073915, US2009/0092974, US2012/0316081, US2012/0283310, W02010/018563.

[000473] Human Cells

[000474] For ameliorating autosomal dominant CORD or any disorder associated with GUCY2D, as described and illustrated herein, the principal targets for gene editing are human cells. For example, in the ex vivo methods, the human cells can be somatic cells, which after being modified using the techniques as described, can give rise to differentiated cells, e.g., photoreceptor cells or retinal progenitor cells. For example, in the in vivo methods, the human cells can be photoreceptor cells or retinal progenitor cells.

[000475] By performing gene editing in autologous cells that are derived from and therefore already completely matched with the patient in need, it is possible to generate cells that can be safely re-introduced into the patient, and effectively give rise to a population of cells that can be effective in ameliorating one or more clinical conditions associated with the patient's disease.

[000476] Progenitor cells (also referred to as stem cells herein) are capable of both proliferation and giving rise to more progenitor cells, these in turn having the ability to generate a large number of mother cells that can in turn give rise to differentiated or differentiable daughter cells. The daughter cells themselves can be induced to proliferate and produce progeny that subsequently differentiate into one or more mature cell types, while also retaining one or more cells with parental developmental potential. The term "stem cell" refers then, to a cell with the capacity or potential, under particular circumstances, to differentiate to a more specialized or differentiated phenotype, and which retains the capacity, under certain circumstances, to proliferate without substantially differentiating. In one aspect, the term progenitor or stem cell refers to a generalized mother cell whose descendants (progeny) specialize, often in different directions, by differentiation, e.g., by acquiring completely individual characters, as occurs in progressive diversification of embryonic cells and tissues. Cellular differentiation is a complex process typically occurring through many cell divisions. A differentiated cell can derive from a multipotent cell that itself is derived from a multipotent cell, and so on. While each of these multipotent cells can be considered stem cells, the range of cell types that each can give rise to can vary considerably. Some differentiated cells also have the capacity to give rise to cells of greater developmental potential. Such capacity can be natural or can be induced artificially upon treatment with various factors. In many biological instances, stem cells can also be

"multipotent" because they can produce progeny of more than one distinct cell type, but this is not required for "stem-ness."

[000477] Self-renewal can be another important aspect of the stem cell. In theory, self-renewal can occur by either of two major mechanisms. Stem cells can divide asymmetrically, with one daughter retaining the stem state and the other daughter expressing some distinct other specific function and phenotype. Alternatively, some of the stem cells in a population can divide symmetrically into two stems, thus maintaining some stem cells in the population as a whole, while other cells in the population give rise to differentiated progeny only. Generally,

"progenitor cells" have a cellular phenotype that is more primitive (i.e.. is at an earlier step along a developmental pathway or progression than is a fully differentiated cell). Often, progenitor cells also have significant or very high proliferative potential. Progenitor cells can give rise to multiple distinct differentiated cell types or to a single differentiated cell type, depending on the developmental pathway and on the environment in which the cells develop and differentiate.

[000478] In the context of cell ontogeny, the adjective "differentiated," or "differentiating" is a relative term. A "differentiated cell" is a cell that has progressed further down the developmental pathway than the cell to which it is being compared. Thus, stem cells can differentiate into lineage-restricted precursor cells (such as a myocyte progenitor cell), which in turn can differentiate into other types of precursor cells further down the pathway (such as a myocyte precursor), and then to an end-stage differentiated cell, which plays a characteristic role in a certain tissue type, and can or cannot retain the capacity to proliferate further.

[000479] Edited Human cells

[000480] Provided herein are methods for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell. Provided herein are gRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell.

[000481] These methods and/or gRNAs disclosed herein can be used to edit a population of human cells. A sufficient number of human cells within a cell population can be edited and used to treat a patient. For example, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, or 50% of the human cells within a cell population can be edited and used to treat a patient. In other examples, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 1%, or 0.5% of the human cells within a cell population can be edited and used to treat a patient. In various examples, the edited human cells can be first selected and cultured to expand the number of edited cells before administering them to a patient.

[000482] Induced Pluripotent Stem Cells

[000483] The genetically engineered human cells described herein can be induced pluripotent stem cells (iPSCs). An advantage of using iPSCs is that the cells can be derived from the same subject to which the progenitor cells are to be administered. That is, a somatic cell can be obtained from a subject, reprogrammed to an induced pluripotent stem cell, and then re- differentiated into a progenitor cell to be administered to the subject (e.g., autologous cells). Because the progenitors are essentially derived from an autologous source, the risk of engraftment rejection or allergic response can be reduced compared to the use of cells from another subject or group of subjects. In addition, the use of iPSCs negates the need for cells obtained from an embryonic source. Thus, in one aspect, the stem cells used in the disclosed methods are not embryonic stem cells.

[000484] Although differentiation is generally irreversible under physiological contexts, several methods have been recently developed to reprogram somatic cells to iPSCs. Exemplary methods are known to those of skill in the art and are described briefly herein below.

[000485] The term "reprogramming" refers to a process that alters or reverses the

differentiation state of a differentiated cell (e.g., a somatic cell). Stated another way, reprogramming refers to a process of driving the differentiation of a cell backwards to a more undifferentiated or more primitive type of cell. It should be noted that placing many primary cells in culture can lead to some loss of fully differentiated characteristics. Thus, simply culturing such cells included in the term differentiated cells does not render these cells non- differentiated cells (e.g., undifferentiated cells) or pluripotent cells. The transition of a differentiated cell to pluripotency requires a reprogramming stimulus beyond the stimuli that lead to partial loss of differentiated character in culture. Reprogrammed cells also have the characteristic of the capacity of extended passaging without loss of growth potential, relative to primary cell parents, which generally have capacity for only a limited number of divisions in culture.

[000486] The cell to be reprogrammed can be either partially or terminally differentiated prior to reprogramming. Reprogramming can encompasse complete reversion of the differentiation state of a differentiated cell (e.g., a somatic cell) to a pluripotent state or a multipotent state. Reprogramming can encompasse complete or partial reversion of the differentiation state of a differentiated cell (e.g., a somatic cell) to an undifferentiated cell (e.g., an embryonic-like cell). Reprogramming can result in expression of particular genes by the cells, the expression of which further contributes to reprogramming. In certain examples described herein, reprogramming of a differentiated cell (e.g., a somatic cell) can cause the differentiated cell to assume an

undifferentiated state (e.g., is an undifferentiated cell). The resulting cells are referred to as "reprogrammed cells," or "induced pluripotent stem cells (iPSCs or iPS cells)."

[000487] Reprogramming can involve alteration, e.g., reversal, of at least some of the heritable patterns of nucleic acid modification (e.g., methylation), chromatin condensation, epigenetic changes, genomic imprinting, etc., that occur during cellular differentiation. Reprogramming is distinct from simply maintaining the existing undifferentiated state of a cell that is already pluripotent or maintaining the existing less than fully differentiated state of a cell that is already a multipotent cell (e.g., a myogenic stem cell). Reprogramming is also distinct from promoting the self-renewal or proliferation of cells that are already pluripotent or multipotent, although the compositions and methods described herein can also be of use for such purposes, in some examples.

[000488] Many methods are known in the art that can be used to generate pluripotent stem cells from somatic cells. Any such method that reprograms a somatic cell to the pluripotent phenotype would be appropriate for use in the methods described herein.

[000489] Reprogramming methodologies for generating pluripotent cells using defined combinations of transcription factors have been described. Mouse somatic cells can be converted to ES cell-like cells with expanded developmental potential by the direct transduction of Oct4, Sox2, Klf4, and c-Myc; see, e.g., Takahashi and Yamanaka, Cell 126(4): 663-76 (2006). iPSCs resemble ES cells, as they restore the pluripotency-associated transcriptional circuitry and much of the epigenetic landscape. In addition, mouse iPSCs satisfy all the standard assays for pluripotency: specifically, in vitro differentiation into cell types of the three germ layers, teratoma formation, contribution to chimeras, germline transmission [see, e.g., Maherali and Hochedlinger, Cell Stem Cell. 3(6):595-605 (2008)], and tetraploid complementation.

[000490] Human iPSCs can be obtained using similar transduction methods, and the transcription factor trio, OCT4, SOX2, and NANOG, has been established as the core set of transcription factors that govern pluripotency; see, e.g., Budniatzky and Gepstein, Stem Cells Transl Med. 3(4):448-57 (2014); Barrett et al., Stem Cells Trans Med 3: 1-6 sctm.2014-0121 (2014); Focosi et al., Blood Cancer Journal 4: e2l 1 (2014). The production of iPSCs can be achieved by the introduction of nucleic acid sequences encoding stem cell-associated genes into an adult, somatic cell, historically using viral vectors.

[000491] iPSCs can be generated or derived from terminally differentiated somatic cells, as well as from adult stem cells, or somatic stem cells. That is, a non-pluripotent progenitor cell can be rendered pluripotent or multipotent by reprogramming. In such instances, it cannot be necessary to include as many reprogramming factors as required to reprogram a terminally differentiated cell. Further, reprogramming can be induced by the non-viral introduction of reprogramming factors, e.g., by introducing the proteins themselves, or by introducing nucleic acids that encode the reprogramming factors, or by introducing messenger RNAs that upon translation produce the reprogramming factors (see e.g., Warren et al., Cell Stem Cell, 7(5):6l8- 30 (2010). Reprogramming can be achieved by introducing a combination of nucleic acids encoding stem cell-associated genes, including, for example, Oct-4 (also known as Oct-3/4 or Pouf5 l), Soxl, Sox2, Sox3, Sox 15, Sox 18, NANOG, Klfl, Klf2, Klf4, Klf5, NR5A2, c-Myc, 1- Myc, n-Myc, Rem2, Tert, and LIN28. Reprogramming using the methods and compositions described herein can further comprise introducing one or more of Oct-3/4, a member of the Sox family, a member of the Klf family, and a member of the Myc family to a somatic cell. The methods and compositions described herein can further comprise introducing one or more of each of Oct-4, Sox2, Nanog, c-MYC and Klf4 for reprogramming. As noted above, the exact method used for reprogramming is not necessarily critical to the methods and compositions described herein. However, where cells differentiated from the reprogrammed cells are to be used in, e.g., human therapy, in one aspect the reprogramming is not effected by a method that alters the genome. Thus, in such examples, reprogramming can be achieved, e.g., without the use of viral or plasmid vectors.

[000492] The efficiency of reprogramming (i.e.. the number of reprogrammed cells) derived from a population of starting cells can be enhanced by the addition of various agents, e.g., small molecules, as shown by Shi et al., Cell-Stem Cell 2:525-528 (2008); Huangfu et al., Nature Biotechnology 26(7):795-797 (2008) and Marson et al., Cell-Stem Cell 3: 132-135 (2008).

Thus, an agent or combination of agents that enhance the efficiency or rate of induced pluripotent stem cell production can be used in the production of patient-specific or disease- specific iPSCs. Some non-limiting examples of agents that enhance reprogramming efficiency include soluble Wnt, Wnt conditioned media, BIX-01294 (a G9a histone methyltransferase), PD0325901 (a MEK inhibitor), DNA methyltransferase inhibitors, histone deacetylase (HDAC) inhibitors, valproic acid, 5'-azacytidine, dexamethasone, suberoylanilide, hydroxamic acid (SAHA), vitamin C, and trichostatin (TSA), among others.

[000493] Other non-limiting examples of reprogramming enhancing agents include:

Suberoylanilide Hydroxamic Acid (SAHA (e.g., MK0683, vorinostat) and other hydroxamic acids), BML-210, Depudecin (e.g., (-)-Depudecin), HC Toxin, Nullscript (4-(l,3-Dioxo-lH,3H- benzo[de]isoquinolin-2-yl)-N-hydroxybutanamide), Phenylbutyrate (e.g., sodium

phenylbutyrate) and Valproic Acid ((VP A) and other short chain fatty acids), Scriptaid, Suramin Sodium, Trichostatin A (TSA), APHA Compound 8, Apicidin, Sodium Butyrate,

pivaloyloxymethyl butyrate (Pivanex, AN-9), Trapoxin B, Chlamydocin, Depsipeptide (also known as FR901228 or FK228), benzamides (e.g., CI-994 (e.g., N-acetyl dinaline) and MS-27- 275), MGCD0103, NVP-FAQ-824, CBHA (m-carboxycinnaminic acid bishydroxamic acid), JNJ16241199, Tubacin, A-161906, proxamide, oxamflatin, 3-C1-UCHA (e.g., 6-(3- chlorophenylureido)caproic hydroxamic acid), AOE (2-amino-8-oxo-9, lO-epoxydecanoic acid), CHAP31 and CHAP 50. Other reprogramming enhancing agents include, for example, dominant negative forms of the HDACs (e.g., catalytically inactive forms), siRNA inhibitors of the HDACs, and antibodies that specifically bind to the HDACs. Such inhibitors are available, e.g., from BIOMOL International, Fukasawa, Merck Biosciences, Novartis, Gloucester

Pharmaceuticals, Titan Pharmaceuticals, MethylGene, and Sigma Aldrich.

[000494] To confirm the induction of pluripotent stem cells for use with the methods described herein, isolated clones can be tested for the expression of a stem cell marker. Such expression in a cell derived from a somatic cell identifies the cells as induced pluripotent stem cells. Stem cell markers can be selected from the non-limiting group including SSEA3, SSEA4, CD9, Nanog, Fbxl5, Ecatl, Esgl, Eras, Gdf3, Fgf4, Cripto, Daxl, Zpf296, Slc2a3, Rexl, Utfl, and Natl. In one case, for example, a cell that expresses Oct4 or Nanog is identified as pluripotent. Methods for detecting the expression of such markers can include, for example, RT-PCR and immunological methods that detect the presence of the encoded polypeptides, such as Western blots or flow cytometric analyses. Detection can involve not only RT-PCR, but can also include detection of protein markers. Intracellular markers can be best identified via RT-PCR, or protein detection methods such as immunocytochemistry, while cell surface markers are readily identified, e.g., by immunocytochemistry .

[000495] The pluripotent stem cell character of isolated cells can be confirmed by tests evaluating the ability of the iPSCs to differentiate into cells of each of the three germ layers. As one example, teratoma formation in nude mice can be used to evaluate the pluripotent character of the isolated clones. The cells can be introduced into nude mice and histology and/or immunohistochemistry can be performed on a tumor arising from the cells. The growth of a tumor comprising cells from all three germ layers, for example, further indicates that the cells are pluripotent stem cells.

[000496] Retinal progenitor cells and Photoreceptor cells

[000497] In some examples, the genetically engineered human cells described herein are photoreceptor cells or retinal progenitor cells (RPCs). RPCs are multipotent progenitor cells that can give rise to all six neurons of the retina as well as the Miiller glia. Miiller glia are a type of retinal glial cells and are the major glial component of the retina. Their function is to support the neurons of the retina and to maintain retinal homeostasis and integrity. Miiller glia isolated from adult human retinas have been shown to differentiate into rod photoreceptors. Functional characterization of such Miiller glia-derived photoreceptors by patch-clamp recordings has revealed that their electrical properties are comparable to those of adult rods (Giannelli et ak, 2011, Stem Cells, (2):344-56). RPCs are gradually specified into lineage-restricted precursor cells during retinogenesis, which then maturate into the terminally differentiated neurons or Miiuller glia. Fetal-derived human retinal progenitor cells (hRPCs) exhibit molecular characteristics indicative of a retinal progenitor state up to the sixth passage. They demonstrate a gradual decrease in the percentages of KI67-, SOX2-, and vimentin-positive cells from passages 1 to 6, whereas a sustained expression of nestin and PAX6 is seen through passage 6.

Microarray analysis of passage 1 hRPCs demonstrates the expression of early retinal developmental genes: VIM (vimentin), KI67, NES (nestin), PAX6, SOX2, HES5, GNL3, OTX2, DACH1, SIX6, and CHX10 (VSX2). The hRPCs are functional in nature and respond to excitatory neurotransmitters (Schmitt et al., 2009, Investigative Ophthalmology and Visual Sciences. 2009;50(l2):590l-8). The outermost region of the retina contains a supportive retinal pigment epithelium (RPE) layer, which maintains photoreceptor health by transporting nutrients and recycling shed photoreceptor parts. The RPE is attached to Bruch's membrane, an extracellular matrix structure at the interface between the choroid and retina. On the other side of the RPE, moving inwards towards the interior of the eye, there are three layers of neurons: lightsensing rod and cone photoreceptors, a middle layer of connecting neurons (amacrine, bipolar and horizontal cells) and the innermost layer of ganglion cells, which transmit signals originating in the photoreceptor layer through the optic nerve and into the brain. In some aspects, the genetically engineered human cells described herein are photoreceptor cells, which are specialized types of neurons found in the retina. Photoreceptors convert light into signals that are able to stimulate biological processes and are responsible for sight. Rods and cones are the two classic photoreceptor cells that contribute information to the visual system.

[000498] Isolating a Retinal Progenitor Cell and Photoreceptor Cell

[000499] Retinal cells, including progenitor cells may be isolated according to any method known in the art. For example, human retinal cells are isolated from fresh surgical specimens. The retinal pigment epithelium (RPE) is separated from the choroid by digesting the tissue with type IV collagenase and the retinal pigment epithelium patches are cultured. Following the growth of 100-500 cells from the explant, the primary cultures are passaged (Ishida M. et al., Current Eye Research 1998; 17(4): 392-402) and characterized for expression of RPE markers. Rods are isolated by disruption of the biopsied retina using papain. Precautions are taken to avoid a harsh disruption and improve cell yield. The isolated cells are sorted to yield a population of pure rod cells and characterized further by immunostaining (Feodorova et al., MethodsX 2015; 2:39-46). [000500] In order to isolate cones, neural retina is identified, cut-out, and placed on 10% gelatin. The inner retinal layers are isolated using a laser. The isolated cone monolayers are cultured for 18 hours and compared with untreated retinas by light microscopy and transmission microscopy to check for any structural damage. The cells are characterized for expression of cone-specific markers (Salchow et ak, Current Eye Research 200l;22).

[000501] In order to isolate retinal progenitor cells, the biopsied retina is minced with dual scalpels and digested enzymatically in an incubator at 37°C. The supernatants of the digested cells are centrifuged and the cells are resuspended in cell-free retinal progenitor-conditioned medium. The cells are transferred to fibronectin-coated tissue culture flasks containing fresh media and cultured (Klassen et ak, Jomal of Neuroscience Research 2004; 77:334-343).

[000502] Creating patient specific iPSCs

[000503] One step of the ex vivo methods of the present disclosure can involve creating a patient-specific iPS cell, patient-specific iPS cells, or a patient specific iPS cell line. There are many established methods in the art for creating patient specific iPS cells, as described in Takahashi and Yamanaka 2006; Takahashi, Tanabe et al. 2007. For example, the creating step can comprise: a) isolating a somatic cell, such as a skin cell or fibroblast, from the patient; and b) introducing a set of pluripotency -associated genes into the somatic cell in order to induce the cell to become a pluripotent stem cell. The set of pluripotency-associated genes can be one or more of the genes selected from the group consisting of OCT4, SOX1, SOX2, SOX3, SOX15, SOX18, NANOG, KLF1, KFF2, KFF4, KFF5, c-MYC, n-MYC, REM2, TERT and FIN28.

[000504] Performing a biopsy or aspirate of the patient’s bone marrow

[000505] A biopsy or aspirate is a sample of tissue or fluid taken from the body. There are many different kinds of biopsies or aspirates. Nearly all of them involve using a sharp tool to remove a small amount of tissue. If the biopsy will be on the skin or other sensitive area, numbing medicine can be applied first. A biopsy or aspirate can be performed according to any of the known methods in the art. For example, in a bone marrow aspirate, a large needle is used to enter the pelvis bone to collect bone marrow.

[000506] Isolating a mesenchymal stem cell

[000507] Mesenchymal stem cells can be isolated according to any method known in the art, such as from a patient’s bone marrow or peripheral blood. For example, marrow aspirate can be collected into a syringe with heparin. Cells can be washed and centrifuged on a Percoll™ density gradient. Cells, such as blood cells, liver cells, interstitial cells, macrophages, mast cells, and thymocytes, can be separated using density gradient centrifugation media, Percoll™. The cells can then be cultured in Dulbecco's modified Eagle's medium (DMEM) (low glucose) containing 10% fetal bovine serum (FBS) (Pittinger MF, Mackay AM, Beck SC et al., Science 1999; 284: 143-147).

[000508] Differentiation of genome-edited iPSCs into other cell types

[000509] Another step of the ex vivo methods of the present disclosure can comprise differentiating the genome-edited iPSCs into photoreceptor cells. The differentiating step may be performed according to any method known in the art. For example, iPSCs can be used to generate retinal organioids and photoreceptors as decribed in the art (Phillips et ah, Stem Cells, June 2014, 32(6): pgs. 1480-1492; Zhong et al. Nat. Commun., 2014, 5: pg 4047; Tucker et ak, PFoS One, April 2011, 6(4): e l8992). For example, hiPSC are differentiated into retinal progenitor cells using various treatments, including Wnt, Nodal, and Notch pathway inhibitors (Noggin, Dkl, FeftyA, and DAPT) and other growth factors. The retinal progenitor cells are further differentiated into photoreceptor cells, the treatment including: exposure to native retinal cells in coculture systems, RX+ or Mitf+ by subsequent treatment with retinoic acid and taurine, or exposure to several exogenous factors including Noggin, Dkkl, DAPT, and insulin-like growth factor (Y ang et ak, Stem Cells International 2016).

[000510] Differentiation of genome-edited mesenchymal stem cells into Photoreceptor cells or retinal progenitor cells

[000511] Another step of the ex vivo methods of the present disclosure can comprise differentiating the genome-edited mesenchymal stem cells into photoreceptor cells or retinal progenitor cells. The differentiating step can be performed according to any method known in the art.

[000512] Implanting cells into patients

[000513] Another step of the ex vivo methods of the present disclosure can comprise implanting the photoreceptor cells or retinal progenitor cells into patients. This implanting step can be accomplished using any method of implantation known in the art. For example, the genetically modified cells can be injected directly in the patient’s blood or otherwise administered to the patient.

[000514] Another step of the ex vivo methods of the invention involves implanting the photoreceptor cells or retinal progenitor cells into patients. This implanting step can be accomplished using any method of implantation known in the art. For example, the genetically modified cells can be injected directly in the patient’s eye or otherwise administered to the patient. [000515] Genetically Modified Cells

[000516] The term "genetically modified cell" refers to a cell that comprises at least one genetic modification introduced by genome editing (e.g., using the CRISPR/Cas9/Cpfl system). In some ex vivo examples herein, the genetically modified cell can be genetically modified progenitor cell. In some in vivo examples herein, the genetically modified cell can be a genetically modified photoreceptor cell or retinal progenitor cell. A genetically modified cell comprising an exogenous genome-targeting nucleic acid and/or an exogenous nucleic acid encoding a genome -targeting nucleic acid is contemplated herein.

[000517] The term "control treated population" describes a population of cells that has been treated with identical media, viral induction, nucleic acid sequences, temperature, confluency, flask size, pH, etc., with the exception of the addition of the genome editing components. Any method known in the art can be used to measure restoration of GUCY2D gene or protein expression or activity, for example Western Blot analysis of the RetGCl protein or real time PCR for quantifying GUCY2D mRNA.

[000518] The term "isolated cell" refers to a cell that has been removed from an organism in which it was originally found, or a descendant of such a cell. Optionally, the cell can be cultured in vitro, e.g. , under defined conditions or in the presence of other cells. Optionally, the cell can be later introduced into a second organism or re-introduced into the organism from which it (or the cell from which it is descended) was isolated.

[000519] The term "isolated population" with respect to an isolated population of cells refers to a population of cells that has been removed and separated from a mixed or heterogeneous population of cells. In some cases, the isolated population can be a substantially pure population of cells, as compared to the heterogeneous population from which the cells were isolated or enriched. In some cases, the isolated population can be an isolated population of human progenitor cells, e.g., a substantially pure population of human progenitor cells, as compared to a heterogeneous population of cells comprising human progenitor cells and cells from which the human progenitor cells were derived.

[000520] The term "substantially enhanced," with respect to a particular cell population, refers to a population of cells in which the occurrence of a particular type of cell is increased relative to pre-existing or reference levels, by at least 2-fold, at least 3-, at least 4-, at least 5-, at least 6-, at least 7-, at least 8-, at least 9, at least 10-, at least 20-, at least 50-, at least 100-, at least 400-, at least 1000-, at least 5000-, at least 20000-, at least 100000- or more fold depending, e.g., on the desired levels of such cells for ameliorating autosomal dominant CORD. [000521] The term "substantially enriched" with respect to a particular cell population, refers to a population of cells that is at least about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70% or more with respect to the cells making up a total cell population.

[000522] The terms "substantially pure" with respect to a particular cell population, refers to a population of cells that is at least about 75%, at least about 85%, at least about 90%, or at least about 95% pure, with respect to the cells making up a total cell population. That is, the terms "substantially pure" or "essentially purified," with regard to a population of progenitor cells, refers to a population of cells that contain fewer than about 20%, about 15%, about 10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about 3%, about 2%, about 1%, or less than 1%, of cells that are not progenitor cells as defined by the terms herein.

[000523] Delivery

[000524] Guide RNA polynucleotides (RNA or DNA) and/or endonuclease polynucleotide(s) (RNA or DNA) can be delivered by viral or non-viral delivery vehicles known in the art.

Alternatively, endonuclease polypeptide (s) can be delivered by viral or non-viral delivery vehicles known in the art, such as electroporation or lipid nanoparticles. In further alternative aspects, the DNA endonuclease can be delivered as one or more polypeptides, either alone or pre-complexed with one or more guide RNAs, or one or more crRNA together with a tracrRNA.

[000525] Polynucleotides can be delivered by non-viral delivery vehicles including, but not limited to, nanoparticles, liposomes, ribonucleoproteins, positively charged peptides, small molecule RNA-conjugates, aptamer-RNA chimeras, and RNA-fusion protein complexes. Some exemplary non-viral delivery vehicles are described in Peer and Lieberman, Gene Therapy, 18:

1127-1133 (2011) (which focuses on non-viral delivery vehicles for siRNA that are also useful for delivery of other polynucleotides).

[000526] Polynucleotides, such as guide RNA, sgRNA, and mRNA encoding an endonuclease, can be delivered to a cell or a patient by a lipid nanoparticle (LNP).

[000527] A LNP refers to any particle having a diameter of less than 1000 nm, 500 nm, 250 nm, 200 nm, 150 nm, 100 nm, 75 nm, 50 nm, or 25 nm. Alternatively, a nanoparticle can range in size from 1-1000 nm, 1-500 nm, 1-250 nm, 25-200 nm, 25-100 nm, 35-75 nm, or 25-60 nm.

[000528] LNPs can be made from cationic, anionic, or neutral lipids. Neutral lipids, such as the fusogenic phospholipid DOPE or the membrane component cholesterol, can be included in LNPs as 'helper lipids' to enhance transfection activity and nanoparticle stability. Limitations of cationic lipids include low efficacy owing to poor stability and rapid clearance, as well as the generation of inflammatory or anti-inflammatory responses. [000529] LNPs can also be comprised of hydrophobic lipids, hydrophilic lipids, or both hydrophobic and hydrophilic lipids.

[000530] Any lipid or combination of lipids that are known in the art can be used to produce a LNP. Examples of lipids used to produce LNPs are: DOTMA, DOSPA, DOTAP, DMRIE, DC- cholesterol, DOTAP-cholesterol, GAP-DMORIE-DPyPE, and GL67A-DOPE-DMPE- polyethylene glycol (PEG). Examples of cationic lipids are: 98N12-5, C12-200, DLin-KC2- DMA (KC2), DLin-MC3-DMA (MC3), XTC, MD1, and 7C1. Examples of neutral lipids are: DPSC, DPPC, POPC, DOPE, and SM. Examples of PEG-modified lipids are: PEG-DMG, PEG- CerCl4, and PEG-CerC20.

[000531] The lipids can be combined in any number of molar ratios to produce a LNP. In addition, the polynucleotide (s) can be combined with lipid(s) in a wide range of molar ratios to produce a LNP.

[000532] As stated previously, the site-directed polypeptide and genome-targeting nucleic acid can each be administered separately to a cell or a patient. On the other hand, the site-directed polypeptide can be pre-complexed with one or more guide RNAs, or one or more crRNA together with a tracrRNA. The pre-complexed material can then be administered to a cell or a patient. Such pre-complexed material is known as a ribonucleoprotein particle (RNP).

[000533] RNA is capable of forming specific interactions with RNA or DNA. While this property is exploited in many biological processes, it also comes with the risk of promiscuous interactions in a nucleic acid-rich cellular environment. One solution to this problem is the formation of ribonucleoprotein particles (RNPs), in which the RNA is pre-complexed with an endonuclease. Another benefit of the RNP is protection of the RNA from degradation.

[000534] The endonuclease in the RNP can be modified or unmodified. Likewise, the gRNA, crRNA, tracrRNA, or sgRNA can be modified or unmodified. Numerous modifications are known in the art and can be used.

[000535] The endonuclease and sgRNA can be generally combined in a 1: 1 molar ratio.

Alternatively, the endonuclease, crRNA and tracrRNA can be generally combined in a 1 : 1 : 1 molar ratio. However, a wide range of molar ratios can be used to produce a RNP.

[000536] AAV (adeno associated virus)

[000537] A recombinant adeno-associated virus (AAV) vector can be used for delivery.

Techniques to produce rAAV particles, in which an AAV genome to be packaged that includes the polynucleotide to be delivered, rep and cap genes, and helper virus functions are provided to a cell are standard in the art. Production of rAAV typically requires that the following components are present within a single cell (denoted herein as a packaging cell): a rAAV genome, AAV rep and cap genes separate from (i.e.. not in) the rAAV genome, and helper virus functions. The AAV rep and cap genes can be from any AAV serotype for which recombinant virus can be derived, and can be from a different AAV serotype than the rAAV genome ITRs, including, but not limited to, AAV serotypes described herein. Production of pseudotyped rAAV is disclosed in, for example, international patent application publication number WO 01/83692.

[000538] AAV sequences disclosed herein can comprise sgRNAs that target one or more of the R838H mutation within the GUCY2D gene, the R838C mutation within the GUCY2D gene, and the R838S mutation within the GUCY2D gene. For example, pSIA0l2 comprises an AAV sequence (SEQ ID NO: 5506) that encodes a sgRNA that targets the R838H mutation within the GUCY2D gene (SEQ ID NO: 5464). SEQ ID NO: 5464 is SEQ ID NOs: 5285 (sgRNA protospacer sequence) and 5267 (sgRNA backbone sequence). Another plasmid (SEQ ID NO: 5470) comprises an AAV sequence that encodes a sgRNA that targets the R838H mutation within the GUCY2D gene (SEQ ID NO: 5465). SEQ ID NO: 5465 is SEQ ID NOs: 5286 (sgRNA protospacer sequence) and 5267 (sgRNA backbone sequence). pSIA0l5 comprises an AAV sequence (SEQ ID NO: 5507) that encodes a sgRNA that targets either the R838H mutation or the R838C mutation within the GUCY2D gene (SEQ ID NO: 5466). SEQ ID NO: 5466 is SEQ ID NOs: 5398 (sgRNA protospacer sequence) and 5267 (sgRNA backbone sequence).

[000539] AAV Serotypes

[000540] AAV particles packaging polynucleotides encoding compositions of the present disclosure, e.g., endonucleases, donor sequences, or RNA guide molecules, of the present disclosure can comprise or be derived from any natural or recombinant AAV serotype.

According to the present disclosure, the AAV particles can utilize or be based on a serotype selected from any of the following serotypes, and variants thereof including but not limited to AAV1, AAV 10, AAVl06.l/hu.37, AAV11, AAVl l4.3/hu.40, AAV 12, AAVl27.2/hu.4l, AAVl27.5/hu.42, AAVl28.l/hu.43, AAVl28.3/hu.44, AAVl30.4/hu.48, AAVl45. l/hu.53, AAVl45.5/hu.54, AAVl45.6/hu.55, AAVl6.l2/hu. l l, AAV16.3, AAVl6.8/hu.lO,

AAVl6l. l0/hu.60, AAVl6l.6/hu.6l, AAVl-7/rh.48, AAVl-8/rh.49, AAV2, AAV2.5T, AAV2- l5/rh.62, AAV223.1, AAV223.2, AAV223.4, AAV223.5, AAV223.6, AAV223.7, AAV2- 3/rh.6l, AAV24.1, AAV2-4/rh.50, AAV2-5/rh.5 l, AAV27.3, AAV29.3/bb. l, AAV29.5/bb.2, AAV2G9, AAV-2-pre-miRNA-lOl, AAV3, AAV3.l/hu.6, AAV3.l/hu.9, AAV3-1 l/rh.53, AAV3-3, AAV33. l2/hu.l7, AAV33.4/hu. l5, AAV33.8/hu.l6, AAV3-9/rh.52, AAV3a, AAV3b, AAV4, AAV4-l9/rh.55, AAV42.12, AAV42-10, AAV42-11, AAV42-12, AAV42-13, AAV42- 15, AAV42-lb, AAV42-2, AAV42-3a, AAV42-3b, AAV42-4, AAV42-5a, AAV42-5b, AAV42- 6b, AAV42-8, AAV42-aa, AAV43-1, AAV43-12, AAV43-20, AAV43-21, AAV43-23, AAV43- 25, AAV43-5, AAV4-4, AAV44.1, AAV44.2, AAV44.5, AAV46.2/hu.28, AAV46.6/hu.29, AAV4-8/rl 1.64, AAV4-8/rh.64, AAV4-9/rh.54, AAV5, AAV52. l/hu.20, AAV52/hu.l9, AAV5- 22/rh.58, AAV5-3/rh.57, AAV54.l/hu.2l, AAV54.2/hu.22, AAV54.4R/hu.27, AAV54.5/hu.23, AAV54.7/hu.24, AAV58.2/hu.25, AAV6, AAV6.1, AAV6.1.2, AAV6.2, AAV7, AAV7.2, AAV7.3/hu.7, AAV8, AAV-8b, AAV-8h, AAV9, AAV9.11, AAV9.13, AAV9.16, AAV9.24, AAV9.45, AAV9.47, AAV9.61, AAV9.68, AAV9.84, AAV9.9, AAVA3.3, AAVA3.4, AAVA3.5, AAVA3.7, AAV-b, AAVC1, AAVC2, AAVC5, AAVCh.5, AAVCh.5Rl, AAVcy.2, AAVcy.3, AAVcy.4, AAVcy.5, AAVCy.5Rl, AAVCy.5R2, AAVCy.5R3, AAVCy.5R4, AAVcy.6, AAV-DJ, AAV-DJ8, AAVF3, AAVF5, AAV-h, AAVH-l/hu.l, AAVH2, AAVH- 5/hu.3, AAVH6, AAVhEl. l, AAVhERU4, AAVhErl.l6, AAVhErl.l8, AAVhERl.23, AAVhErl.35, AAVhErl.36, AAVhErl.5, AAVhErl.7, AAVhErl.8, AAVhEr2. l6,

AAVhEr2.29, AAVhEr2.30, AAVhEr2.3 l, AAVhEr2.36, AAVhEr2.4, AAVhEr3.l, AAVhu.l, AAVhu.10, AAVhu.11, AAVhu.11, AAVhu.12, AAVhu.13, AAVhu.14/9, AAVhu.15,

AAVhu.l 6, AAVhu.17, AAVhu.18, AAVhu.19, AAVhu.2, AAVhu.20, AAVhu.2l, AAVhu.22, AAVhu.23.2, AAVhu.24, AAVhu.25, AAVhu.27, AAVhu.28, AAVhu.29, AAVhu.29R, AAVhu.3, AAVhu.3 l, AAVhu.32, AAVhu.34, AAVhu.35, AAVhu.37, AAVhu.39, AAVhu.4, AAVhu.40, AAVhu.41, AAVhu.42, AAVhu.43, AAVhu.44, AAVhu.44Rl, AAVhu.44R2, AAVhu.44R3, AAVhu.45, AAVhu.46, AAVhu.47, AAVhu.48, AAVhu.48Rl, AAVhu.48R2, AAVhu.48R3, AAVhu.49, AAVhu.5, AAVhu.5 l, AAVhu.52, AAVhu.53, AAVhu.54,

AAVhu.55, AAVhu.56, AAVhu.57, AAVhu.58, AAVhu.6, AAVhu.60, AAVhu.6l, AAVhu.63, AAVhu.64, AAVhu.66, AAVhu.67, AAVhu.7, AAVhu.8, AAVhu.9, AAVhu.t 19, AAVLG- l0/rh.40, AAVLG-4/rh.38, AAVLG-9/hu.39, AAVLG-9/hu.39, AAV-LK01, AAV-LK02, AAVLK03, AAV-LK03, AAV-LK04, AAV-LK05, AAV-LK06, AAV-LK07, AAV-LK08, AAV-LK09, AAV-LK10, AAV-LK11, AAV-LK12, AAV-LK13, AAV-LK14, AAV-LK15, AAV-LK17, AAV-LK18, AAV-LK19, AAVN72l-8/rh.43, AAV-PAEC, AAV-PAEC11, AAV- PAEC12, AAV-PAEC2, AAV-PAEC4, AAV-PAEC6, AAV-PAEC7, AAV-PAEC8, AAVpi.l, AAVpi.2, AAVpi.3, AAVrh.lO, AAVrh.l2, AAVrh.l3, AAVrh.l3R, AAVrh.l4, AAVrh. l7, AAVrh. l8, AAVrh. l9, AAVrh.2, AAVrh.20, AAVrh.2l, AAVrh.22, AAVrh.23, AAVrh.24, AAVrh.25, AAVrh.2R, AAVrh.3l, AAVrh.32, AAVrh.33, AAVrh.34, AAVrh.35, AAVrh.36, AAVrh.37, AAVrh.37R2, AAVrh.38, AAVrh.39, AAVrh.40, AAVrh.43, AAVrh.44, AAVrh.45, AAVrh.46, AAVrh.47, AAVrh.48, AAVrh.48, AAVrh.48. l, AAVrh.48. l .2, AAVrh.48.2, AAVrh.49, AAVrh.50, AAVrh.5 l, AAVrh.52, AAVrh.53, AAVrh.54, AAVrh.55, AAVrh.56, AAVrh.57, AAVrh.58, AAVrh.59, AAVrh.60, AAVrh.6l, AAVrh.62, AAVrh.64, AAVrh.64Rl, AAVrh.64R2, AAVrh.65, AAVrh.67, AAVrh.68, AAVrh.69, AAVrh.70, AAVrh.72, AAVrh.73, AAVrh.74, AAVrh.8, AAVrh.8R, AAVrh8R, AAVrh8R A586R mutant, AAVrh8R R533A mutant, BAAV, BNP61 AAV, BNP62 AAV, BNP63 AAV, bovine AAV, caprine AAV, Japanese AAV 10, true type AAV (ttAAV), UPENN AAV 10, AAV-LK16, AAAV, AAV Shuffle 100-1, AAV Shuffle 100-2, AAV Shuffle 100-3, AAV Shuffle 100-7, AAV Shuffle 10- 2, AAV Shuffle 10-6, AAV Shuffle 10-8, AAV SM 100-10, AAV SM 100-3, AAV SM 10-1, AAV SM 10-2, and/or AAV SM 10-8.

[000541] In some examples, the AAV serotype can be, or have, a mutation in the AAV9 sequence as described by N Pulicherla et al. (Molecular Therapy 19(6): 1070-1078 (2011), such as but not limited to, AAV9.9, AAV9.11, AAV9.13, AAV9.16, AAV9.24, AAV9.45, AAV9.47, AAV9.61, AAV9.68, AAV9.84.

[000542] In some examples, the AAV serotype can be, or have, a sequence as described in United States Patent No. US 6156303, such as, but not limited to, AAV3B (SEQ ID NO: 1 and 10 of US 6156303), AAV6 (SEQ ID NO: 2, 7 and 11 of US 6156303), AAV2 (SEQ ID NO: 3 and 8 of US 6156303), AAV3A (SEQ ID NO: 4 and 9, of US 6156303), or derivatives thereof.

[000543] In some examples, the serotype can be AAVDJ or a variant thereof, such as AAVDJ8 (or AAV-DJ8), as described by Grimm et al. (Journal of Virology 82(12): 5887-5911 (2008)). The amino acid sequence of AAVDJ8 can comprise two or more mutations in order to remove the heparin binding domain (HBD). As a non-limiting example, the AAV-DJ sequence described as SEQ ID NO: 1 in U.S. Patent No. 7,588,772, can comprise two mutations: (1) R587Q where arginine (R; Arg) at amino acid 587 is changed to glutamine (Q; Gln) and (2) R590T where arginine (R; Arg) at amino acid 590 is changed to threonine (T; Thr). As another non-limiting example, can comprise three mutations: (1) K406R where lysine (K; Lys) at amino acid 406 is changed to arginine (R; Arg), (2) R587Q where arginine (R; Arg) at amino acid 587 is changed to glutamine (Q; Gln) and (3) R590T where arginine (R; Arg) at amino acid 590 is changed to threonine (T; Thr).

[000544] In some examples, the AAV serotype can be, or have, a sequence as described in International Publication No. WO2015121501, such as, but not limited to, true type AAV (ttAAV) (SEQ ID NO: 2 of WO2015121501),“UPenn AAV 10” (SEQ ID NO: 8 of

W02015121501),“Japanese AAV 10” (SEQ ID NO: 9 ofW020l5 l2l50l), or variants thereof. [000545] According to the present disclosure, AAV capsid serotype selection or use can be from a variety of species. In one example, the AAV can be an avian AAV (AAAV). The AAAV serotype can be, or have, a sequence as described in United States Patent No. US 9238800, such as, but not limited to, AAAV (SEQ ID NO: 1, 2, 4, 6, 8, 10, 12, and 14 of US 9,238,800), or variants thereof.

[000546] In one example, the AAV can be a bovine AAV (BAAV). The BAAV serotype can be, or have, a sequence as described in United States Patent No. US 9, 193,769, such as, but not limited to, BAAV (SEQ ID NO: 1 and 6 of US 9193769), or variants thereof. The BAAV serotype can be or have a sequence as described in United States Patent No. US7427396, such as, but not limited to, BAAV (SEQ ID NO: 5 and 6 of US7427396), or variants thereof.

[000547] In one example, the AAV can be a caprine AAV. The caprine AAV serotype can be, or have, a sequence as described in United States Patent No. US7427396, such as, but not limited to, caprine AAV (SEQ ID NO: 3 of US7427396), or variants thereof.

[000548] In other examples the AAV can be engineered as a hybrid AAV from two or more parental serotypes. In one example, the AAV can be AAV2G9 which comprises sequences from AAV2 and AAV9. The AAV2G9 AAV serotype can be, or have, a sequence as described in United States Patent Publication No. US20160017005.

[000549] In one example, the AAV can be a serotype generated by the AAV9 capsid library with mutations in amino acids 390-627 (VP1 numbering) as described by Pulicherla et al.

(Molecular Therapy 19(6): 1070-1078 (2011). The serotype and corresponding nucleotide and amino acid substitutions can be, but is not limited to, AAV9.1 (G1594C; D532H), AAV6.2 (T1418A and T1436X; V473D and I479K), AAV9.3 (T1238A; F413Y), AAV9.4 (T1250C and A1617T; F417S), AAV9.5 (A1235G, A1314T, A1642G, C1760T; Q412R, T548A, A587V), AAV9.6 (T1231A; F411I), AAV9.9 (G1203A, G1785T; W595C), AAV9.10 (A1500G, T1676C; M559T), AAV9.11 (A1425T, A1702C, A1769T; T568P, Q590L), AAV9.13 (A1369C, A1720T; N457H, T574S), AAV9.14 (T1340A, T1362C, T1560C, G1713A; L447H), AAV9.16 (A1775T; Q592L), AAV9.24 (T1507C, T1521G; W503R), AAV9.26 (A1337G, A1769C; Y446C, Q590P), AAV9.33 (A1667C; D556A), AAV9.34 (A1534G, C1794T; N512D), AAV9.35 (A1289T, T1450A, C1494T, A1515T, C1794A, G1816A; Q430L, Y484N, N98K, V606I), AAV9.40 (A1694T, E565V), AAV9.41 (A1348T, T1362C; T450S), AAV9.44 (A1684C, A1701T, A1737G; N562H, K567N), AAV9.45 (A1492T, C1804T; N498Y, L602F), AAV9.46 (G1441C, T1525C, T1549G; G481R, W509R, L517V), 9.47 (G1241A, G1358A, A1669G, C1745T;

S414N, G453D, K557E, T582I), AAV9.48 (C1445T, A1736T; P482L, Q579L), AAV9.50 (A1638T, C1683T, T1805A; Q546H, L602H), AAV9.53 (G1301A, A1405C, C1664T, G1811T; R134Q, S469R, A555V, G604V), AAV9.54 (C1531A, T1609A; L511I, L537M), AAV9.55 (T1605A; F535L), AAV9.58 (C1475T, C1579A; T492I, H527N), AAV.59 (T1336C; Y446H), AAV9.61 (A1493T; N498I), AAV9.64 (C1531A, A1617T; L511I), AAV9.65 (C1335T,

T1530C, C1568A; A523D), AAV9.68 (C1510A; P504T), AAV9.80 (Gl44lA,;G48lR), AAV9.83 (C1402A, A1500T; P468T, E500D), AAV9.87 (T1464C, T1468C; S490P), AAV9.90 (Al 196T; Y399F), AAV9.91 (T1316G, A1583T, C1782G, T1806C; L439R, K528I), AAV9.93 (A1273G, A1421G, A1638C, C1712T, G1732A, A1744T, A1832T; S425G, Q474R, Q546H, P571L, G578R, T582S, D611V), AAV9.94 (A1675T; M559L) and AAV9.95 (T1605A; F535L).

[000550] In one example, the AAV can be a serotype comprising at least one AAV capsid CD8+ T-cell epitope. As a non-limiting example, the serotype can be AAV1, AAV2 or AAV8.

[000551] In one example, the AAV can be a variant, such as PHP.A or PHP.B as described in Deverman. 2016. Nature Biotechnology. 34(2): 204-209.

[000552] In one example, the AAV can be a serotype selected from any of those found in SEQ ID NOs: 4697-5265 and Table 5.

[000553] In one example, the AAV can be encoded by a sequence, fragment or variant as described in SEQ ID NOs: 4697-5265 and Table 5.

[000554] A method of generating a packaging cell involves creating a cell line that stably expresses all of the necessary components for AAV particle production. For example, a plasmid (or multiple plasmids) comprising a rAAV genome lacking AAV rep and cap genes, AAV rep and cap genes separate from the rAAV genome, and a selectable marker, such as a neomycin resistance gene, are integrated into the genome of a cell. AAV genomes have been introduced into bacterial plasmids by procedures such as GC tailing (Samulski et al., 1982, Proc. Natl.

Acad. S6. USA, 79:2077-2081), addition of synthetic linkers containing restriction endonuclease cleavage sites (Laughlin et al., 1983, Gene, 23:65-73) or by direct, blunt-end ligation (Senapathy & Carter, 1984, J. Biol. Chem., 259:4661-4666). The packaging cell line can then be infected with a helper virus, such as adenovirus. The advantages of this method are that the cells are selectable and are suitable for large-scale production of rAAV. Other examples of suitable methods employ adenovirus or baculovirus, rather than plasmids, to introduce rAAV genomes and/or rep and cap genes into packaging cells.

[000555] General principles of rAAV production are reviewed in, for example, Carter, 1992, Current Opinions in Biotechnology, 1533-539; and Muzyczka, 1992, Curr. Topics in Microbial and Immunol., 158:97-129). Various approaches are described in Ratschin et al., Mol. Cell. Biol. 4:2072 (1984); Hermonat et al., Proc. Natl. Acad. Sci. USA, 81 :6466 (1984); Tratschin et al., Mol . Cell. Biol. 5:3251 (1985); McLaughlin et al., J. Virol., 62: 1963 (1988); and Lebkowski et al, 1988 Mol. Cell. Biol., 7:349 (1988). Samulski et al. (1989, J. Virol., 63:3822-3828); U.S. Patent No. 5,173,414; WO 95/13365 and corresponding U.S. Patent No. 5,658.776 ; WO 95/13392; WO 96/17947; PCT/US98/18600; WO 97/09441 (PCT/US96/14423); WO 97/08298

(PCT/US96/13872); WO 97/21825 (PCT/US96/20777); WO 97/06243 (PCT/FR96/01064); WO 99/11764; Perrin et al. (1995) Vaccine 13: 1244-1250; Paul et al. (1993) Human Gene Therapy 4:609-615; Clark et al. (1996) Gene Therapy 3: 1124-1132; U.S. Patent. No. 5,786,211; U.S. Patent No. 5,871,982; and U.S. Patent. No. 6,258,595.

[000556] AAV vector serotypes can be matched to target cell types. For example, the following exemplary cell types can be transduced by the indicated AAV serotypes among others. See Table 5.

Table 5: Tissue/Cell Types and Serotypes

[000557] In addition to adeno-associated viral vectors, other viral vectors can be used. Such viral vectors include, but are not limited to, lentivirus, alphavirus, enterovirus, pestivirus, baculovirus, herpesvirus, Epstein Barr virus, papovavirusr, poxvirus, vaccinia virus, and herpes simplex virus.

[000558] In some cases, Cas9 mRNA, sgRNA targeting one or two loci in GUCY2D gene, and donor DNA can each be separately formulated into lipid nanoparticles, or are all co-formulated into one lipid nanoparticle.

[000559] In some cases, Cas9 mRNA can be formulated in a lipid nanoparticle, while sgRNA and donor DNA can be delivered in an AAV vector. [000560] Options are available to deliver the Cas9 nuclease as a DNA plasmid, as mRNA or as a protein. The guide RNA can be expressed from the same DNA, or can also be delivered as an RNA. The RNA can be chemically modified to alter or improve its half-life, or decrease the likelihood or degree of immune response. The endonuclease protein can be complexed with the gRNA prior to delivery. Viral vectors allow efficient delivery; split versions of Cas9 and smaller orthologs of Cas9 can be packaged in AAV, as can donors for HDR. A range of non-viral delivery methods also exist that can deliver each of these components, or non-viral and viral methods can be employed in tandem. For example, nanoparticles can be used to deliver the protein and guide RNA, while AAV can be used to deliver a donor DNA.

[000561] Self-Inactivating (SIN) CRISPR-Cas systems

[000562] Disclosed herein are“self-inactivating” (SIN) CRISPR-Cas systems. The SIN CRISPR-Cas system can comprise one or more segments. The SIN CRISPR-Cas system can be an AAV system. The SIN CRISPR-Cas system can be an AAV5 system.

[000563] A first segment can comprise a nucleotide sequence that encodes one or more polypeptide inducing site-directed mutagenesis (e.g. Cas9 or Cpfl). The first segment can further comprise a start codon, a stop codon, and a poly (A) termination site. Such a polypeptide can be Streptococcus pyogenes Cas9 (SpCas9), Staphylococcus aureus Cas9 (SaCas9), or any variants thereof. A nucleotide sequence functioning as a promoter can be operably linked to the first segment. The promoter can be a spatially-restricted promoter, bidirectional promoter driving sgRNA in one direction and Cas9 in the opposite orientation, or an inducible promoter. The spatially-restricted promoter can be selected from the group consisting of: any ubiquitous promoter, any tissue or cell type specific promoter, a hepatocyte-specific promoter, a neuron- specific promoter, an adipocyte-specific promoter, a cardiomyocyte-specific promoter, a skeletal muscle-specific promoter, lung progenitor cell specific promoter, a photoreceptor-specific promoter, and a retinal pigment epithelial (RPE) selective promoter. The promoter can be a sEFla promoter or GRK1 promoter.

[000564] A second segment can comprise a nucleotide sequence that encodes a sgRNA. The sgRNA can comprise any of SEQ ID NOs: 5282-5313 (Figure 2A), 5398-5409, 5434-5443 (Figure 2D) and 5464-5466. The sgRNAs can be substantially complementary to a SIN site and a genomic target sequence. By "hybridizable" or "complementary" or "substantially

complementary" it is meant that a nucleic acid (e.g. RNA) comprises a sequence of nucleotides that enables it to non-covalently bind, e.g.: form Watson-Crick base pairs, "anneal", or

"hybridize," to another nucleic acid in a sequence-specific, antiparallel manner (i.e., a nucleic acid specifically binds to a complementary nucleic acid) under the appropriate in vitro and/or in vivo conditions of temperature and solution ionic strength. As is known in the art, standard Watson-Crick base-pairing includes: adenine (A) pairing with thymidine (T), adenine (A) pairing with uracil (U), and guanine (G) pairing with cytosine (C) [DNA, RNA] . In some examples, the sgRNAs may be fully complementary to the nucleotide sequence of the SIN site except for in at least one location. In some examples, the sgRNAs may be fully complementary to the nucleotide sequence of the SIN site except for in at least two locations.

[000565] One or more third segments can be located at a 5’ end of the first segment (upstream of the start codon and/or downstream of the transcriptional start site) or at a 3’ end of a first segment (between the stop codon and poly (A) termination site). The one or more third segments can be located at the 5’ end of the first segment and the 3’ end of a first segment. The third segment can be less than 100 nucleotides in length. For example, the third segment can be 20-99, 30-99, 40-99, 50-99, 60-99, 70-99, 80-99, and 90-99 nucleotides in length. The third segment can be less than 50 nucleotides in length. For example, the third segment can be 20-49, 25-49, 30-49, 35-49, 40-49, and 45-49 nucleotides in length.

[000566] The one or more third segments can comprise a self-inactivating (SIN) site. The SIN site or R838 target site, as used herein, is either (1) a 20-50 nucleotide sequence of the GUCY2D gene comprising the R838H mutation (SEQ ID NO: 5478, 5479, and 5480), (2) a 20-50 nucleotide sequence of the GUCY2D gene comprising the R838C mutation (SEQ ID NOs: 5481, 5482, and 5483), (3) a 20-50 nucleotide sequence of the GUCY2D gene comprising the R838S mutation (SEQ ID NOs: 5484, 5485, and 5486), (4) a 20-50 nucleotide sequence of the

GUCY2D gene comprising a combination of the R838C mutation and R838H mutation (SEQ ID NOs: 5490, 5491, and 5492), or (5) a 20-50 nucleotide sequence of the GUCY2D gene comprising a combination of the R838S mutation and R838H mutation (SEQ ID NOs: 5487, 5488, and 5489) (Table 6). The SIN site comprises protospacer adjacent motifs (PAMs).

Table 6

[000567] The spacer sequence of a gRNA or sgRNA hybridizes to the strand complementary to the protospacer sequence located within the SIN site, which leads to editing by the gRNA- endonuclease complex or the sgRNA-endonuclease complex and eventually results in inactivation of the endonuclease (e.g. Cas9 or Cpfl). SIN sites that comprise a 20-50 nucleotide sequence of the GUCY2D gene comprising the R838H mutation can be targeted with any of the sgRNAs comprising SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 even though one or more of the sgRNAs may not be fully complementary to the nucleotide sequence of the SIN site in at least 1-2 locations. SIN sites that comprise a 20-50 nucleotide sequence of the GUCY2D gene comprising the R838C mutation can be targeted with any of the sgRNAs comprising SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 even though one or more of these sgRNAs may not be fully complementary to the nucleotide sequence of the SIN site in at least 1-2 locations. SIN sites that comprise a 20-50 nucleotide sequence of the GUCY2D gene comprising the R838S mutation can be targeted with any of the sgRNAs comprising SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 even though one or more of these sgRNAs may not be fully complementary to the nucleotide sequence of the SIN site in at least 1-2 locations. SIN sites that comprise a 20-50 nucleotide sequence of the GUCY2D gene comprising a combination of both the R838C mutation and R838H mutation can be targeted with any of the sgRNAs comprising SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 even though one or more of these sgRNAs may not be fully complementary to the nucleotide sequence of the SIN site in at least 1-2 locations. SIN sites that comprise a 20-50 nucleotide sequence of the GUCY2D gene comprising a combination of both the R838S mutation and R838H mutation can be targeted with any of the sgRNAs comprising SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 even though one or more of these sgRNAs may not be fully complementary to the nucleotide sequence of the SIN site in at least 1-2 locations. [000568] In other examples, the SIN site can be shorter in length compared to the sequences listed in Table 6. For example, the SIN site can be any one of the sequences in SEQ ID NOs: 5324-5355 (Figure 2B) and a PAM. The SIN site can be any one of the sequences in 5410-5421 (Figure 2E) and a PAM. The SIN site can be any one of the sequences in 5444-5453 (Figure 2E) and a PAM. The SIN site can be any one of the sequences in SEQ ID NOs: 5366-5397 (Figure 2C) and a PAM. The SIN site can be any one of the sequences in SEQ ID NOs: 5422-5433 (Figure 2F) and a PAM. The SIN site can be any one of the sequences in 5454-5463 (Figure 2F) and a PAM.

[000569] In other examples, the SIN site can be shorter than the corresponding protospacer sequence of the sgRNA. For example, a protospacer sequence for a sgRNA may be 20 nucleotides in length whereas the corresponding SIN site may be shorter (only 19, 18, or 17 nucleotides in length) and a PAM. This shortened SIN site (that still corresponds to the spacer sequence of the sgRNA) will allow the genomic target sequence to be cleaved more efficiently than the shortened SIN site. For this reason, any one of the sequences in SEQ ID NOs: 5324- 5355 (Figure 2B), SEQ ID NOs: 5410-5421 (Figure 2E), SEQ ID NOs: 5444-5453 (Figure 2E), SEQ ID NOs: 5366-5397 (Figure 2C), SEQ ID NOs: 5422-5433 (Figure 2F), and SEQ ID NOs: 5454-5463 (Figure 2F) can be shortened by 1, 2, or 3 nucleotides and used as a SIN site along with a PAM sequence. In these examples, the SIN sites may be less than 20 nucleotides in length.

[000570] In the SIN-AAV system, the endonuclease can be guided by one or more sgRNAs to one or more genomic target sequences. The one or more genomic target sequences can be a R838H mutation within the GUCY2D gene, a R838C mutation within the GUCY2D gene, or a R838S mutation within the GUCY2D gene. The endonuclease can be further guided to the SIN- AAV system that is expressing the endonuclease and the system’s components. Examples of SIN-AAV system components that can be targeted include: essential sequences of a vector of the SIN-AAV system (e.g. viral inverted terminal repeats), promoters driving expression of genes important for editing (e.g. sgRNA or endonuclease genes), the open reading frame (ORF) of Cas9 or Cpfl, introns of encoded genes, or non-coding regions located 5’ or 3’ of the Cas9 or Cpfl ORF (SIN sites). This leads to self-limiting editing activity which results in editing of one or more target genomic loci, and, thereafter, reduced or eliminated expression of the

endonuclease and/or other essential components of the system (e.g. sgRNAs). This self-limited expression of genes in the SIN-AAV system can result in reduced off-target editing and reduced risk of successfully edited cells being targeted by the patient’s immune system. [000571] One or more vectors can encode the disclosed SIN-AAV systems. If only one vector encodes the entire SIN-AAV system, then the system is referred to as an“all-in-one” SIN system. For example, the first segment, second segment, and third segment can be provided together in an“all-in-one” SIN AAV system. If two vectors encode the entire SIN-AAV system, then the system is referred to as an“all-in-two” SIN system. For example, the first segment and third segment can be provided in a first vector and the second segment can be provided in a second vector for an“all-in-two” SIN AAV system.

[000572] All-in-one SIN-AAV systems

[000573] In one example, an all-in-one SIN system can comprise a vector comprising an endonuclease ORF and a sgRNA gene. The vector can further comprise SIN sites at locations 5’ and 3’ of the endonuclease ORF. The sgRNA can be substantially complementary to the SIN site. The sgRNA can also be substantially complementary to a genomic target sequence. Thus, the sequence of the sgRNA is such that it can hybridize with both the SIN sites on the vector and with one or more genomic target sequences. When hybridizing with the one or more genomic targets or with the SIN sites, the sgRNA may comprise one or more mismatched bases. The system can lead to self-limited editing at the targeted genomic loci, followed by excision and/or inactivation of the endonuclease gene.

[000574] In another example, an all-in-one SIN system can comprise a vector comprising an endonuclease ORF, a first sgRNA gene, and a second sgRNA gene. The vector can further comprise SIN sites at locations 5’ and 3’ of the endonuclease ORF. The sequence of the first sgRNA is such that it can hybridize with one or more genomic target sequences. The sequence of the second sgRNA is such that it can hybridize with the SIN sites on the vector. When hybridizing with the one or more genomic targets or with the SIN sites, the sgRNAs can comprise one or more mismatched bases. Additional sgRNAs can be incorporated into the system to allow for editing of additional genomic or SIN system targets. The system can lead to self-limited editing at the targeted genomic loci, followed by excision and/or inactivation of the endonuclease gene.

[000575] In another example, an all-in-one SIN system can comprise a vector comprising an endonuclease ORF, a first sgRNA gene, and a second sgRNA gene. The sequence of the first sgRNA is such that it can hybridize with one or more genomic target sequences. The sequence of the second sgRNA is such that it can hybridize within or near the endonuclease ORF (Cas9 or Cpfl) on the vector, leading to inactivation of the endonuclease gene via indel generation.

Additional sgRNAs can be incorporated into the system to allow for editing of additional genomic or SIN system targets. When hybridizing with the one or more genomic targets or the endonuclease ORF, the two or more sgRNAs may comprise one or more mismatched bases. The system can lead to self-limited editing at the targeted genomic loci, followed by inactivation of the endonuclease gene.

[000576] In all-in-one systems such as those described above, production of appropriate viral vectors can be challenging due to inactivation of the endonuclease gene that occurs earlier than desired and accumulation of mutagenized SIN sites on DNA packaged in AAV capsids (e.g. during production and packaging of the viral vector in a cell line of choice). To solve this problem, the endonuclease ORF and/or the sgRNA genes that direct editing at the endonuclease gene locus can be expressed from one or more cell/tissue-specific promoters. The cell/tissue specific promoters can be active in the cells where editing is desired and inactive earlier in the cells used for production and packaging of the vectors. In addition, one or more inducible promoter systems can be used to control expression of genes of interest, such as tetracycline- controlled transcriptional activation (i.e. tet-ON or tet-OFF). Other solutions to the premature inactivation problem include regulating gene expression with miRNAs, small interfering RNAs, short hairpin RNAs, other antisense oligonucleotides, blocking transcription of sgRNA (e.g. the use of a tet-OFF system), or inhibiting sgRNA loading onto Cas9.

[000577] All-in-two SIN-AAV systems

[000578] In one example, an all-in-two SIN system can comprise a first vector to provide an ORF encoding an endonuclease (Figures 11A-B or 14A-B). SIN sites can flank the

endonuclease ORF at 5’ and 3’ locations on the first vector (Figure 1 1A-B or 14A-B). The SIN site can be any one of SEQ ID NOs: 5478-5492, as shown in Table 6. The SIN site can be shorter in length compared to the sequences listed in Table 6. For example, the SIN site can be any one of the sequences in SEQ ID NOs: 5324-5355 (Figure 2B) and a PAM. The SIN site can be any one of the sequences in 5410-5421 (Figure 2E) and a PAM. The SIN site can be any one of the sequences in 5444-5453 (Figure 2E) and a PAM. The SIN site can be any one of the sequences in SEQ ID NOs: 5366-5397 (Figure 2C) and a PAM. The SIN site can be any one of the sequences in SEQ ID NOs: 5422-5433 (Figure 2F) and a PAM. The SIN site can be any one of the sequences in 5454-5463 (Figure 2F) and a PAM. In other examples, the SIN site can be shorter than the corresponding protospacer sequence of the sgRNA. For example, a protospacer sequence for a sgRNA may be 20 nucleotides in length whereas the corresponding SIN site may be shorter (only 19, 18, or 17 nucleotides in length) and a PAM. This shortened SIN site (that still corresponds to the spacer sequence of the sgRNA) will allow the genomic target sequence to be cleaved more efficiently than the shortened SIN site. For this reason, any one of the sequences in SEQ ID NOs: 5324-5355 (Figure 2B), SEQ ID NOs: 5410-5421 (Figure 2E), SEQ ID NOs: 5444-5453 (Figure 2E), SEQ ID NOs: 5366-5397 (Figure 2C), SEQ ID NOs: 5422- 5433 (Figure 2F), and SEQ ID NOs: 5454-5463 (Figure 2F) can be shortened by 1, 2, or 3 nucleotides and used as a SIN site along with a PAM sequence. In a second vector, a single sgRNA can be encoded (Figure 11D). The sgRNA can comprise any of SEQ ID NOs: 5282- 5313 (Figure 2A), 5398-5409 (Figure 2D), 5434-5443 (Figure 2D) and 5464-5466. The sgRNA can be substantially complementary to the SIN site. The sgRNA can also be substantially complementary to a genomic target sequence. Thus, the sequence of the sgRNA can be such that it can hybridize with both the SIN sites on the first vector and with one or more genomic target sequences (e.g. the R838H mutation within GUCY2D, the R838C mutation within GUCY2D, or the R838S mutation within GUCY2D). When hybridizing with the one or more genomic targets or with the SIN sites, the sgRNA may comprise one or more mismatched bases. The system can lead to self-limited editing at the targeted genomic loci, followed by excision and/or inactivation of the endonuclease gene.

[000579] In another example, an all-in-two SIN system can comprise a first vector to provide an ORF encoding an endonuclease. SIN sites can flank the endonuclease ORF at 5’ and 3’ locations on the first vector. The SIN site can be any one of SEQ ID NOs: 5478-5492, as shown in Table 6. The SIN site can be shorter in length compared to the sequences listed in Table 6.

For example, the SIN site can be any one of the sequences in SEQ ID NOs: 5324-5355 (Figure 2B) and a PAM. The SIN site can be any one of the sequences in 5410-5421 (Figure 2E) and a PAM. The SIN site can be any one of the sequences in 5444-5453 (Figure 2E) and a PAM. The SIN site can be any one of the sequences in SEQ ID NOs: 5366-5397 (Figure 2C) and a PAM. The SIN site can be any one of the sequences in SEQ ID NOs: 5422-5433 (Figure 2F) and a PAM. The SIN site can be any one of the sequences in 5454-5463 (Figure 2F) and a PAM. In other examples, the SIN site can be shorter than the corresponding protospacer sequence of the sgRNA. For example, a protospacer sequence for a sgRNA may be 20 nucleotides in length whereas the corresponding SIN site may be shorter (only 19, 18, or 17 nucleotides in length) and a PAM. This shortened SIN site (that still corresponds to the spacer sequence of the sgRNA) will allow the genomic target sequence to be cleaved more efficiently than the shortened SIN site. For this reason, any one of the sequences in SEQ ID NOs: 5324-5355 (Figure 2B), SEQ ID NOs: 5410-5421 (Figure 2E), SEQ ID NOs: 5444-5453 (Figure 2E), SEQ ID NOs: 5366-5397 (Figure 2C), SEQ ID NOs: 5422-5433 (Figure 2F), and SEQ ID NOs: 5454-5463 (Figure 2F) can be shortened by 1, 2, or 3 nucleotides and used as a SIN site along with a PAM sequence. The all-in-two system can further comprise a second vector, comprising two sgRNA genes. When expressed from the second vector, a first sgRNA can bind with an endonuclease molecule and direct editing at one or more genomic target loci (e.g. the R838H mutation within GUCY2D, the R838C mutation within GUCY2D, or the R838S mutation within GUCY2D). The first sgRNA can comprise any of SEQ ID NOs: 5282-5313 (Figure 2A), 5398-5409, 5434-5443 (Figure 2D) and 5464-5466. When expressed from the second vector, a second sgRNA can bind with an endonuclease molecule and direct editing at the SIN sites. Additional sgRNAs can be incorporated into the system to allow for editing of additional genomic or SIN system targets. When hybridizing with the one or more genomic targets or with the SIN sites, the two or more sgRNAs may comprise one or more mismatched bases. In some examples, the one or more sgRNAs that target genomic loci may be encoded on the first vector, or a combination of both the first and second vectors. The system can lead to self-limited editing at the targeted genomic loci, followed by excision and/or inactivation of the endonuclease gene.

[000580] In another example, an all-in-two SIN system can comprise a first vector comprising an endonuclease ORF, and a second vector comprising two sgRNA genes. When expressed from the second vector, a first sgRNA can bind with an endonuclease molecule and direct editing at one or more genomic target loci (e.g. the R838H mutation within GUCY2D, the R838C mutation within GUCY2D, or the R838S mutation within GUCY2D). The first sgRNA can comprise any of SEQ ID NOs: 5282-5313 (Figure 2A), 5398-5409, 5434-5443 (Figure 2D) and 5464-5466. When expressed from the second vector, a second sgRNA can bind with an endonuclease molecule and direct editing within or near the endonuclease ORF (Cas9 or Cpfl) on the first vector, leading to inactivation of the endonuclease gene via indel generation. Additional sgRNAs can be incorporated into the system to allow for editing of additional genomic or SIN system targets. When hybridizing with the one or more genomic targets or within or near the endonuclease ORF, the two or more sgRNAs may comprise one or more mismatched bases. In some examples, the one or more sgRNAs that target genomic loci may be encoded on the first vector, or a combination of both the first and second vectors. The system can lead to self-limited editing at the targeted genomic loci, followed by inactivation of the endonuclease gene.

[000581] Lentivirus

[000582] In some aspects, lentiviral vectors or particles can be used as delivery vehicles. Fentiviruses (FV) are subgroup of the Retroviridae family of viruses. Fentiviral particles are able to integrate their genetic material into the genome of a target/host cell. Examples of lentivirus include the Human Immunodeficiency Viruses: HIV-l and HIV-2, Jembrana Disease Vims (JDV), equine infectious anemia vims (EIAV), equine infectious anemia vims, visna- maedi and caprine arthritis encephalitis vims (CAEV), the Simian Immunodeficiency Vims (SIV), feline immunodeficiency vims (FIV), bovine immunodeficiency vims (BIV). LV’s are capable of infecting both dividing and non-dividing cells due to their unique ability to pass through a target cell’s intact nuclear membrane Greenberg et al., University of Berkeley, California; 2006). Lentiviral particles that form the gene delivery vehicle are replication defective and are generated by attenuating the HIV vimlence genes. For example, the genes Vpu, Vpr, Nef, Env, and Tat are excised making the vector biologically safe. Lentiviral vehicles, for example, derived from HIV-l/HIV-2 can mediate the efficient delivery, integration and long term expression of transgenes into non-dividing cells. As used herein, the term“recombinant” refers to a vector or other nucleic acid containing both lentiviral sequences and non-lentiviral retroviral sequences.

[000583] In order to produce a lentivims that is capable of infecting host cells, three types of vectors need to be co-expressed in vims producing cells: a backbone vector containing the transgene of interests and self-inactivating 3’-LTR regions, one constmct expressing viral stmcture proteins, and one vector encoding vesicular stomatitis vims glycoprotein (VSVG) for encapsulation (Naldini, L. et al., Science 1996; 272, 263-267). Separation of the Rev gene from other structural genes further increases the biosafety by reducing the possibility of reverse recombination. Cell lines that can be used to produce high-titer lentiviral particles may include, but are not limited to 293T cells, 293FT cells, and 293SF-3F6 cells (Witting et al., Human Gene Therapy, 2012; 23: 243-249; Ansorge et al., Joural of Genetic Medicne, 2009; 11: 868-876).

[000584] Methods for generating recombinant lentiviral particles are discussed in the art, for example, WO 2013076309 (PCT/EP2012/073645); WO 2009153563 (PCT/GB2009/001527); U.S. Pat. NOs.: 7,629,153; and 6, 808, 905.

[000585] Cell types such as photoreceptors, retinal pigment epithelium, and ganglion cells have been successfully targeted with LV vector. The efficiency of delivery to photoreceptors and ganglion cells is significantly higher with AAV than LV vectors.

[000586] Pharmaceutically Acceptable Carriers

[000587] The ex vivo methods of administering progenitor cells to a subject contemplated herein involve the use of therapeutic compositions comprising progenitor cells.

[000588] Therapeutic compositions can contain a physiologically tolerable carrier together with the cell composition, and optionally at least one additional bioactive agent as described herein, dissolved or dispersed therein as an active ingredient. In some cases, the therapeutic composition is not substantially immunogenic when administered to a mammal or human patient for therapeutic purposes, unless so desired.

[000589] In general, the progenitor cells described herein can be administered as a suspension with a pharmaceutically acceptable carrier. One of skill in the art will recognize that a pharmaceutically acceptable carrier to be used in a cell composition will not include buffers, compounds, cryopreservation agents, preservatives, or other agents in amounts that substantially interfere with the viability of the cells to be delivered to the subject. A formulation comprising cells can include e.g., osmotic buffers that permit cell membrane integrity to be maintained, and optionally, nutrients to maintain cell viability or enhance engraftment upon administration. Such formulations and suspensions are known to those of skill in the art and/or can be adapted for use with the progenitor cells, as described herein, using routine experimentation.

[000590] A cell composition can also be emulsified or presented as a liposome composition, provided that the emulsification procedure does not adversely affect cell viability. The cells and any other active ingredient can be mixed with excipients that are pharmaceutically acceptable and compatible with the active ingredient, and in amounts suitable for use in the therapeutic methods described herein.

[000591] Additional agents included in a cell composition can include pharmaceutically acceptable salts of the components therein. Pharmaceutically acceptable salts include the acid addition salts (formed with the free amino groups of the polypeptide) that are formed with inorganic acids, such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, tartaric, mandelic and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases, such as, for example, sodium, potassium, ammonium, calcium or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, 2-ethylamino ethanol, histidine, procaine and the like.

[000592] Physiologically tolerable carriers are well known in the art. Exemplary liquid carriers are sterile aqueous solutions that contain no materials in addition to the active ingredients and water, or contain a buffer such as sodium phosphate at physiological pH value, physiological saline or both, such as phosphate-buffered saline. Still further, aqueous carriers can contain more than one buffer salt, as well as salts such as sodium and potassium chlorides, dextrose, polyethylene glycol and other solutes. Liquid compositions can also contain liquid phases in addition to and to the exclusion of water. Exemplary of such additional liquid phases are glycerin, vegetable oils such as cottonseed oil, and water-oil emulsions. The amount of an active compound used in the cell compositions that is effective in the treatment of a particular disorder or condition can depend on the nature of the disorder or condition, and can be determined by standard clinical techniques.

[000593] Guide RNA Formulation

[000594] Guide RNAs of the present disclosure can be formulated with pharmaceutically acceptable excipients such as carriers, solvents, stabilizers, adjuvants, diluents, etc., depending upon the particular mode of administration and dosage form. Guide RNA compositions can be formulated to achieve a physiologically compatible pH, and range from a pH of about 3 to a pH of about 11, about pH 3 to about pH 7, depending on the formulation and route of administration. In some cases, the pH can be adjusted to a range from about pH 5.0 to about pH 8. In some cases, the compositions can comprise a therapeutically effective amount of at least one compound as described herein, together with one or more pharmaceutically acceptable excipients. Optionally, the compositions can comprise a combination of the compounds described herein, or can include a second active ingredient useful in the treatment or prevention of bacterial growth (for example and without limitation, anti-bacterial or anti-microbial agents), or can include a combination of reagents of the present disclosure.

[000595] Suitable excipients include, for example, carrier molecules that include large, slowly metabolized macromolecules such as proteins, polysaccharides, polylactic acids, polyglycolic acids, polymeric amino acids, amino acid copolymers, and inactive virus particles. Other exemplary excipients can include antioxidants (for example and without limitation, ascorbic acid), chelating agents (for example and without limitation, EDTA), carbohydrates (for example and without limitation, dextrin, hydroxyalkylcellulose, and hydroxyalkylmethylcellulose), stearic acid, liquids (for example and without limitation, oils, water, saline, glycerol and ethanol), wetting or emulsifying agents, pH buffering substances, and the like.

[000596] Administration & Efficacy

[000597] The terms "administering," "introducing" and "transplanting" can be used

interchangeably in the context of the placement of cells, e.g., progenitor cells, into a subject, by a method or route that results in at least partial localization of the introduced cells at a desired site, such as a site of injury or repair, such that a desired effect(s) is produced. The cells e.g., progenitor cells, or their differentiated progeny can be administered by any appropriate route that results in delivery to a desired location in the subject where at least a portion of the implanted cells or components of the cells remain viable. The period of viability of the cells after administration to a subject can be as short as a few hours, e.g., twenty-four hours, to a few days, to as long as several years, or even the life time of the patient, i.e., long-term engraftment. For example, in some aspects described herein, an effective amount of photoreceptor cells or retinal progenitor cells is administered via a systemic route of administration, such as an intraperitoneal or intravenous route.

[000598] The terms "administering," "introducing" and "transplanting" can also be used interchangeably in the context of the placement of at least one of a gRNA, sgRNA, and an endonuclease into a subject, by a method or route that results in at least partial localization of the introduced gRNA, sgRNA, and/or endonuclease at a desired site, such as a site of injury or repair, such that a desired effect(s) is produced. The gRNA, sgRNA, and/or endonuclease can be administered by any appropriate route that results in delivery to a desired location in the subject.

[000599] The terms“individual,”“subject,”“host” and“patient” are used interchangeably herein and refer to any subject for whom diagnosis, treatment or therapy is desired. In some aspects, the subject is a mammal. In some aspects, the subject is a human being.

[000600] When provided prophylactically, progenitor cells described herein can be

administered to a subject in advance of any symptom of autosomal dominant CORD.

Accordingly, the prophylactic administration of a progenitor cell population serves to prevent autosomal dominant CORD.

[000601] A progenitor cell population being administered according to the methods described herein can comprise allogeneic progenitor cells obtained from one or more donors. Such progenitors can be of any cellular or tissue origin, e.g., liver, muscle, cardiac, etc. "Allogeneic" refers to a progenitor cell or biological samples comprising progenitor cells obtained from one or more different donors of the same species, where the genes at one or more loci are not identical. For example, a photoreceptor or retinal progenitor cell population being administered to a subject can be derived from one more unrelated donor subjects, or from one or more non-identical siblings. In some cases, syngeneic progenitor cell populations can be used, such as those obtained from genetically identical animals, or from identical twins. The progenitor cells can be autologous cells; that is, the progenitor cells are obtained or isolated from a subject and administered to the same subject, i.e., the donor and recipient are the same.

[000602] The term "effective amount" refers to the amount of a population of progenitor cells or their progeny needed to prevent or alleviate at least one or more signs or symptoms of autosomal dominant CORD, and relates to a sufficient amount of a composition to provide the desired effect, e.g., to treat a subject having autosomal dominant CORD. The term

"therapeutically effective amount" therefore refers to an amount of progenitor cells or a composition comprising progenitor cells that is sufficient to promote a particular effect when administered to a typical subject, such as one who has or is at risk for autosomal dominant CORD. An effective amount would also include an amount sufficient to prevent or delay the development of a symptom of the disease, alter the course of a symptom of the disease (for example but not limited to, slow the progression of a symptom of the disease), or reverse a symptom of the disease. It is understood that for any given case, an appropriate "effective amount" can be determined by one of ordinary skill in the art using routine experimentation.

[000603] For use in the various aspects described herein, an effective amount of progenitor cells comprises at least 10 ² progenitor cells, at least 5 X 10 ² progenitor cells, at least 10 ³ progenitor cells, at least 5 X 10 ³ progenitor cells, at least 10 ⁴ progenitor cells, at least 5 X 10 ⁴ progenitor cells, at least 10 ⁵ progenitor cells, at least 2 X 10 ⁵ progenitor cells, at least 3 X 10 ⁵ progenitor cells, at least 4 X 10 ⁵ progenitor cells, at least 5 X 10 ⁵ progenitor cells, at least 6 X 10 ⁵ progenitor cells, at least 7 X 10 ⁵ progenitor cells, at least 8 X 10 ⁵ progenitor cells, at least 9 X 10 ⁵ progenitor cells, at least 1 X 10 ⁶ progenitor cells, at least 2 X 10 ⁶ progenitor cells, at least 3 X 10 ⁶ progenitor cells, at least 4 X 10 ⁶ progenitor cells, at least 5 X 10 ⁶ progenitor cells, at least 6 X 10 ⁶ progenitor cells, at least 7 X 10 ⁶ progenitor cells, at least 8 X 10 ⁶ progenitor cells, at least 9 X 10 ⁶ progenitor cells, or multiples thereof. The progenitor cells can be derived from one or more donors, or can be obtained from an autologous source. In some examples described herein, the progenitor cells can be expanded in culture prior to administration to a subject in need thereof.

[000604] Modest and incremental increases in the levels of functional RetGCl protein expressed in cells of patients having autosomal dominant CORD can be beneficial for ameliorating one or more symptoms of the disease, for increasing long-term survival, and/or for reducing side effects associated with other treatments. Upon administration of such cells to human patients, the presence of progenitors that are producing increased levels of functional RetGCl protein is beneficial. In some cases, effective treatment of a subject gives rise to at least about 3%, 5% or 7% functional RetGCl protein relative to total RetGCl in the treated subject.

In some examples, functional RetGCl will be at least about 10% of total RetGCl. In some examples, functional RetGCl protein will be at least about 20% to 30% of total RetGCl protein. Similarly, the introduction of even relatively limited subpopulations of cells having significantly elevated levels of functional RetGCl protein can be beneficial in various patients because in some situations normalized cells will have a selective advantage relative to diseased cells.

However, even modest levels of progenitors with elevated levels of functional RetGC 1 protein can be beneficial for ameliorating one or more aspects of autosomal dominant CORD in patients. In some examples, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90% or more of the photoreceptor cells or retinal progenitor cells in patients to whom such cells are administered are producing increased levels of functional RetGCl protein.

[000605] "Administered" refers to the delivery of a progenitor cell composition into a subject by a method or route that results in at least partial localization of the cell composition at a desired site. A cell composition can be administered by any appropriate route that results in effective treatment in the subject, i.e. administration results in delivery to a desired location in the subject where at least a portion of the composition delivered, i.e. at least 1 x 10 ⁴ cells are delivered to the desired site for a period of time.

[000606] In one aspect of the method, the pharmaceutical composition can be administered via a route such as, but not limited to, enteral (into the intestine), gastroenteral, epidural (into the dura matter), oral (by way of the mouth), transdermal, peridural, intracerebral (into the cerebrum), intracerebroventricular (into the cerebral ventricles), epicutaneous (application onto the skin), intradermal, (into the skin itself), subcutaneous (under the skin), nasal administration (through the nose), intravenous (into a vein), intravenous bolus, intravenous drip, intraarterial (into an artery), intramuscular (into a muscle), intracardiac (into the heart), intraosseous infusion (into the bone marrow), intrathecal (into the spinal canal), intraperitoneal, (infusion or injection into the peritoneum), intravesical infusion, intravitreal, (through the eye), intracavemous injection (into a pathologic cavity) intracavitary (into the base of the penis), intravaginal administration, intrauterine, extra-amniotic administration, transdermal (diffusion through the intact skin for systemic distribution), transmucosal (diffusion through a mucous membrane), transvaginal, insufflation (snorting), sublingual, sublabial, enema, eye drops (onto the conjunctiva), in ear drops, auricular (in or by way of the ear), buccal (directed toward the cheek), conjunctival, cutaneous, dental (to a tooth or teeth), electro-osmosis, endocervical, endosinusial, endotracheal, extracorporeal, hemodialysis, infiltration, interstitial, intra-abdominal, intra- amniotic, intra-articular, intrabiliary, intrabronchial, intrabursal, intracartilaginous (within a cartilage), intracaudal (within the cauda equine), intracistemal (within the cistema magna cerebellomedularis), intracorneal (within the cornea), dental intracomal, intracoronary (within the coronary arteries), intracorporus cavemosum (within the dilatable spaces of the corporus cavernosa of the penis), intradiscal (within a disc), intraductal (within a duct of a gland), intraduodenal (within the duodenum), intradural (within or beneath the dura), intraepidermal (to the epidermis), intraesophageal (to the esophagus), intragastric (within the stomach), intragingival (within the gingivae), intraileal (within the distal portion of the small intestine), intralesional (within or introduced directly to a localized lesion), intraluminal (within a lumen of a tube), intralymphatic (within the lymph), intramedullary (within the marrow cavity of a bone), intrameningeal (within the meninges), intramyocardial (within the myocardium), intraocular (within the eye), intraovarian (within the ovary), intrapericardial (within the pericardium), intrapleural (within the pleura), intraprostatic (within the prostate gland), intrapulmonary (within the lungs or its bronchi), intrasinal (within the nasal or periorbital sinuses), intraspinal (within the vertebral column), intrasynovial (within the synovial cavity of a joint), intratendinous (within a tendon), intratesticular (within the testicle), intrathecal (within the cerebrospinal fluid at any level of the cerebrospinal axis), intrathoracic (within the thorax), intratubular (within the tubules of an organ), intratumor (within a tumor), intratympanic (within the auras media), intravascular (within a vessel or vessels), intraventricular (within a ventricle), iontophoresis (by means of electric current where ions of soluble salts migrate into the tissues of the body), irrigation (to bathe or flush open wounds or body cavities), laryngeal (directly upon the larynx), nasogastric (through the nose and into the stomach), occlusive dressing technique (topical route

administration, which is then covered by a dressing that occludes the area), ophthalmic (to the external eye), oropharyngeal (directly to the mouth and pharynx), parenteral, percutaneous, periarticular, peridural, perineural, periodontal, rectal, respiratory (within the respiratory tract by inhaling orally or nasally for local or systemic effect), retrobulbar (behind the pons or behind the eyeball), intramyocardial (entering the myocardium), soft tissue, subarachnoid, subconjunctival, submucosal, topical, transplacental (through or across the placenta), transtracheal (through the wall of the trachea), transtympanic (across or through the tympanic cavity), ureteral (to the ureter), urethral (to the urethra), vaginal, caudal block, diagnostic, nerve block, biliary perfusion, cardiac perfusion, photopheresis and spinal.

[000607] Modes of administration include injection, infusion, instillation, and/or ingestion. "Injection" includes, without limitation, intravenous, intramuscular, intra-arterial, intrathecal, intraventricular, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, sub capsular, subarachnoid, intraspinal, intracerebro spinal, and intrastemal injection and infusion. In some examples, the route is intravenous. For the delivery of cells, administration by injection or infusion can be made.

[000608] The cells can be administered systemically. The phrases "systemic administration," "administered systemically", "peripheral administration" and "administered peripherally" refer to the administration of a population of progenitor cells other than directly into a target site, tissue, or organ, such that it enters, instead, the subject's circulatory system and, thus, is subject to metabolism and other like processes.

[000609] The efficacy of a treatment comprising a composition for the treatment of autosomal dominant CORD can be determined by the skilled clinician. However, a treatment is considered "effective treatment," if any one or all of the signs or symptoms of, as but one example, levels of functional autosomal dominant CORD are altered in a beneficial manner (e.g., increased by at least 10%), or other clinically accepted symptoms or markers of disease are improved or ameliorated. Efficacy can also be measured by failure of an individual to worsen as assessed by hospitalization or need for medical interventions (e.g., progression of the disease is halted or at least slowed). Methods of measuring these indicators are known to those of skill in the art and/or described herein. Treatment includes any treatment of a disease in an individual or an animal (some non-limiting examples include a human, or a mammal) and includes: (1) inhibiting the disease, e.g., arresting, or slowing the progression of symptoms; or (2) relieving the disease, e.g., causing regression of symptoms; and (3) preventing or reducing the likelihood of the development of symptoms.

[000610] The treatment according to the present disclosure can ameliorate one or more symptoms associated with autosomal dominant CORD by increasing, decreasing or altering the amount of functional RetGCl in the individual. Signs typically associated with autosomal dominant CORD include for example, decreased central vision, color vision defects, photophobia and decreased sensitivity in the central field at early stages, followed by progressive loss in peripheral vision and night blindness at later stages.

[000611] Kits

[000612] The present disclosure provides kits for carrying out the methods described herein. A kit can include one or more of a genome-targeting nucleic acid, a polynucleotide encoding a genome-targeting nucleic acid, a site-directed polypeptide, a polynucleotide encoding a site- directed polypeptide, and/or any nucleic acid or proteinaceous molecule necessary to carry out the aspects of the methods described herein, or any combination thereof.

[000613] A kit can comprise: (1) a vector comprising a nucleotide sequence encoding a genome-targeting nucleic acid, (2) the site-directed polypeptide or a vector comprising a nucleotide sequence encoding the site-directed polypeptide, and (3) a reagent for reconstitution and/or dilution of the vector(s) and or polypeptide. [000614] A kit can comprise: (1) a vector comprising (i) a nucleotide sequence encoding a genome-targeting nucleic acid, and (ii) a nucleotide sequence encoding the site-directed polypeptide; and (2) a reagent for reconstitution and/or dilution of the vector.

[000615] In any of the above kits, the kit can comprise a single-molecule guide genome targeting nucleic acid. In any of the above kits, the kit can comprise a double-molecule genome targeting nucleic acid. In any of the above kits, the kit can comprise two or more double molecule guides or single-molecule guides. The kits can comprise a vector that encodes the nucleic acid targeting nucleic acid.

[000616] In any of the above kits, the kit can further comprise a polynucleotide to be inserted to effect the desired genetic modification.

[000617] Components of a kit can be in separate containers, or combined in a single container.

[000618] Any kit described above can further comprise one or more additional reagents, where such additional reagents are selected from a buffer, a buffer for introducing a polypeptide or polynucleotide into a cell, a wash buffer, a control reagent, a control vector, a control RNA polynucleotide, a reagent for in vitro production of the polypeptide from DNA, adaptors for sequencing and the like. A buffer can be a stabilization buffer, a reconstituting buffer, a diluting buffer, or the like. A kit can also comprise one or more components that can be used to facilitate or enhance the on-target binding or the cleavage of DNA by the endonuclease, or improve the specificity of targeting.

[000619] In addition to the above-mentioned components, a kit can further comprise instructions for using the components of the kit to practice the methods. The instructions for practicing the methods can be recorded on a suitable recording medium. For example, the instructions can be printed on a substrate, such as paper or plastic, etc. The instructions can be present in the kits as a package insert, in the labeling of the container of the kit or components thereof (i.e., associated with the packaging or sub packaging), etc. The instructions can be present as an electronic storage data file present on a suitable computer readable storage medium, e.g. CD-ROM, diskette, flash drive, etc. In some instances, the actual instructions are not present in the kit, but means for obtaining the instructions from a remote source (e.g. via the Internet), can be provided. An example of this case is a kit that comprises a web address where the instructions can be viewed and/or from which the instructions can be downloaded. As with the instructions, this means for obtaining the instructions can be recorded on a suitable substrate. [000620] Additional Therapeutic Approaches

[000621] Gene editing can be conducted using nucleases engineered to target specific sequences. To date there are four major types of nucleases: meganucleases and their derivatives, zinc finger nucleases (ZFNs), transcription activator like effector nucleases (TALENs), and CRISPR-Cas9 nuclease systems. The nuclease platforms vary in difficulty of design, targeting density and mode of action, particularly as the specificity of ZFNs and TALENs is through protein-DNA interactions, while RNA-DNA interactions primarily guide Cas9. Cas9 cleavage also requires an adjacent motif, the PAM, which differs between different CRISPR systems.

Cas9 from Streptococcus pyogenes cleaves using a NGG PAM, CRISPR from Neisseria meningitidis can cleave at sites with PAMs including NNNNGATT, NNNNNGTTT and NNNNGCTT. A number of other Cas9 orthologs target protospacer adjacent to alternative PAMs.

[000622] CRISPR endonucleases, such as Cas9, can be used in the methods of the present disclosure. However, the teachings described herein, such as therapeutic target sites, could be applied to other forms of endonucleases, such as ZFNs, TALENs, HEs, or MegaTALs, or using combinations of nulceases. However, in order to apply the teachings of the present disclosure to such endonucleases, one would need to, among other things, engineer proteins directed to the specific target sites.

[000623] Additional binding domains can be fused to the Cas9 protein to increase specificity. The target sites of these constructs would map to the identified gRNA specified site, but would require additional binding motifs, such as for a zinc finger domain. In the case of Mega-TAL, a meganuclease can be fused to a TALE DNA-binding domain. The meganuclease domain can increase specificity and provide the cleavage. Similarly, inactivated or dead Cas9 (dCas9) can be fused to a cleavage domain and require the sgRNA/Cas9 target site and adjacent binding site for the fused DNA-binding domain. This likely would require some protein engineering of the dCas9, in addition to the catalytic inactivation, to decrease binding without the additional binding site.

[000624] Zinc Finger Nucleases

[000625] Zinc finger nucleases (ZFNs) are modular proteins comprised of an engineered zinc finger DNA binding domain linked to the catalytic domain of the type II endonuclease Fokl. Because Fokl functions only as a dimer, a pair of ZFNs must be engineered to bind to cognate target“half-site” sequences on opposite DNA strands and with precise spacing between them to enable the catalytically active Fokl dimer to form. Upon dimerization of the Fokl domain, which itself has no sequence specificity per se, a DNA double-strand break is generated between the ZFN half-sites as the initiating step in genome editing.

[000626] The DNA binding domain of each ZFN is typically comprised of 3-6 zinc fingers of the abundant Cys2-His2 architecture, with each finger primarily recognizing a triplet of nucleotides on one strand of the target DNA sequence, although cross-strand interaction with a fourth nucleotide also can be important. Alteration of the amino acids of a finger in positions that make key contacts with the DNA alters the sequence specificity of a given finger. Thus, a four-finger zinc finger protein will selectively recognize a 12 bp target sequence, where the target sequence is a composite of the triplet preferences contributed by each finger, although triplet preference can be influenced to varying degrees by neighboring fingers. An important aspect of ZFNs is that they can be readily re-targeted to almost any genomic address simply by modifying individual fingers, although considerable expertise is required to do this well. In most applications of ZFNs, proteins of 4-6 fingers are used, recognizing 12-18 bp respectively.

Hence, a pair of ZFNs will typically recognize a combined target sequence of 24-36 bp, not including the typical 5-7 bp spacer between half-sites. The binding sites can be separated further with larger spacers, including 15-17 bp. A target sequence of this length is likely to be unique in the human genome, assuming repetitive sequences or gene homologs are excluded during the design process. Nevertheless, the ZFN protein-DNA interactions are not absolute in their specificity so off-target binding and cleavage events do occur, either as a heterodimer between the two ZFNs, or as a homodimer of one or the other of the ZFNs. The latter possibility has been effectively eliminated by engineering the dimerization interface of the Fokl domain to create “plus” and“minus” variants, also known as obligate heterodimer variants, which can only dimerize with each other, and not with themselves. Forcing the obligate heterodimer prevents formation of the homodimer. This has greatly enhanced specificity of ZFNs, as well as any other nuclease that adopts these Fokl variants.

[000627] A variety of ZFN-based systems have been described in the art, modifications thereof are regularly reported, and numerous references describe rules and parameters that are used to guide the design of ZFNs; see, e.g., Segal et al., Proc Natl Acad Sci USA 96(6):2758-63 (1999); Dreier B et al., J Mol Biol. 303(4):489-502 (2000); Liu Q et al., J Biol Chem. 277(6):3850-6 (2002); Dreier et al., J Biol Chem 280(42):35588-97 (2005); and Dreier et al., J Biol Chem.

276(31):29466-78 (2001). [000628] Transcription Activator-Like Effector Nucleases (TALENs)

[000629] Transcription Activator-Like Effector Nucleases (TALENs) represent another format of modular nucleases whereby, as with ZFNs, an engineered DNA binding domain is linked to the Fokl nuclease domain, and a pair of TALENs operates in tandem to achieve targeted DNA cleavage. The major difference from ZFNs is the nature of the DNA binding domain and the associated target DNA sequence recognition properties. The TALEN DNA binding domain derives from TALE proteins, which were originally described in the plant bacterial pathogen Xanthomonas sp. TALEs are comprised of tandem arrays of 33-35 amino acid repeats, with each repeat recognizing a single base pair in the target DNA sequence that is typically up to 20 bp in length, giving a total target sequence length of up to 40 bp. Nucleotide specificity of each repeat is determined by the repeat variable diresidue (RVD), which includes just two amino acids at positions 12 and 13. The bases guanine, adenine, cytosine and thymine are predominantly recognized by the four RVDs: Asn-Asn, Asn-Ile, His-Asp and Asn-Gly, respectively. This constitutes a much simpler recognition code than for zinc fingers, and thus represents an advantage over the latter for nuclease design. Nevertheless, as with ZFNs, the protein-DNA interactions of TALENs are not absolute in their specificity, and TALENs have also benefitted from the use of obligate heterodimer variants of the Fokl domain to reduce off-target activity.

[000630] Additional variants of the Fokl domain have been created that are deactivated in their catalytic function. If one half of either a TALEN or a ZFN pair contains an inactive Fokl domain, then only single-strand DNA cleavage (nicking) will occur at the target site, rather than a DSB. The outcome is comparable to the use of CRISPR/Cas9/Cpfl“nickase” mutants in which one of the Cas9 cleavage domains has been deactivated. DNA nicks can be used to drive genome editing by HDR, but at lower efficiency than with a DSB. The main benefit is that off- target nicks are quickly and accurately repaired, unlike the DSB, which is prone to NHEJ- mediated mis-repair.

[000631] A variety of TALEN-based systems have been described in the art, and modifications thereof are regularly reported; see, e.g., Boch, Science 326(5959): 1509-12 (2009); Mak et ah, Science 335(6069):7l6-9 (2012); and Moscou et ah, Science 326(5959): 1501 (2009). The use of TALENs based on the "Golden Gate" platform, or cloning scheme, has been described by multiple groups; see, e.g., Cermak et ah, Nucleic Acids Res. 39(l2):e82 (2011); Li et ak, Nucleic Acids Res. 39(l4):6315-25(2011); Weber et ak, PLoS One. 6(2): e 16765 (2011); Wang et ak, J Genet Genomics 4l(6):339-47, Epub 2014 May 17 (2014); and Cermak T et ak, Methods Mol Biol. 1239: 133-59 (2015). [000632] Homing Endonucleases

[000633] Homing endonucleases (HEs) are sequence-specific endonucleases that have long recognition sequences (14-44 base pairs) and cleave DNA with high specificity - often at sites unique in the genome. There are at least six known families of HEs as classified by their structure, including LAGLIDADG (SEQ ID NO: 5271), GIY-YIG, His-Cis box, H-N-H, PD- (D/E)xK, and Vsr-like that are derived from a broad range of hosts, including eukarya, protists, bacteria, archaea, cyanobacteria and phage. As with ZFNs and TALENs, HEs can be used to create a DSB at a target locus as the initial step in genome editing. In addition, some natural and engineered HEs cut only a single strand of DNA, thereby functioning as site-specific nickases. The large target sequence of HEs and the specificity that they offer have made them attractive candidates to create site-specific DSBs.

[000634] A variety of HE-based systems have been described in the art, and modifications thereof are regularly reported; see, e.g., the reviews by Steentoft et ah, Glycobiology 24(8):663- 80 (2014); Belfort and Bonocora, Methods Mol Biol. 1123: 1-26 (2014); Hafez and Hausner, Genome 55(8):553-69 (2012).

[000635] MegaTAL / Tev-mTALEN / MegaTev

[000636] As further examples of hybrid nucleases, the MegaTAL platform and Tev-mTALEN platform use a fusion of TALE DNA binding domains and catalytically active HEs, taking advantage of both the tunable DNA binding and specificity of the TALE, as well as the cleavage sequence specificity of the HE; see, e.g., Boissel et ak, NAR 42: 2591-2601 (2014); Kleinstiver et ak, G3 4: 1155-65 (2014); and Boissel and Scharenberg, Methods Mol. Biol. 1239: 171-96 (2015).

[000637] In a further variation, the MegaTev architecture is the fusion of a meganuclease (Mega) with the nuclease domain derived from the GIY-YIG homing endonuclease I-Tevl (Tev). The two active sites are positioned ~30 bp apart on a DNA substrate and generate two DSBs with non-compatible cohesive ends; see, e.g., Wolfs et ak, NAR 42, 8816-29 (2014). It is anticipated that other combinations of existing nuclease-based approaches will evolve and be useful in achieving the targeted genome modifications described herein.

[000638] dCas9-FokI or dCpfl-Fokl and Other Nucleases

[000639] Combining the structural and functional properties of the nuclease platforms described above offers a further approach to genome editing that can potentially overcome some of the inherent deficiencies. As an example, the CRISPR genome editing system typically uses a single Cas9 endonuclease to create a DSB. The specificity of targeting is driven by a 20 or 24 nucleotide sequence in the guide RNA that undergoes Watson-Crick base-pairing with the target DNA (plus an additional 2 bases in the adjacent NAG or NGG PAM sequence in the case of Cas9 from S. pyogenes). Such a sequence is long enough to be unique in the human genome, however, the specificity of the RNA/DNA interaction is not absolute, with significant promiscuity sometimes tolerated, particularly in the 5’ half of the target sequence, effectively reducing the number of bases that drive specificity. One solution to this has been to completely deactivate the Cas9 or Cpfl catalytic function - retaining only the RNA-guided DNA binding function - and instead fusing a Fokl domain to the deactivated Cas9; see, e.g., Tsai et ak, Nature Biotech 32: 569-76 (2014); and Guilinger et ak, Nature Biotech. 32: 577-82 (2014). Because Fokl must dimerize to become catalytically active, two guide RNAs are required to tether two Fokl fusions in close proximity to form the dimer and cleave DNA. This essentially doubles the number of bases in the combined target sites, thereby increasing the stringency of targeting by CRISPR-based systems.

[000640] As further example, fusion of the TALE DNA binding domain to a catalytically active HE, such as I-Tevl, takes advantage of both the tunable DNA binding and specificity of the TALE, as well as the cleavage sequence specificity of I-Tevl, with the expectation that off- target cleavage can be further reduced.

[000641] Methods and Compositions of the Invention

[000642] Accordingly, the present disclosure relates in particular to the following non-limiting inventions:

[000643] In a first method, Method 1, the present disclosure provides a method for editing a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the GUCY2D gene or other DNA sequences that encode regulatory elements of the GUCY2D gene that results in a deletion, insertion, or correction thereby creating an edited human cell.

[000644] In another method, Method 2, the present disclosure provides a method for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H, R838C, or R838S mutation in a GUCY2D gene that results in a deletion, insertion, or correction thereby creating an edited human cell.

[000645] In another method, Method 3, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD, the method comprising: editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a cell of the patient. [000646] In another method, Method 4, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 3, wherein the editing comprises: introducing into the cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H, R838C, or R838S mutation in a GUCY2D gene that results in a deletion, insertion, or correction and results in restoration of RetGCl protein activity.

[000647] In another method, Method 5, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 1-2 or 4, wherein the one or more DNA endonucleases is a Casl, CaslB, Cas2, Cas3, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csnl and Csxl2), Casl 00, Csyl, Csy2, Csy3, Csel, Cse2, Cscl, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmrl, Cmr3, Cmr4, Cmr5, Cmr6, Csbl, Csb2, Csb3, Csxl7, Csxl4, CsxlO, Csxl6, CsaX, Csx3, Csxl, Csxl5, Csfl, Csf2, Csf3, Csf4, or Cpfl endonuclease; a homolog thereof, a recombination of the naturally occurring molecule thereof, codon-optimized thereof, or modified versions thereof, and combinations thereof.

[000648] In another method, Method 6, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 5, wherein the method comprises introducing into the cell one or more polynucleotides encoding the one or more DNA endonucleases.

[000649] In another method, Method 7, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 5, wherein the method comprises introducing into the cell one or more RNAs encoding the one or more DNA endonucleases.

[000650] In another method, Method 8, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 6 or 7, wherein the one or more polynucleotides or one or more RNAs is one or more modified polynucleotides or one or more modified RNAs.

[000651] In another method, Method 9, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 5, wherein the DNA endonuclease is one or more proteins or polypeptides.

[000652] In another method, Method 10, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 1-9, wherein the method further comprises: introducing into the cell one or more gRNAs. [000653] In another method, Method 11, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 10, wherein the one or more gRNAs are sgRNAs.

[000654] In another method, Method 12, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 10-11, wherein the one or more gRNAs or one or more sgRNAs is one or more modified gRNAs or one or more modified sgRNAs.

[000655] In another method, Method 13, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 9-11, wherein the one or more DNA endonucleases is pre-complexed with one or more gRNAs or one or more sgRNAs.

[000656] In another method, Method 14, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 1-13, further comprising: introducing into the cell a polynucleotide donor template comprising at least a portion of the wild-type GUCY2D gene, or cDNA.

[000657] In another method, Method 15, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 14, wherein the at least a portion of the wild-type GUCY2D gene or cDNA is exon 1, exon 2, exon 3, exon 4, exon 5, exon 6, exon 7, exon 8, exon 9, exon 10, exon 11, exon 12, exon 13, exon 14, exon 15, exon 16, exon 17, exon 18, exon 19, exon 20, intronic regions, fragments or combinations thereof, or the entire GUCY2D gene or cDNA.

[000658] In another method, Method 16, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 14-15, wherein the donor template is either a single or double stranded polynucleotide.

[000659] In another method, Method 17, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 14-15, wherein the donor template has homologous arms to the 17r13.1 region.

[000660] In another method, Method 18, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 2 or 4, further comprising: introducing into the cell one gRNA and a polynucleotide donor template comprising at least a portion of the wild-type GUCY2D gene; wherein the one or more DNA endonucleases is one or more Cas9 or Cpfl endonucleases that effect one SSB or DSB at a locus located within or near the R838H, R838C, or R838S mutation in a GUCY2D gene that facilitates insertion of a new sequence from the polynucleotide donor template into the chromosomal DNA at the locus that results in a insertion or correction of the R838H, R838C, or R838S mutation in a GUCY2D gene; and wherein the gRNA comprises a spacer sequence that is complementary to a segment of the locus located within or near the R838H, R838C, or R838S mutation in a GUCY2D gene.

[000661] In another method, Method 19, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 2 or 4, further comprising: introducing into the cell one or more gRNAs and a polynucleotide donor template comprising at least a portion of the wild-type GUCY2D gene; wherein the one or more DNA endonucleases is one or more Cas9 or Cpfl endonucleases that effect a pair of SSBs or DSBs, the first at a 5’ locus and the second at a 3’ locus, within or near the R838H, R838C, or R838S mutation in a GUCY2D gene that facilitates insertion of a new sequence from the polynucleotide donor template into the chromosomal DNA between the 5’ locus and the 3’ locus that results in a insertion or correction of the chromosomal DNA between the 5’ locus and the 3’ locus within or near the R838H, R838C, or R838S mutation in a GUCY2D gene; and wherein the first gRNA comprises a spacer sequence that is complementary to a segment of the 5' locus and the second gRNA comprises a spacer sequence that is complementary to a segment of the 3' locus.

[000662] In another method, Method 20, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-19, wherein the one or more gRNAs are one or more sgRNAs.

[000663] In another method, Method 21, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-20, wherein the one or more gRNAs or one or more sgRNAs is one or more modified gRNAs or one or more modified sgRNAs.

[000664] In another method, Method 22, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-21, wherein the one or more DNA endonucleases is pre-complexed with one or more gRNAs or one or more sgRNAs.

[000665] In another method, Method 23, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-22, wherein the at least a portion of the wild-type GUCY2D gene or cDNA is exon 1, exon 2, exon 3, exon 4, exon 5, exon 6, exon 7, exon 8, exon 9, exon 10, exon 11, exon 12, exon 13, exon 14, exon 15, exon 16, exon 17, exon 18, exon 19, exon 20, intronic regions, fragments or combinations thereof, or the entire GUCY2D gene or cDNA. [000666] In another method, Method 24, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-23, wherein the donor template is either a single or double stranded polynucleotide.

[000667] In another method, Method 25, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-24, wherein the donor template has homologous arms to the 17r13.1 region.

[000668] In another method, Method 26, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-25, wherein the SSB or DSB are in the first exon, second exon, third exon, fourth exon, fifth exon, sixth exon, seventh exon, eighth exon, ninth exon, tenth exon, eleventh exon, twelfth exon, thirteenth exon, fourteenth exon, fifteenth exon, sixteenth exon, seventeenth exon, eighteenth exon, nineteenth exon, twentieth exon, or combinations thereof of the GUCY2D gene.

[000669] In another method, Method 27, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 10-13 or 20-22, wherein the gRNA or sgRNA is directed to one or more pathological variant: R838H, R838C, or R838S.

[000670] In another method, Method 28, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 1-2 or 4-27, wherein the insertion or correction is by HDR.

[000671] In another method, Method 29, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-19, wherein the donor template has homologous arms to a pathological variant R838H, R838C, or R838S.

[000672] In another method, Method 30, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 2 or 4, further comprising: introducing into the cell two gRNAs and a polynucleotide donor template comprising at least a portion of the wild-type GUCY2D gene; wherein the one or more DNA endonucleases is one or more Cas9 or Cpfl endonucleases that effect a pair of DSBs, the first at a 5’ DSB locus and the second at a 3’ DSB locus, within or near the R838H, R838C, or R838S mutation in a GUCY2D gene that causes a deletion of the chromosomal DNA between the 5’ DSB locus and the 3’ DSB locus that results in a deletion of the chromosomal DNA between the 5’ DSB locus and the 3’ DSB locus within or near the R838H, R838C, or R838S mutation in a GUCY2D gene; and wherein the first guide RNA comprises a spacer sequence that is complementary to a segment of the 5' DSB locus and the second guide RNA comprises a spacer sequence that is complementary to a segment of the 3' DSB locus.

[000673] In another method, Method 31, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 30, wherein the two gRNAs are two sgRNAs.

[000674] In another method, Method 32, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 30-31, wherein the two gRNAs or two sgRNAs are two modified gRNAs or two modified sgRNAs.

[000675] In another method, Method 33, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 30-32, wherein the one or more DNA endonucleases is pre-complexed with two gRNAs or two sgRNAs.

[000676] In another method, Method 34, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 30-33, wherein both the 5’ DSB and 3’ DSB are in or near either the first exon, first intron, second exon, second intron, third exon, third intron, fourth exon, fourth intron, fifth exon, fifth intron, sixth exon, sixth intron, seventh exon, seventh intron, eighth exon, eighth intron, ninth exon, ninth intron, tenth exon, tenth intron, eleventh exon, eleventh intron, twelfth exon, twelfth intron, thirteenth exon, thirteenth intron, fourteenth exon, fourteenth intron, fifteenth exon, fifteenth intron, sixteenth exon, sixteenth intron, seventeenth exon, seventeenth intron, eighteenth exon, eighteenth intron, nineteenth exon, nineteenth intron, twentieth exon, or combinations thereof, of the GUCY2D gene.

[000677] In another method, Method 35, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 30-34, wherein the deletion is a deletion of 1 kb or less.

[000678] In another method, Method 36, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-19 and 30, wherein the Cas9 or Cpfl mRNA, gRNA, and donor template are either each formulated into separate lipid nanoparticles or all co-formulated into a lipid nanoparticle.

[000679] In another method, Method 37, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-19 and 30, wherein the Cas9 or Cpfl mRNA, gRNA, and donor template are either each formulated into separate AAV vectors or all co-formulated into an AAV vector. [000680] In another method, Method 38, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-19 and 30, wherein the Cas9 or Cpfl mRNA is formulated into a lipid nanoparticle, and both the gRNA and donor template are delivered to the cell by an AAV vector.

[000681] In another method, Method 39, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 18-19 and 30, wherein the Cas9 or Cpfl mRNA is formulated into a lipid nanoparticle, and the gRNA is delivered to the cell by electroporation and donor template is delivered to the cell by an AAV vector.

[000682] In another method, Method 40, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 37-39, wherein the AAV vector is a self-inactivating AAV vector.

[000683] In another method, Method 41, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 1-40, wherein the GUCY2D gene is located on Chromosome 17: 8,002,594 to 8,020,339 (Genome Reference Consortium - GRCh38/hg38).

[000684] In another method, Method 42, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 2 or 4-41, wherein the restoration of RetGCl protein activity is compared to wild-type or normal RetGCl protein activity.

[000685] In another method, Method 43, the present disclosure provides a method for editing a GUCY2D gene in a human cell as provided in Methods 1-2, wherein the human cell is a photoreceptor cell or retinal progenitor cell.

[000686] In another method, Method 44, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Methods 3-42, wherein the cell is a photoreceptor cell or retinal progenitor cell.

[000687] In another method, Method 45, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 14, wherein the polynucleotide donor template comprises exon 1 of GUCY2D and is up to 5 KB.

[000688] In another method, Method 46, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 45, wherein the polynucleotide donor template is delivered by AAV. [000689] In another method, Method 47, the present disclosure provides a method for editing a R838H mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H mutation in a GUCY2D gene that results in a deletion, insertion, correction, or modulation of expression or function of the R838H mutation thereby creating an edited human cell.

[000690] In another method, Method 48, the present disclosure provides a method for editing a R838C mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838C mutation in a GUCY2D gene that results in a deletion, insertion, correction, or modulation of expression or function of the R838C mutation thereby creating an edited human cell.

[000691] In another method, Method 49, the present disclosure provides a method for editing a R838S mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838S mutation in a GUCY2D gene that results in a deletion, insertion, correction, or modulation of expression or function of the R838S mutation thereby creating an edited human cell.

[000692] In another method, Method 50, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD, the method comprising: editing a R838H mutation in a GUCY2D gene in a cell of the patient.

[000693] In another method, Method 51, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD, the method comprising: editing a R838C mutation in a GUCY2D gene in a cell of the patient.

[000694] In another method, Method 52, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD, the method comprising: editing a R838S mutation in a GUCY2D gene in a cell of the patient.

[000695] In another method, Method 53, the present disclosure provides a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5285.

[000696] In another method, Method 54, the present disclosure provides a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5286. [000697] In another method, Method 55, the present disclosure provides a method for editing an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5398.

[000698] In another method, Method 56, the present disclosure provides a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5464.

[000699] In another method, Method 57, the present disclosure provides a method for editing an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5465.

[000700] In another method, Method 58, the present disclosure provides a method for editing an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5466.

[000701] In another method, Method 59, the present disclosure provides a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5285 to the patient.

[000702] In another method, Method 60, the present disclosure provides a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5286 to the patient.

[000703] In another method, Method 61 , the present disclosure provides a method for treating a patient with an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5398 to the patient.

[000704] In another method, Method 62, the present disclosure provides a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5464 to the patient.

[000705] In another method, Method 63, the present disclosure provides a method for treating a patient with an R838H mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5465 to the patient.

[000706] In another method, Method 64, the present disclosure provides a method for treating a patient with an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering a gRNA or sgRNA comprising SEQ ID NO: 5466 to the patient.

[000707] In another method, Method 65, the present disclosure provides a method for editing an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering the self-inactivating CRISPR-Cas system of any of Self-inactivating CRISPR-Cas systems 1-35.

[000708] In another method, Method 66, the present disclosure provides a method for treating a patient with an R838H mutation or R838C mutation within a GUCY2D gene, the method comprising administering the self-inactivating CRISPR-Cas system of any of Self-inactivating CRISPR-Cas systems 1-35.

[000709] In another method, Method 67, the present disclosure provides a method of controlling Cas9 expression in a cell comprising: contacting the cell with the the self-inactivating CRISPR-Cas system of any of Self-inactivating CRISPR-Cas systems 1-35.

[000710] In another method, Method 68, the present disclosure provides a method for editing a GUCY2D gene in a human cell as provided in Method 1, wherein the human cell has defective activity and the edited human cell expresses a functional GUCY2D.

[000711] In another method, Method 69, the present disclosure provides a method for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell as provided in Method 2, wherein the human cell has defective activity and the edited human cell expresses a functional GUCY2D.

[000712] In another method, Method 70, the present disclosure provides a method for editing a R838H mutation in a GUCY2D gene in a human cell as provided in Method 47, wherein the human cell has defective activity and the edited human cell expresses a functional GUCY2D.

[000713] In another method, Method 71, the present disclosure provides a method for editing a R838C mutation in a GUCY2D gene in a human cell as provided in Method 48, wherein the human cell has defective activity and the edited human cell expresses a functional GUCY2D.

[000714] In another method, Method 72, the present disclosure provides a method for editing a R838S mutation in a GUCY2D gene in a human cell as provided in Method 49, wherein the human cell has defective activity and the edited human cell expresses a functional GUCY2D.

[000715] In another method, Method 73, the present disclosure provides a method for editing a GUCY2D gene in a human cell as provided in Method 1, wherein the deletion, insertion, or correction results in a modulation of expression or function of the GUCY2D gene.

[000716] In another method, Method 74, the present disclosure provides a method for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell as provided in Method 2, wherein the deletion, insertion, or correction results in a modulation of expression or function of the GUCY2D gene. [000717] In another method, Method 75, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 4, wherein the deletion, insertion, or correction results in a modulation of expression or function of the

GUCY2D gene and results in restoration of retinal membrane guanylate cyclase-l (RetGCl) protein activity.

[000718] In another method, Method 76, the present disclosure provides an in vivo method for treating a patient with autosomal dominant CORD as provided in Method 3, wherein the editing comprises: introducing into the cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H, R838C, or R838S mutation in a GUCY2D gene that results in a modulation of expression or function of the GUCY2D gene and results in restoration of retinal membrane guanylate cyclase-l (RetGCl) protein activity.

[000719] In another method, Method 77, the present disclosure provides a method for editing a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more deoxyribonucleic acid (DNA) endonucleases to effect one or more single-strand breaks (SSBs) or double-strand breaks (DSBs) within or near the GUCY2D gene or other DNA sequences that encode regulatory elements of the GUCY2D gene that results in a modulation of expression or function of the GUCY2D gene thereby creating an edited human cell.

[000720] In another method, Method 78, the present disclosure provides a method for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H, R838C, or R838S mutation in a GUCY2D gene that results in a modulation of expression or function of the GUCY2D gene thereby creating an edited human cell.

[000721] In another method, Method 79, the present disclosure provides a method for editing a R838H mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H mutation in a GUCY2D gene that results in a deletion, insertion, or correction thereby creating an edited human cell.

[000722] In another method, Method 80, the present disclosure provides a method for editing a R838H mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838H mutation in a GUCY2D gene that results in a modulation of expression or function thereby creating an edited human cell. [000723] In another method, Method 81, the present disclosure provides a method for editing a R838C mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838C mutation in a GUCY2D gene that results in a deletion, insertion, or correction thereby creating an edited human cell.

[000724] In another method, Method 82, the present disclosure provides a method for editing a R838C mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838C mutation in a GUCY2D gene that results in a modulation of expression or function thereby creating an edited human cell.

[000725] In another method, Method 83, the present disclosure provides a method for editing a R838S mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838S mutation in a GUCY2D gene that results in a deletion, insertion, or correction thereby creating an edited human cell.

[000726] In another method, Method 84, the present disclosure provides a method for editing a R838S mutation in a GUCY2D gene in a human cell, the method comprising: introducing into the human cell one or more DNA endonucleases to effect one or more SSBs or DSBs within or near the R838S mutation in a GUCY2D gene that results in a modulation of expression or function thereby creating an edited human cell.

[000727] In a first composition, Composition 1, the present disclosure provides one or more gRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398- 5409, and 5434-5443 of the Sequence Listing.

[000728] In another composition, Composition 2, the present disclosure provides the one or more gRNAs of Composition 1, wherein the one or more gRNAs are one or more sgRNAs.

[000729] In another composition, Composition 3, the present disclosure provides the one or more gRNAs of Compositions 1 or 2, wherein the one or more gRNAs or one or more sgRNAs is one or more modified gRNAs or one or more modified sgRNAs.

[000730] In another composition, Composition 4, the present disclosure provides the one or more gRNAs of Compositions 1-3, wherein the cell is a photoreceptor cell, retinal progenitor cell, or induced pluripotent stem cell (iPSC). [000731] In another composition, Composition 5, the present disclosure provides one or more gRNAs for editing a R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5293, 5398-5409, and 5434-5443 of the Sequence Listing.

[000732] In another composition, Composition 6, the present disclosure provides one or more gRNAs for editing a R838C mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5294-5303 and 5398-5409 of the Sequence Listing.

[000733] In another composition, Composition 7, the present disclosure provides one or more gRNAs for editing a R838S mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5304-5313 and 5434-5443 of the Sequence Listing.

[000734] In another composition, Composition 8, the present disclosure provides a gRNA for editing a R838H or R838C mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the gRNA comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398-5409 of the Sequence Listing.

[000735] In another composition, Composition 9, the present disclosure provides the gRNA of Composition 8, wherein the gRNA is a sgRNA.

[000736] In another composition, Composition 10, the present disclosure provides the gRNA or sgRNA of Compositions 8 or 9, wherein the gRNA or sgRNA is a modified gRNA or modified sgRNA.

[000737] In another composition, Composition 11, the present disclosure provides the gRNA or sgRNA of Compositions 8-10, wherein the cell is a photoreceptor cell, retinal progenitor cell, or induced pluripotent stem cell (iPSC).

[000738] In another composition, Composition 12, the present disclosure provides a gRNA for editing a R838H or R838S mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the gRNA comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5434-5443 of the Sequence Listing.

[000739] In another composition, Composition 13, the present disclosure provides the gRNA of Composition 12, wherein the gRNA is a sgRNA. [000740] In another composition, Composition 14, the present disclosure provides the gRNA or sgRNA of Compositions 12 or 13, wherein the gRNA or sgRNA is a modified gRNA or modified sgRNA.

[000741] In another composition, Composition 15, the present disclosure provides the gRNA or sgRNA of Compositions 12-14, wherein the cell is a photoreceptor cell, retinal progenitor cell, or induced pluripotent stem cell (iPSC).

[000742] In another composition, Composition 16, the present disclosure provides a single molecule guide RNA (sgRNA) for editing a R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the sgRNA comprising the nucleic acid sequence of SEQ ID NO: 5285.

[000743] In another composition, Composition 17, the present disclosure provides a single molecule guide RNA (sgRNA) for editing a R838H or R838C mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the sgRNA comprising the nucleic acid sequence of SEQ ID NO: 5398.

[000744] In another composition, Composition 18, the present disclosure provides a single molecule guide RNA (sgRNA) for editing a R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the sgRNA comprising the nucleic acid sequence of SEQ ID NO: 5286.

[000745] In another composition, Composition 19, the present disclosure provides a single molecule guide RNA (sgRNA) for editing a R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the sgRNA comprising the nucleic acid sequence of SEQ ID NO: 5464.

[000746] In another composition, Composition 20, the present disclosure provides a single molecule guide RNA (sgRNA) for editing a R838H mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the sgRNA comprising the nucleic acid sequence of SEQ ID NO: 5465.

[000747] In another composition, Composition 21, the present disclosure provides a single molecule guide RNA (sgRNA) for editing a R838H or R838C mutation in a GUCY2D gene in a cell from a patient with autosomal dominant CORD, the sgRNA comprising the nucleic acid sequence of SEQ ID NO: 5466.

[000748] In another composition, Composition 22, the present disclosure provides one or more gRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 of the Sequence Listing.

[000749] In a first therapeutic, Therapeutic 1, the present disclosure provides a therapeutic for treating a patient with autosomal dominant Cone-Rod Dystrophy, the therapeutic comprising at least one or more gRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 of the Sequence Listing.

[000750] In another therapeutic, Therapeutic 2, the present disclosure provides the therapeutic of Therapeutic 2, wherein the one or more gRNAs are one or more sgRNAs.

[000751] In another therapeutic, Therapeutic 3, the present disclosure provides the therapeutic of Therapeutics 1 or 2, wherein the one or more gRNAs or one or more sgRNAs is one or more modified gRNAs or one or more modified sgRNAs.

[000752] In another therapeutic, Therapeutic 4, the present disclosure provides a therapeutic for treating a patient with autosomal dominant CORD, the therapeutic formed by a method comprising: introducing one or more DNA endonucleases; introducing one or more gRNA or one or more sgRNA for editing a R838H, R838C, or R838S mutation in a GUCY2D gene; and optionally introducing one or more donor template; wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 of the Sequence Listing.

[000753] In another therapeutic, Therapeutic 5, the present disclosure provides a therapeutic comprising at least one or more gRNAs for editing a R838H mutation in a GUCY2D gene, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5293, 5398-5409, and 5434-5443 of the Sequence Listing.

[000754] In another therapeutic, Therapeutic 6, the present disclosure provides a therapeutic comprising at least one or more gRNAs for editing a R838C mutation in a GUCY2D gene, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5294-5303 and 5398-5409 of the Sequence Listing.

[000755] In another therapeutic, Therapeutic 7, the present disclosure provides a therapeutic comprising at least one or more gRNAs for editing a R838S mutation in a GUCY2D gene, the one or more gRNAs comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5304-5313 and 5434-5443 of the Sequence Listing. [000756] In another therapeutic, Therapeutic 8, the present disclosure provides a therapeutic for treating a patient with autosomal dominant CORD, formed by a method comprising: introducing one or more DNA endonucleases; introducing one or more gRNA or one or more sgRNA for editing a R838H mutation in a GUCY2D gene; and optionally introducing one or more donor template; wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5293, 5398-5409, and 5434-5443 of the Sequence Listing.

[000757] In another therapeutic, Therapeutic 9, the present disclosure provides a therapeutic for treating a patient with autosomal dominant CORD, formed by a method comprising: introducing one or more DNA endonucleases; introducing one or more gRNA or one or more sgRNA for editing a R838C mutation in a GUCY2D gene; and optionally introducing one or more donor template; wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5294-5303 and 5398-5409 of the Sequence Listing.

[000758] In another therapeutic, Therapeutic 10, the present disclosure provides a therapeutic for treating a patient with autosomal dominant CORD, formed by a method comprising:

introducing one or more DNA endonucleases; introducing one or more gRNA or one or more sgRNA for editing a R838S mutation in a GUCY2D gene; and optionally introducing one or more donor template; wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5304-5313 and 5434-5443 of the Sequence Listing.

[000759] In another therapeutic, Therapeutic 11, the present disclosure provides a therapeutic comprising a gRNA for editing a R838H or R838C mutation in a GUCY2D gene, the gRNA comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398-5409 of the Sequence Listing.

[000760] In another therapeutic, Therapeutic 12, the present disclosure provides the therapeutic of Therapeutic 11, wherein the gRNA is a sgRNA.

[000761] In another therapeutic, Therapeutic 13, the present disclosure provides the therapeutic of Therapeutics 11 or 12, wherein the gRNA or sgRNA is a modified gRNA or modified sgRNA.

[000762] In another therapeutic, Therapeutic 14, the present disclosure provides a therapeutic for treating a patient with autosomal dominant CORD, formed by the method comprising:

introducing one or more DNA endonucleases; introducing a gRNA or sgRNA for editing a R838H or R838C mutation in a GUCY2D gene; and introducing one or more donor template; wherein the gRNA or sgRNA comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398-5409 of the Sequence Listing.

[000763] In another therapeutic, Therapeutic 15, the present disclosure provides a therapeutic comprising a gRNA for editing a R838H or R838S mutation in a GUCY2D gene, the gRNA comprising a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5434-5443 of the Sequence Listing.

[000764] In another therapeutic, Therapeutic 16, the present disclosure provides the therapeutic of Therapeutic 15, wherein the gRNA is a sgRNA.

[000765] In another therapeutic, Therapeutic 17, the present disclosure provides the therapeutic of Therapeutics 15 or 16, wherein the gRNA or sgRNA is a modified gRNA or modified sgRNA.

[000766] In another therapeutic, Therapeutic 18, the present disclosure provides a therapeutic for treating a patient with autosomal dominant CORD, formed by the method comprising:

introducing one or more DNA endonucleases; introducing a gRNA or sgRNA for editing a R838H or R838S mutation in a GUCY2D gene; and introducing one or more donor template; wherein the gRNA or sgRNA comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5434-5443 of the Sequence Listing.

[000767] In another therapeutic, Therapeutic 19, the present disclosure provides a therapeutic comprising the self-inactivating CRISPR-Cas system of any of Self-inactivating CRISPR-Cas systems 1-35.

[000768] In another therapeutic, Therapeutic 20, the present disclosure provides the therapeutic of Therapeutic 19, wherein the therapeutic is sterile.

[000769] In a first kit, Kit 1, the present disclosure provides a kit for treating a patient with autosomal dominant CORD in vivo, the kit comprising one or more gRNAs or sgRNAs for editing a R838H, R838C, or R838S mutation in a GUCY2D gene wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443 of the Sequence Listing; one or more DNA endonucleases; and optionally, one or more donor template.

[000770] In another kit, Kit 2, the present disclosure provides the kit of Kit 1, wherein the one or more DNA endonucleases is a Casl, CaslB, Cas2, Cas3, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csnl and Csxl2), CaslOO, Csyl, Csy2, Csy3, Csel, Cse2, Cscl, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmrl, Cmr3, Cmr4, Cmr5, Cmr6, Csbl, Csb2, Csb3, Csxl7, Csxl4, CsxlO, Csxl6, CsaX, Csx3, Csxl, Csxl5, Csfl, Csf2, Csf3, Csf4, or Cpfl endonuclease; a homolog thereof, a recombination of the naturally occurring molecule thereof, codon-optimized thereof, or modified versions thereof, and combinations thereof.

[000771] In another kit, Kit 3, the present disclosure provides the kit of Kits 1 or 2, comprising one or more donor template.

[000772] In another kit, Kit 4, the present disclosure provides the kit of Kit 3, wherein the donor template has homologous arms to the 17r13.1 region.

[000773] In another kit, Kit 5, the present disclosure provides the kit of Kit 3, wherein the donor template has homologous arms to a pathological variant R838H, R838C, or R838S.

[000774] In another kit, Kit 6, the present disclosure provides a kit for treating a patient with autosomal dominant CORD in vivo, the kit comprising one or more gRNAs or sgRNAs for editing a R838H mutation in a GUCY2D gene wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5282-5293, 5398-5409, and 5434-5443 of the Sequence Listing; one or more DNA endonucleases; and optionally, one or more donor template.

[000775] In another kit, Kit 7, the present disclosure provides a kit for treating a patient with autosomal dominant CORD in vivo, the kit comprising one or more gRNAs or sgRNAs for editing a R838C mutation in a GUCY2D gene wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5294-5303 and 5398-5409 of the Sequence Listing; one or more DNA endonucleases; and optionally, one or more donor template.

[000776] In another kit, Kit 8, the present disclosure provides a kit for treating a patient with autosomal dominant CORD in vivo, the kit comprising one or more gRNAs or sgRNAs for editing a R838S mutation in a GUCY2D gene wherein the one or more gRNAs or sgRNAs comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5304-5313 and 5434-5443 of the Sequence Listing; one or more DNA endonucleases; and optionally, one or more donor template.

[000777] In another kit, Kit 9, the present disclosure provides a kit for treating a patient with autosomal dominant CORD in vivo, the kit comprising a gRNA or sgRNA for editing a R838H or R838C mutation in a GUCY2D gene, wherein the gRNA or sgRNA comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5398- 5409 of the Sequence Listing; one or more DNA endonucleases; and optionally, one or more donor template. [000778] In another kit, Kit 10, the present disclosure provides the kit of Kit 9, wherein the one or more DNA endonucleases is a Casl, CaslB, Cas2, Cas3, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csnl and Csxl2), CaslOO, Csyl, Csy2, Csy3, Cse l, Cse2, Cscl, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmrl, Cmr3, Cmr4, Cmr5, Cmr6, Csbl, Csb2, Csb3, Csxl7, Csxl4, CsxlO, Csxl6, CsaX, Csx3, Csxl, Csxl5, Csfl, Csf2, Csf3, Csf4, or Cpfl endonuclease; a homolog thereof, a recombination of the naturally occurring molecule thereof, codon-optimized thereof, or modified versions thereof, and combinations thereof.

[000779] In another kit, Kit 11, the present disclosure provides the kit of Kits 9 or 10, comprising one or more donor template.

[000780] In another kit, Kit 12, the present disclosure provides the kit of Kit 11, wherein the donor template has homologous arms to the 17r13.1 region.

[000781] In another kit, Kit 13, the present disclosure provides the kit of Kit 11, wherein the donor template has homologous arms to a pathological variant R838H or R838C.

[000782] In another kit, Kit 14, the present disclosure provides a kit for treating a patient with autosomal dominant CORD in vivo, the kit comprising a gRNA or sgRNA for editing a R838H or R838S mutation in a GUCY2D gene, wherein the gRNA or sgRNA comprise a spacer sequence selected from the group consisting of nucleic acid sequences in SEQ ID NOs: 5434- 5443 of the Sequence Listing; one or more DNA endonucleases; and optionally, one or more donor template.

[000783] In another kit, Kit 15, the present disclosure provides the kit of Kit 14, wherein the one or more DNA endonucleases is a Casl, CaslB, Cas2, Cas3, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csnl and Csxl 2), CaslOO, Csyl, Csy2, Csy3, Cse l, Cse2, Cscl, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmrl, Cmr3, Cmr4, Cmr5, Cmr6, Csbl, Csb2, Csb3, Csxl 7, Csxl 4, CsxlO, Csxl 6, CsaX, Csx3, Csxl, Csxl 5, Csfl, Csf2, Csf3, Csf4, or Cpfl endonuclease; a homolog thereof, a recombination of the naturally occurring molecule thereof, codon-optimized thereof, or modified versions thereof, and combinations thereof.

[000784] In another kit, Kit 16, the present disclosure provides the kit of Kits 14 or 15, comprising one or more donor template.

[000785] In another kit, Kit 17, the present disclosure provides the kit of Kit 16, wherein the donor template has homologous arms to the 17r13.1 region.

[000786] In another kit, Kit 18, the present disclosure provides the kit of Kit 16, wherein the donor template has homologous arms to a pathological variant R838H or R838S. [000787] In another kit, Kit 19, the present disclosure provides a kit for treating a patient with autosomal dominant CORD in vivo, the kit comprising: any one of Self-inactivating CRISPR- Cas systems 1-35; and optionally, one or more donor template.

[000788] In another kit, Kit 20, the present disclosure provides the kit of Kit 19, comprising one or more donor template.

[000789] In another kit, Kit 21, the present disclosure provides the kit of Kit 20, wherein the donor template has homologous arms to the 17r13.1 region.

[000790] In another kit, Kit 22, the present disclosure provides the kit of Kit 20, wherein the donor template has homologous arms to a pathological variant R838H, R838C, or R838S.

[000791] In a first self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 1, the present disclosure provides a self-inactivating CRISPR-Cas system comprising: a first segment comprising a nucleotide sequence that encodes a polypeptide inducing site-directed mutagenesis; a second segment comprising a nucleotide sequence that encodes a guide RNA (gRNA) or a single-molecule guide RNA (sgRNA) wherein the gRNA or sgRNA comprise SEQ ID NO: 5285 or 5464; and one or more third segments comprising a self-inactivating (SIN) site; wherein the gRNA or sgRNA is substantially complementary to the SIN site; wherein the gRNA or sgRNA is substantially complementary to a genomic target sequence.

[000792] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 2, the present disclosure provides a self-inactivating CRISPR-Cas system comprising a first segment comprising a nucleotide sequence that encodes a a polypeptide inducing site- directed mutagenesis; a second segment comprising a nucleotide sequence that encodes a guide RNA (gRNA) or single-molecule guide RNA (sgRNA) wherein the gRNA or sgRNA comprise SEQ ID NO: 5398 or 5466; and one or more third segments comprising a self-inactivating (SIN) site; wherein the gRNA or sgRNA is substantially complementary to the SIN site; wherein the gRNA or sgRNA is substantially complementary to a genomic target sequence.

[000793] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 3, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1 or 2, wherein the polypeptide inducing site-directed mutagenesis is Streptococcus pyogenes Cas9 (SpCas9) or any variants thereof.

[000794] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 4, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-3, wherein the polypeptide inducing site-directed mutagenesis is SpCas9 or any variants thereof; and wherein the SIN site is a 5’ SIN site located 5’ of a SpCas9 open reading frame (ORF) or a 3’ SIN site located 3’ of the SpCas9 ORF.

[000795] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 5, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 4, wherein the 5’ SIN site comprises SEQ ID NO: 5327.

[000796] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 6, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 4-5, wherein the 3’ SIN site comprises SEQ ID NO: 5369.

[000797] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 7, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 4, wherein the 5’ SIN site comprises SEQ ID NO: 5326.

[000798] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 8, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 4 and 7, wherein the 3’ SIN site comprises SEQ ID NO: 5368.

[000799] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 9, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 4-5 and 7, wherein the 5’ SIN site is located upstream of the Cas9 open reading frame (ORF) and downstream of a SV40 nuclear localization signal (NLS).

[000800] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 10, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 4-5 and 7, wherein the 5’ SIN site is located upstream of the Cas9 open reading frame (ORF) and upstream of a SV40 nuclear localization signal (NLS) within a 5’ untranslated region (UTR).

[000801] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 11, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-10, where the SIN site comprises a protospacer adjacent motif (PAM).

[000802] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 12, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 11, wherein the PAM is NRG or any variants thereof.

[000803] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 13, the present disclosure provides the self-inactivating CRISPR-Cas system of Self- inactivating CRISPR-Cas systems 1-12, wherein the genomic target sequence is a R838H mutation or R838C mutation in a guanylate cyclase 2D (GUCY2D) gene.

[000804] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 14, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-13, wherein the first segment comprising a nucleotide sequence that encodes a polypeptide inducing site-directed mutagenesis, further comprises a start codon, a stop codon, and a poly(A) termination site.

[000805] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 15, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-14, wherein the first segment and the third segment are provided together in a first vector and the second segment is provided in a second vector.

[000806] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 16, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-14, wherein the first segment, second segment, and third segment are provided together in a vector.

[000807] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 17, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 15-16, wherein the third segment is present in the first or second vector at a location 5’ of the first segment.

[000808] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 18, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 15-16, wherein the third segment is present in the first or second vector at a location 3’ of the first segment.

[000809] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 19, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 15-16, wherein the one or more third segments are present in the first or second vector at the 5’ and 3’ ends of the first segment.

[000810] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 20, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 15, wherein the first vector comprises SEQ ID NO: 5508 and the second vector comprises SEQ ID NO: 5506.

[000811] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 21, the present disclosure provides the self-inactivating CRISPR-Cas system of Self- inactivating CRISPR-Cas system 15, wherein the first vector comprises SEQ ID NO: 5508 and the second vector comprises SEQ ID NO: 5507.

[000812] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 22, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 15, wherein the first vector comprises SEQ ID NO: 5509 and the second vector comprises SEQ ID NO: 5506.

[000813] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 23, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 15, wherein the first vector comprises SEQ ID NO: 5509 and the second vector comprises SEQ ID NO: 5507.

[000814] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 24, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-23, wherein the third segment is less than 100 nucleotides in length.

[000815] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 25, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 24, wherein the third segment is less than 50 nucleotides in length.

[000816] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 26, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-25, wherein the gRNA or sgRNA is fully complementary to the nucleotide sequence of the SIN site except for in at least one location.

[000817] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 27, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-26, wherein the gRNA or sgRNA is fully complementary to the nucleotide sequence of the SIN site except for in at least two locations.

[000818] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 28, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 1-27, wherein a nucleic acid sequence encoding a promoter is operably linked to the first segment.

[000819] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 29, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 28, wherein the promoter is a spatially-restricted promoter, bidirectional promoter driving gRNA or sgRNA in one direction and SpCas9 in the opposite orientation, or an inducible promoter.

[000820] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 30, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 29, wherein the spatially-restricted promoter is selected from the group consisting of: any tissue or cell type specific promoter, a hepatocyte-specific promoter, a neuron-specific promoter, an adipocyte-specific promoter, a cardiomyocyte-specific promoter, a skeletal muscle-specific promoter, lung progenitor cell specific promoter, a photoreceptor- specific promoter, and a retinal pigment epithelial (RPE) selective promoter.

[000821] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 31, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas systems 15-16, wherein the vector is one or more adeno-associated virus (AAV) vectors.

[000822] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 32, the present disclosure provides the self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 31, wherein the adeno-associated virus (AAV) vector is an AAV5 serotype capsid vector.

[000823] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 33, the present disclosure provides a self-inactivating CRISPR-Cas system comprising: a first segment comprising a nucleotide sequence that encodes a SpCas9 or any variants thereof; a second segment comprising a nucleotide sequence that encodes a guide RNA (gRNA) or a single -molecule guide RNA (sgRNA); and one or more third segments comprising a self inactivating (SIN) site; wherein the gRNA or sgRNA is substantially complementary to the SIN site; wherein the gRNA or sgRNA is substantially complementary to a genomic target sequence; wherein the SIN site comprises a sequence selected from the group consisting of SEQ ID NOs: 5478-5492.

[000824] In another self-inactivating CRISPR-Cas system, Self-inactivating CRISPR-Cas system 34, the present disclosure provides a self-inactivating CRISPR-Cas system comprising: a first segment comprising a nucleotide sequence that encodes a SpCas9 or any variants thereof; a second segment comprising a nucleotide sequence that encodes a guide RNA (gRNA) or a single -molecule guide RNA (sgRNA); and one or more third segments comprising a self inactivating (SIN) site; wherein the gRNA or sgRNA is substantially complementary to the SIN site; wherein the gRNA or sgRNA is substantially complementary to a genomic target sequence; wherein the SIN site comprises a sequence selected from the group consisting of SEQ ID NOs: 5324-5355, 5410-5421 and 5444-5453 or SEQ ID NOs: 5366-5397, 5422-5433, and 5454-5463.

[000825] In another self-inactivating CRISPR-Cas system, Self-Inactivating CRISPR-Cas system 35, the present disclosure provides a self-inactivating CRISPR-Cas system of Self inactivating CRISPR-Cas system 34, wherein the SIN site comprises a sequence 1, 2, or 3 nucleotides shorter than any one of the sequences selected from the group consisting of SEQ ID NOs: 5324-5355, 5410-5421 and 5444-5453 or SEQ ID NOs: 5366-5397, 5422-5433, and 5454- 5463.

[000826] In a first genetically modified cell, Genetically Modified Cell 1, the present disclosure provides a genetically modified cell comprising the self-inactivating CRISPR-Cas system of any of Self-inactivating CRISPR-Cas systems 1-35.

[000827] In another genetically modified cell, Geneteically Modified Cell 2, the present disclosure provides the genetically modified cell of Genetically Modified Cell 1, wherein the cell is selected from the group consisting of: an archaeal cell, a bacterial cell, a eukaryotic cell, a eukaryotic single-cell organism, a somatic cell, a germ cell, a stem cell, a plant cell, an algal cell, an animal cell, an invertebrate cell, a vertebrate cell, a fish cell, a frog cell, a bird cell, a mammalian cell, a pig cell, a cow cell, a goat cell, a sheep cell, a rodent cell, a rat cell, a mouse cell, a non-human primate cell, and a human cell.

[000828] In a first nucleic acid, Nucleic Acid 1, the present disclosure provides a nucleic acid encoding a gRNA comprising a spacer sequence selected from the group consisting of SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443.

[000829] In another nucleic acid, Nucleic Acid 2, the present disclosure provides the nucleic acid of Nucleic Acid 1, wherein the gRNA is a sgRNA.

[000830] In a first vector, Vector 1, the present disclosure provides a vector encoding a gRNA comprising a spacer sequence selected from the group consisting of SEQ ID NOs: 5282-5313, 5398-5409, and 5434-5443.

[000831] In another vector, Vector 2, the present disclosure provides the vector of Vector 1, wherein the gRNA is a sgRNA.

[000832] In another vector, Vector 3, the present disclosure provides the vector of any one of Vectors 1 or 2, wherein the vector is an AAV.

[000833] In another vector, Vector 4, the present disclosure provides the vector of any one of Vectors 1-3, wherein the vector is an AAV5 sertoype capsid vector. [000834] Definitions

[000835] In addition to the definitions previously set forth herein, the following definitions are relevant to the present disclosure:

[000836] The term“alteration” or“alteration of genetic information” refers to any change in the genome of a cell. In the context of treating genetic disorders, alterations may include, but are not limited to, insertion, deletion and correction.

[000837] The term“insertion” refers to an addition of one or more nucleotides in a DNA sequence. Insertions can range from small insertions of a few nucleotides to insertions of large segments such as a cDNA or a gene.

[000838] The term“deletion” refers to a loss or removal of one or more nucleotides in a DNA sequence or a loss or removal of the function of a gene. In some cases, a deletion can include, for example, a loss of a few nucleotides, an exon, an intron, a gene segment, or the entire sequence of a gene. In some cases, deletion of a gene refers to the elimination or reduction of the function or expression of a gene or its gene product. This can result from not only a deletion of sequences within or near the gene, but also other events (e.g., insertion, nonsense mutation) that disrupt the expression of the gene.

[000839] The term“correction” as used herein, refers to a change of one or more nucleotides of a genome in a cell, whether by insertion, deletion or substitution. Such correction may result in a more favorable genotypic or phenotypic outcome, whether in structure or function, to the genomic site which was corrected. One non-limiting example of a“correction” includes the correction of a mutant or defective sequence to a wild-type sequence which restores structure or function to a gene or its gene product(s). Depending on the nature of the mutation, correction may be achieved via various strategies disclosed herein. In one non-limiting example, a missense mutation may be corrected by replacing the region containing the mutation with its wild-type counterpart. As another example, duplication mutations (e.g., repeat expansions) in a gene may be corrected by removing the extra sequences.

[000840] The term“knock-in” refers to an addition of a DNA sequence, or fragment thereof into a genome. Such DNA sequences to be knocked-in may include an entire gene or genes, may include regulatory sequences associated with a gene or any portion or fragment of the foregoing. For example, a cDNA encoding the wild-type protein may be inserted into the genome of a cell carrying a mutant gene. Knock-in strategies need not replace the defective gene, in whole or in part. In some cases, a knock-in strategy may further involve substitution of an existing sequence with the provided sequence, e.g., substitution of a mutant allele with a wild-type copy. On the other hand, the term“knock-out” refers to the elimination of a gene or the expression of a gene. For example, a gene can be knocked out by either a deletion or an addition of a nucleotide sequence that leads to a disruption of the reading frame. As another example, a gene may be knocked out by replacing a part of the gene with an irrelevant sequence. Finally, the term “knock-down” as used herein refers to reduction in the expression of a gene or its gene product(s). As a result of a gene knock-down, the protein activity or function may be attenuated or the protein levels may be reduced or eliminated.

[000841] The term "comprising" or "comprises" is used in reference to compositions, therapeutics, kits, methods, and respective component(s) thereof, that are essential to the present disclosure, yet open to the inclusion of unspecified elements, whether essential or not.

[000842] The term "consisting essentially of refers to those elements required for a given aspect. The term permits the presence of additional elements that do not materially affect the basic and novel or functional characteristic(s) of that aspect of the present disclosure.

[000843] The term "consisting of’ refers to compositions, therapeutics, kits, methods, and respective components thereof as described herein, which are exclusive of any element not recited in that description of the aspect.

[000844] The singular forms "a," "an," and "the" include plural references, unless the context clearly dictates otherwise.

[000845] Any numerical range recited in this specification describes all sub-ranges of the same numerical precision (i.e., having the same number of specified digits) subsumed within the recited range. For example, a recited range of“1.0 to 10.0” describes all sub-ranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, such as, for example,“2.4 to 7.6,” even if the range of“2.4 to 7.6” is not expressly recited in the text of the specification. Accordingly, the Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range of the same numerical precision subsumed within the ranges expressly recited in this specification. All such ranges are inherently described in this specification such that amending to expressly recite any such sub-ranges will comply with written description, sufficiency of description, and added matter requirements, including the requirements under 35 U.S.C. § 112(a) and Article 123(2) EPC. Also, unless expressly specified or otherwise required by context, all numerical parameters described in this specification (such as those expressing values, ranges, amounts, percentages, and the like) may be read as if prefaced by the word“about,” even if the word“about” does not expressly appear before a number. Additionally, numerical parameters described in this specification should be construed in light of the number of reported significant digits, numerical precision, and by applying ordinary rounding techniques. It is also understood that numerical parameters described in this specification will necessarily possess the inherent variability characteristic of the underlying measurement techniques used to determine the numerical value of the parameter.

[000846] Any patent, publication, or other disclosure material identified herein is incorporated by reference into this specification in its entirety unless otherwise indicated, but only to the extent that the incorporated material does not conflict with existing descriptions, definitions, statements, or other disclosure material expressly set forth in this specification. As such, and to the extent necessary, the express disclosure as set forth in this specification supersedes any conflicting material incorporated by reference. Any material, or portion thereof, that is said to be incorporated by reference into this specification, but which conflicts with existing definitions, statements, or other disclosure material set forth herein, is only incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

Applicants reserve the right to amend this specification to expressly recite any subject matter, or portion thereof, incorporated by reference herein.

[000847] The details of one or more aspects of the present disclosure are set forth in the accompanying examples below. Although any materials and methods similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, specific examples of the materials and methods contemplated are now described. Other features, objects and advantages of the present disclosure will be apparent from the description. In the description examples, the singular forms also include the plural unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this present disclosure belongs. In the case of conflict, the present description will control.

Examples

[000848] The present disclosure will be more fully understood by reference to the following examples, which provide illustrative non-limiting aspects of the invention.

[000849] The examples describe the use of the CRISPR system as an illustrative genome editing technique to create defined therapeutic genomic deletions, insertions, or replacements, termed“genomic modifications” herein, within or near the R838H, R838C, or R838S mutation in the GUCY2D gene that lead to a frameshift and silencing of the expression of the mutant gene or correction of the R838H, R838C, or R838S mutation in the genomic locus, or expression at a heterologous locus, that restore RetGCl protein activity. Introduction of the defined therapeutic modifications represents a novel therapeutic strategy for the potential amelioration of autosomal dominant CORD, as described and illustrated herein.

Example 1 - Cas9 PAM sites for the R838H mutation in the

GUCY2D gene

[000850] To discover target sites for genome editing by SpCas9, the R838H mutation in the GUCY2D gene was scanned for SpCas9 protospacer adjacent motifs (PAMs). The area was scanned for PAMs having the sequence NRG. gRNA spacer sequences (17-24 bps) located immediately upstream of the NRG PAM were then identified. These sequences are candidates for use in editing the gene.

Example 2 - CRISPRAV. aureusj Sa) Cas9 PAM sites for the R838H mutation in the

GUCY2D gene

[000851] To discover target sites for genome editing by SaCas9, the R838H mutation in the GUCY2D gene was scanned for SaCas9 PAMs. The area was scanned for PAMs having the sequence NNGRRT. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNGRRT PAM were then identified. These sequences are candidates for use in editing the gene.

Example 3 - CRISPRAV. thermophilusj St) Cas9 PAM sites for the R838H mutation in the

GUCY2D gene

[000852] To discover target sites for genome editing by StCas9, the R838H mutation in the GUCY2D gene is scanned for StCas9 PAMs. The area is scanned for PAMs having the sequence NNAGAAW. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNAGAAW PAM are then identified. These sequences are candidates for use in editing the gene.

Example 4 - CRISPR/T. denticola( Td) Cas9 PAM sites for the R838H mutation in the

GUCY2D gene

To discover target sites for genome editing by TdCas9, the R838H mutation in the GUCY2D gene is scanned for TdCas9 PAMs. The area is scanned for PAMs having the sequence NAAAAC. gRNA spacer sequences (17-24 bps) located immediately upstream of the

NAAAAC PAM are then identified. These sequences are candidates for use in editing the gene.

Examnle 5 - CRISPR/ZV. meninsitidesi Nml Cas9 PAM sites for the R838H mutation in the

GUCY2D gene

[000853] To discover target sites for genome editing by NmCas9, the R838H mutation in the GUCY2D gene is scanned for NmCas9 PAMs. The area is scanned for PAMs having the sequence NNNNGHTT. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNNNGHTT PAM are then identified. These sequences are candidates for use in editing the gene.

Example 6 - CRISPR/Cpfl PAM sites for the R838H mutation in the GUCY2D gene

[000854] To discover target sites for genome editing by Cpfl, the R838H mutation in the GUCY2D gene is scanned for Cpfl PAMs. The area is scanned for PAMs having the sequence YTN. gRNA spacer sequences (17-24 bps) located immediately upstream of the YTN PAM are then identified. These sequences are candidates for use in editing the gene.

Example 7 - p) Cas9 PAM sites for the R838C mutation in the

GUCY2D gene

[000855] To discover target sites for genome editing by SpCas9, the R838C mutation in the GUCY2D gene was scanned for SpCas9 PAMs. The area was scanned for PAMs having the sequence NRG. gRNA spacer sequences (17-24 bps) located immediately upstream of the NRG PAM were then identified. These sequences are candidates for use in editing the gene.

Examnle 8 - CRISPRAV. aureusi Sal Cas9 PAM sites for the R838C mutation in the

GUCY2D gene

[000856] To discover target sites for genome editing by SaCas9, the R838C mutation in the GUCY2D gene was scanned for SaCas9 PAMs. The area was scanned for PAMs having the sequence NNGRRT. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNGRRT PAM were then identified. These sequences are candidates for use in editing the gene. Example 9 - CRISPRAV. thermophilusj St) Cas9 PAM sites for the R838C mutation in the

GUCY2D gene

[000857] To discover target sites for genome editing by StCas9, the R838C mutation in the GUCY2D gene is scanned for StCas9 PAMs. The area is scanned for PAMs having the sequence NNAGAAW. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNAGAAW PAM are then identified. These sequences are candidates for use in editing the gene.

Example 10 - CRISPR/T. denticola( Td) Cas9 PAM sites for the R838C mutation in the

GUCY2D gene

[000858] To discover target sites for genome editing by StCas9, the R838C mutation in the GUCY2D gene is scanned for TdCas9 PAMs. The area is scanned for PAMs having the sequence NAAAAC. gRNA spacer sequences (17-24 bps) located immediately upstream of the NAAAAC PAM are then identified. These sequences are candidates for use in editing the gene.

Example 11 - CRISPR/ZV. men in niticles( N m ) Cas9 PAM sites for the R838C mutation in the

GUCY2D gene

[000859] To discover target sites for genome editing by NmCas9, the R838C mutation in the GUCY2D gene is scanned for NmCas9 PAMs. The area is scanned for PAMs having the sequence NNNNGHTT. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNNNGHTT PAM are then identified. These sequences are candidates for use in editing the gene.

Example 12 - CRISPR/Cpfl PAM sites for the R838C mutation in the GUCY2D gene

To discover target sites for genome editing by Cpfl, the R838C mutation in the GUCY2D gene is scanned for Cpfl PAMs. The area is scanned for PAMs having the sequence YTN. gRNA spacer sequences (17-24 bps) located immediately upstream of the YTN PAM are then identified. These sequences are candidates for use in editing the gene.

Example 13 - Cas9 PAM sites for the R838S mutation in the

GUCY2D gene

[000860] To discover target sites for genome editing by SpCas9, the R838S mutation in the GUCY2D gene was scanned for SpCas9 PAMs. The area was scanned for PAMs having the sequence NRG. gRNA spacer sequences (17-24 bps) located immediately upstream of the NRG PAM were then identified. These sequences are candidates for use in editing the gene.

Example 14 - CRISPRAV. aureus(Sa) Cas9 PAM sites for the R838S mutation in the

GUCY2D gene

[000861] To discover target sites for genome editing by SaCas9, the R838S mutation in the GUCY2D gene was scanned for SaCas9 PAMs. The area was scanned for PAMs having the sequence NNGRRT. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNGRRT PAM were then identified. These sequences are candidates for use in editing the gene.

Example 15 - CRISPRAV. thermophilusj St) Cas9 PAM sites for the R838S mutation in the

GUCY2D gene

[000862] To discover target sites for genome editing by StCas9, the R838S mutation in the GUCY2D gene is scanned for StCas9 PAMs. The area is scanned for PAMs having the sequence NNAGAAW. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNAGAAW PAM are then identified. These sequences are candidates for use in editing the gene.

Example 16 - CRISPR/T. denticola( Td) Cas9 PAM sites for the R838S mutation in the

GUCY2D gene

[000863] To discover target sites for genome editing by TdCas9, the R838S mutation in the GUCY2D gene is scanned for TdCas9 PAMs. The area is scanned for PAMs having the sequence NAAAAC. gRNA spacer sequences (17-24 bps) located immediately upstream of the NAAAAC PAM are then identified. These sequences are candidates for use in editing the gene.

Example 17 - CRISPR/ZV. meninsitides^m) Cas9 PAM sites for the R838S mutation in the

GUCY2D gene

[000864] To discover target sites for genome editing by NmCas9, the R838S mutation in the GUCY2D gene is scanned for NmCas9 PAMs. The area is scanned for PAMs having the sequence NNNNGHTT. gRNA spacer sequences (17-24 bps) located immediately upstream of the NNNNGHTT PAM are then identified. These sequences are candidates for use in editing the gene. Example 18 - CRISPR/Cpfl PAM sites for the R838S mutation in the GUCY2D gene

[000865] To discover target sites for genome editing by Cpfl, the R838S mutation in the GUCY2D gene is scanned for Cpfl PAMs. The area is scanned for PAMs having the sequence YTN. gRNA spacer sequences (17-24 bps) located immediately upstream of the YTN PAM are then identified. These sequences are candidates for use in editing the gene.

Example 19 - Design of R838CH double mutation sgRNAs

[000866] One problem that can arise with gene editing is specificity. A particular challenge addressed by some examples provided herein is to induce effective levels of editing in a targeted mutant allele while maintaining the integrity of wild type alleles. Furthermore, applicants were able to design gRNAs that can be used to target multiple specific mutations.

[000867] To assess alternative gRNAs and decrease targeting of the wild-type GUCY2D allele by gRNAs of the present disclosure, gRNAs that can direct editing of either the R838C allele or the R838H allele were designed. As described in previous examples, PAMs and corresponding sgRNA spacer sequences were identified for the R838C and R838H GUCY2D mutations. These two mutations occur in sequential base pairs in the GUCY2D gene, but typically do not both occur in a single patient. Applicants designed gRNAs or sgRNAs that can hybridize to (e.g., bind to) and target either mutation with a single mismatch. For example, these“R838CH double mutation” sgRNAs can hybridize with an R838C GUCY2D allele in a cell of a first patient, or, separately, with an R838H GUCY2D allele in a cell of a second patient. In each case, there is a single mismatch between the sgRNA and the mutant allele, but editing at the target locus still occurs.

[000868] An additional advantageous feature of such double mutation gRNAs or sgRNAs is that when hybridizing with a wild-type GUCY2D sequence, the double mutation gRNA or sgRNA, for example, an R838CH double mutation sgRNA, has two consecutive mismatches.

The presence of two consecutive mismatches causes reduced off-target editing at the wild-type locus, compared to wild-type off-target editing caused by a single mutation sequence such as either R838C or R838H sgRNAs that bind to a wild-type GUCY2D allele with only one mismatch.

[000869] Table 7 below shows various groupings of sgRNA spacer sequences that are 19 or 20 nucleotides in length and that result in zero, one, or two mismatches when binding to the wild- type GUCY2D gene and zero or one mismatches when binding to a mutant GUCY2D allele. Bolded bases within the sgRNA sequence show the potential mismatch locations (which are also the individual bases altered by the various R838 mutations). The sgRNA spacer sequences in Table 7 are named for the allele to which they bind with zero mismatches, except for the R838CH double mutation sgRNA spacer sequences, which are named to show that they can bind either the R838C or the R838H mutant allele with one mismatch.

Table 7

[000870] These R838CH double mutation sgRNAs were designed starting from spacer sequences designed to target the R838H mutation (see Examples 1-2) and separate spacer sequences designed to target the R838C mutation (see Examples 7-8). For example, in the first grouping of Table 7, SEQ ID NOs: 5284 and 5296 are shown. SEQ ID NO: 5284 targets the R838H mutation and SEQ ID NO: 5296 targets the R838C mutation. A R838CH double mutation spacer sequence, such as SEQ ID NO: 5398, can be designed by manipulating the bases shown in bold typeface in SEQ ID NOs: 5284 and 5296. For example, SEQ ID NO: 5398 was designed by replacing the bolded C residue in SEQ ID NO: 5284 with the bolded U residue in SEQ ID NO: 5296 to yield the bolded UA sequence in SEQ ID NO: 5398. SEQ ID NO: 5398 could also be designed by starting with SEQ ID NO: 5296 and replacing the bolded G residue with an A residue of SEQ ID NO: 5284 to yield the bolded UA sequence in SEQ ID NO: 5398. SEQ ID NOs: 5284, 5296, and 5398 are all 20mer spacer sequences.

[000871] A similar process was used to generate the l9mer R838CH double mutation spacer sequence identified as SEQ ID NO: 5403, starting from SEQ ID NOs: 5289 and 5301.

[000872] A similar process was used to generate the sgRNAs in the remaining groupings in Table 7.

[000873] SEQ ID NOs: 5274 and 5278 (which bind to the wild-type GUCY2D allele with zero mismatches) are also shown in the first grouping of Table 7 as a reference to the wild-type GUCY2D sequence.

[000874] SEQ ID NOs: 5398-5407 refer to sgRNA spacer sequences of R838CH double mutation sgRNAs that associate with SpCas9. SEQ ID NOs: 5408-5409 refer to sgRNA spacer sequences of R838CH double mutation sgRNAs that associate with SaCas9.

[000875] The R838CH double mutation gRNAs of the present disclosure can allow for more specific editing of the R838C and/or R838H mutant alleles while reducing off-target editing of a wild type allele.

Example 20 - Design of R838SH double mutation sgRNAs

[000876] To assess gRNAs and decrease targeting of the wild-type GUCY2D allele by gRNAs of the present disclosure, gRNAs that can direct editing of either the R838S allele or the R838H allele were designed. As described in previous examples, PAMs and corresponding sgRNA spacer sequences were identified for the R838S and R838H GUCY2D mutations. These two mutations occur in sequential base pairs in the GUCY2D gene, but typically do not both occur in a single patient. Applicants designed gRNAs or sgRNAs that can hybridize to (e.g., bind to) and target either mutation with a single mismatch. For example, these“R838SH” double mutation sgRNAs can hybridize with an R838S GUCY2D allele in a cell of a first patient, or, separately, with an R838H GUCY2D allele in a cell of a second patient. In each case, there is a single mismatch between the sgRNA and the mutant allele, but editing at the target locus still occurs.

[000877] An additional advantageous feature of such double mutation gRNAs or sgRNAs is that when hybridizing with a wild-type GUCY2D sequence, the double mutation gRNA or sgRNA, for example, a R838SH double mutation sgRNA, has two consecutive mismatches. The presence of two consecutive mismatches causes reduced off-target editing at the wild-type locus, compared to wild-type off-target editing caused by a single mutation sequence such as either R838S or R838H sgRNAs that bind to a wild-type GUCY2D allele with only one mismatch.

[000878] Table 8 below shows various groupings of sgRNA spacer sequences that are 19 or 20 nucleotides in length and that result in zero, one, or two mismatches when binding to the wild- type GUCY2D gene and zero or one mismatches when binding to a mutant GUCY2D allele. Bolded bases within the sgRNA sequence show the potential mismatch locations (which are also the individual bases altered by the various R838 mutations). The sgRNA spacer sequences in Table 8 are named for the allele to which they bind with zero mismatches, except for the R838SH double mutation sgRNA spacer sequences, which are named to show that they can bind either the R838S or the R838H mutant allele with one mismatch.

Table 8

[000879] These R838SH double mutation sgRNAs were designed starting from spacer sequences designed to target the R838H mutation (see Examples 1-2) and separate spacer sequences designed to target the R838S mutation (see Examples 13-14). For example, in the first grouping of Table 8, SEQ ID NOs: 5284 and 5304 are shown. SEQ ID NO: 5284 targets the R838H mutation and SEQ ID NO: 5304 targets the R838S mutation. An R838SH double mutation spacer sequence can be designed by manipulating the bases shown in bold typeface.

For example, a R838SH double mutation sgRNA, such as SEQ ID NO: 5437, was designed by replacing the bolded C residue in SEQ ID NO: 5284 with the bolded A residue in SEQ ID NO: 5304 to yield the bolded AA sequence. This same R838SH double mutation sgRNA could also be designed by starting with SEQ ID NO: 5304 and replacing the bolded G residue with an A residue of SEQ ID NO: 5284 to yield the bolded AA sequence. SEQ ID NOs: 5284, 5304, and 5437 are all 20mer spacer sequences.

[000880] A similar process was used to generate the l9mer R838SH double mutation spacer sequence identified as SEQ ID NO: 5440, starting from SEQ ID NOs: 5289 and 5309.

[000881] A similar process was used to generate the sgRNAs in the remaining groupings in Table 8.

[000882] SEQ ID NOs: 5274 and 5278 (which bind to the wild-type GUCY2D allele with zero mismatches) are also shown in the first grouping of Table 8 as a reference to the wild-type GUCY2D sequence. [000883] SEQ ID NOs: 5436-5443 refer to sgRNA spacer sequences of R838SH double mutation sgRNAs that associate with SpCas9. SEQ ID NOs: 5434-5435 refer to sgRNA spacer sequences of R838SH double mutation sgRNAs that associate with SaCas9.

[000884] The R838SH double mutation gRNAs of the present disclosure can allow for more specific editing of the R838S and/or R838H mutant alleles, while reducing off-target editing of a wild-type allele.

Example 21 - Bioinformatics analysis of the guide RNAs

[000885] A gRNA or sgRNA can direct an RNP complex to an on-target site such as a genomic sequence for which editing is desired but may also have the potential to interact with an off- target site for which editing is not desired. To identify candidate gRNAs or sgRNAs that were likely to have on-target and/or off- target activity, candidate gRNAs were screened and selected in a single process or multi-step process that used both in silico analysis of binding and experimentally assessed activity at both on-target and off-target sites.

[000886] By way of illustration, candidate gRNAs having sequences that match a particular on- target site, such as a site within or near the R838H, R838C, or R838S mutation in the GUCY2D gene, with an adjacent PAM were assessed for their potential to cleave at off-target sites having similar sequences, using one or more of a variety of bioinformatics tools. Such tools for assessing off-target binding are known in the art, examples of which are described and illustrated in more detail below.

[000887] Candidates predicted to have relatively lower potential for off-target activity were then assessed in in vitro experiments to measure their on-target activity and off-target activities at various sites. Guide RNAs having sufficiently high on-target activity to achieve desired levels of gene editing at the selected locus, and relatively lower off-target activity to reduce the likelihood of alterations at other chromosomal loci are useful for modifying mutant GUCY2D. The ratio of on-target to off-target activity is often referred to as the "specificity" of a guide.

[000888] For initial screening of predicted off-target activities, bioinformatics tools known and publicly available were used to predict the most likely off-target sites. Because binding to target sites in the CRISPR/Cas9/Cpfl nuclease system is driven by Watson-Crick base pairing between complementary sequences, the degree of dissimilarity (and therefore reduced potential for off- target binding) was related to primary sequence differences: mismatches and bulges, i.e. bases that were changed to a non-complementary base, and insertions or deletions of bases in the potential off-target site relative to the target site. An exemplary bioinformatics tool called COSMID (CRISPR Off-target Sites with Mismatches, Insertions and Deletions) (available at crispr.bme.gatech.edu) compiles such similarities. Other bioinformatics tools include, but are not limited to autoCOSMID and CCTop.

[000889] Bioinformatics tools were used to minimize off-target cleavage in order to reduce the detrimental effects of mutations and chromosomal rearrangements. Studies on CRISPR /Cas9 systems suggested the possibility of off-target activity due to non-specific hybridization of the guide strand to DNA sequences with base pair mismatches and/or bulges, particularly at positions distal from the PAM region. Therefore, it was important to have a bioinformatics tool that identified potential off-target sites that have insertions and/or deletions between the RNA guide strand and genomic sequences, in addition to base-pair mismatches. Bioinformatics tools based upon the off-target prediction algorithm CCTop were used to search genomes for potential CRISPR off-target sites (CCTop is available on the web at crispr.cos.uni-heidelberg.de/). The output ranked lists of the potential off-target sites based on the number and location of mismatches, allowing more informed choice of target sites, and avoiding the use of sites with more likely off-target cleavage.

[000890] Additional bioinformatics pipelines were employed that weigh the estimated on- and/or off-target activity of gRNA targeting sites in a region. Other features that were used to predict activity include information about the cell type in question, DNA accessibility, chromatin state, transcription factor binding sites, transcription factor binding data, and other CHIP-seq data. Additional factors were weighed that predict editing efficiency, such as relative positions and directions of pairs of gRNAs, local sequence features and micro-homologies.

[000891] These processes allow for selection of high specificity gRNAs or sgRNAs for further development.

Example 22 - Testing of guide RNAs in cells for off-target activity

To further evaluate the specificity of gRNAs provided herein, selected gRNAs predicted to have the lowest off-target activity were tested for off-target editing efficiency.

[000892] HEK 293FT cells with SpCas9 open reading frame (ORF) regulated by a constitutive promoter integrated into the AAVS1 locus were cultured in 10 % heat inactivated (HI)

FBS/DMEM supplemented with 1 pg/ml puromycin, and passaged every 3-4 days.

[000893] The HEK 293FT cell line expressing SpCas9 was seeded in 100 pl of 10 % HI- FBS/DMEM at 50,000 cells per well in a 96-well plate, and transfected with 1 pg of sgRNA using Lipofectamine® MessengerMax™ (available from Thermo Fisher Scientific, Massachusets, US). sgRNAs used for this assay were synthesized by in vitro transcription (IVT). The DNA fragments containing bacteriophage T7 promoter, protospacer and sgRNA tracer sequences were generated by assembling oligonucleotides through PCR. IVT was performed using the TranscriptAid T7 High Yield Transcription Kit (available from Thermo Fisher Scientific), and the synthesized RNA strands were purified using either ZR-96 RNA Clean & Concentrator™ (available from Zymo Research, California, US) or RNAClean XP beads (available from Beckman Coulter, California, US).

[000894] At 48 hours post-transfection, medium was removed and total DNA was extracted using prepGem® Tissue Kit (available from VWR, Pennsylvania, US). The sequence surrounding the Cas9 target sites on the genome was PCR-amplified. The Cas9 target sites on the genome were the wild-type GUCY2D locus, the R838H mutation, the R838C mutation, or the R838S mutation. The resulting products were cleaned up using AMPure XP beads (available from Beckman Coulter), and sequenced to assess Cas9-mediated genetic modifications. The frequencies of small insertions and deletions (indels) were estimated using TIDE.

[000895] On-target editing efficiency was determined at the wild-type GUCY2D locus via TIDE analysis for sgRNAs that target the wild-type GUCY2D gene (Figures 4A-D; sgRNAs comprising SEQ ID NOs: 5274, 5278, 5275, 5279, 5276, 5280, 5277, or 5281). These sgRNAs that target the wild-type GUCY2D locus were used as positive controls to measure on-target editing at the wild-type GUCY2D locus.

[000896] Off-target editing efficiency was determined at the wild-type GUCY2D locus via TIDE analysis for sgRNAs that target the R838H mutation (Figures 4A-E; sgRNAs comprising SEQ ID NOs: 5284, 5289, 5285, 5290, 5286, 5291, 5287, 5292, 5288, or 5293).

[000897] Off-target editing efficiency was also determined at the wild-type GUCY2D locus via TIDE analysis for sgRNAs that target the R838C mutation (Figures 4A-D; sgRNAs comprising SEQ ID NOs: 5296, 5300, 5297, 5301, 5298, 5302, 5299, or 5303).

[000898] Off-target editing efficiency was also determined at the wild-type GUCY2D locus via TIDE analysis for sgRNAs that target the R838S mutation (Figures 4A-D; sgRNAs comprising SEQ ID NOs: 5304, 5308, 5305, 5309, 5306, 5310, 5307, or 5311).

[000899] Off-target editing efficiency was also determined at the wild-type GUCY2D locus via TIDE analysis for sgRNAs that are able to target both the R838H mutation and R838C mutation (Figures 4A-E; sgRNAs comprising SEQ ID NOs: 5398, 5403, 5399, 5404, 5400, 5405, 5402, 5407, 5401, or 5406). [000900] These data provide evidence that the selected gRNAs can minimize off-target activity (Figures 4A-E).

Example 23 - Testing of guide RNAs in cells for on-target activity

[000901] To further evaluate the specificity of gRNAs provided herein, selected gRNAs predicted to have the lowest off-target activity were also tested for on-target editing efficiency.

[000902] HEK 293FT cells expressing SpCas9 were collected and resuspended in SF solution at 10,000,000 cells per ml. 20 pl of the cell suspension was transfected with 2pg of sgRNA and 200, 400 or 800 ng of either a plasmid encoding the wild-type GUCY2D gene or a plasmid encoding the R838H mutation. The transfection of the HEK 293 FT cells was performed by nucleofection under the program CM-130 using Lonza 4D nucleofector system.

[000903] sgRNAs used for this assay were synthesized by IVT. The DNA fragments containing bacteriophage T7 promoter, protospacer and sgRNA tracer sequences were generated by assembling oligonucleotides through PCR. IVT was performed using TranscriptAid T7 High Yield Transcription Kit, and the synthesized RNA strands were purified using either ZR-96 RNA Clean & Concentrator™ or RNA clean XP beads (Beckman Coulter).

[000904] A plasmid encoding the wild-type GUCY2D gene or a plasmid encoding GUCY2D comprising the R838H mutation was built by two rounds of molecular cloning. First, pSpCas9 (purchased from Genscript, New Jersey, US) was digested with KpnI-HF and EcoRI-HF, and a PCR fragment containing human rhodopsin kinase promoter (GRK1) and the sequence encoding the amino-acid residue 962 through the C-terminus of human GUCY2D was inserted between the two digestion sites.

[000905] The resulting plasmid and ORF cDNA clones encoding the wild type GUCY2D (purchased from Genecopoeia) were digested with BstBI and Ndel, and the linearized fragments were ligated with T4 DNA ligase to insert the full-length wild-type GUCY2D gene downstream of the GRK1 promoter.

[000906] In addition, the resulting plasmid and ORF cDNA clones encoding the R838H mutation (purchased from Genecopoeia) were digested with BstBI and Ndel, and the linearized fragments were ligated with T4 DNA ligase to insert the full-length R838H containing GUCY2D gene downstream of the GRK1 promoter.

[000907] Each 25 mΐ of the nucleofection samples was transferred into l-well containing 175 mΐ of 10% HI-FBS/DMEM in 96-well plates. At 48-hours post-transfection, each well was washed with PBS twice, and total DNA was extracted using prepGem® Tissue Kit. The sequence surrounding Cas9 target sites on the plasmid DNA was PCR-amplified. The resulting products were cleaned up using AMPure XP beads, and sequenced to assess Cas9-mediated genetic modifications. The frequencies of small insertions and deletions (indels) were estimated using TIDE.

[000908] On-target editing efficiency was determined at the wild-type GUCY2D locus via TIDE analysis for sgRNAs that target the wild-type GUCY2D gene (Figure 5; sgRNAs comprising SEQ ID NO: 5274).

[000909] On-target editing efficiency was also determined at the R838H mutation of the GUCY2D gene via TIDE analysis for sgRNAs that target the R838H mutation (Figure 5;

sgRNAs comprising SEQ ID NO: 5284, 5285, 5286, 5287, or 5288).

[000910] On-target editing efficiency was also determined at the R838H mutation of the GUCY2D gene via TIDE analysis for sgRNAs that are able to target both the R838H mutation and R838C mutation (Figure 5; sgRNAs comprising SEQ ID NO: 5398, 5399, 5400, 5401, or 5402).

[000911] These data provide evidence that selected gRNAs designed by Applicants can effectively edit a GUCY2D gene harboring a R838H mutation (Figure 5).

Example 24 - Testing of guide RNAs in cells for on-target and off-target activity

[000912] To further evaluate the specificity of gRNAs provided herein, selected gRNAs were further tested for on-target and off-target activity.

[000913] A sequence containing human U6 promoter, seamless protospacer cloning site, sgRNA tracer, CMV promoter, chimeric intron, EGFP ORF, WPRE and SV40 polyadenylation signal was synthesized using GeneArt service (ThermoFisher Scientific). This sequence was separated from the vector backbone by digestion with MluI-HF and RsrII, and cloned between the same sites on the AAV vector. The resulting plasmid (pSIA003) was digested with Sapl, and synthesized oligonucleotides were annealed to generate protospacers with 3-nt overhangs compatible with those of the linearized pSIA003. The double-stranded protospacers were inserted into pSIA003 by DNA ligation.

[000914] HEK 293FT SpCas9-expressing cells were transfected with 200, 400 or 800 ng of pSIA003, which contains a U6-driven sgRNA. HEK 293FT SpCas9 expressing cell samples were referenced in Figures 6A-B as 2, 4, and 8 in their sample names depending on the concentration of pSIA003 that was used (200, 400, or 800 ng). At the same time that HEK 293FT SpCas9-expressing cells were transfected with pSIA003, they were also transfected with 200 ng of a plasmid encoding the wild-type GUCY2D gene, a plasmid encoding GUCY2D comprising the R838H mutation, or a plasmid encoding GUCY2D comprising the R838C mutation. The transfection of the HEK 293FT cells was performed by nucleofection under the program CM- 130 using a Lonza 4D-Nucleofector™ system (available from Lonza, Switerlzand).

[000915] Each 25 pl of the nucleofection samples was transferred into l-well containing 175 mΐ of 10 % HI-FBS/DMEM in 96-well plates. At 48 and 72 hours post-transfection, each well was washed with PBS twice, then total DNA was extracted using prepGem Tissue Kit. The sequence surrounding Cas9 target sites on the plasmid DNA was PCR-amplified. The resulting products were cleaned up using AMPure XP beads, and sequenced to assess Cas9-mediated genetic modifications. The frequencies of small insertions and deletions (indels) were estimated using TIDE.

[000916] On-target editing efficiency was determined at the wild-type GUCY2D locus via TIDE analysis for a sgRNA that targets the wild-type GUCY2D gene (sgRNA comprising SEQ ID NO: 5274) at 48 hours (Figure 6A) and 72 hours (Figure 6B) post-transfection.

[000917] On-target and off-target editing efficiency was also determined at the wild-type GUCY2D locus, the R838H mutation of the GUCY2D gene, and the R838C mutation of the GUCY2D gene via TIDE analysis for sgRNAs that target the R838H mutation (sgRNAs comprising SEQ ID NOs: 5285 or 5286) at 48 hours (Figure 6A) and 72 hours (Figure 6B) post transfection.

[000918] On-target and off-target editing efficiency was also determined at the wild-type GUCY2D locus, the R838H mutation of the GUCY2D gene, and the R838C mutation of the GUCY2D gene via TIDE analysis for sgRNAs that are able to target both the R838H mutation and R838C mutation (sgRNAs comprising SEQ ID NOs: 5398, 5399, or 5402) at 48 hours (Figures 6A) and 72 hours (Figure 6B) post-transfection.

[000919] These data provide evidence that the selected gRNAs can effectively edit the

GUCY2D mutations R838C and R838H while minimizing off-target activity (Figures 6A-B).

Example 25 - Testing of guide RNAs in cells for on-target and off-target activity

[000920] To further evaluate the specificity of gRNAs provided herein, selected gRNAs were further tested for on-target and off-target activity when targeting a genomic GUCY2D allele for editing.

[000921] Three reporter cell lines were generated that contain a Cas9 target site fused to a blue fluorescent protein at the beta-tubulin gene locus. The first reporter cell line has a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus. The second reporter cell line has a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus. The third reporter cell line has a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus.

[000922] These three reporter cell lines were generated using pDLl24 and a donor plasmid. pDLl24 contains a SpCas9 ORF under CMV promoter and a U6 promoter-driven sgRNA and was built by Gibson assembly. The U6 promoter-driven sgRNA can cut the codon

corresponding to the third residue from the C-terminus of beta-tubulin. A donor plasmid (Figure 7A) comprises a Cas9 target site (either a wild-type GUCY2D gene, a GUCY2D gene comprising a R838H mutation, or a GUCY2D gene comprising a R838C mutation). Each of these 3 donor plasmids was synthesized using GeneArt service (ThermoFisher Scientific).

[000923] HEK 293FT cells (200,000 cells) were transfected with 0.5 pg of pDLl24 and 0.5 pg of donor plasmid by nucleofection under the program DN-100. pDLl24 was used to generate a double-strand break at the beta-tubulin gene locus of the HEK 293FT cells in order to integrate the Cas9 target site (i.e. the wild-type GUCY2D gene, the GUCY2D gene comprising the R838H mutation, or the GUCY2D gene comprising the R838C mutation) from the donor plasmid and into the beta-tubulin gene locus of the HEK 293FT cells between the two homologous arms (tubb exon 4). Homologous recombination leads to expression of beta-tubulin fused to T2A peptide. The Cas9 target site includes no stop codon, and blue fluorescent protein (mTagBFP2) and blasticidin selection marker (bsd) are encoded in the same reading frame as for beta-tubulin. Cells with a Cas9 target site integrated correctly were enriched in 10 % FBS/DMEM

supplemented with 2-5 pg/ml blasticidin, and isolated by cell sorting. Each of the reporter cell lines was seeded in 2.5 ml of 10 % FBS/DMEM at 500,000 cells per well in 6-well plates 24 hours before transfection.

[000924] The reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg pSIA043 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 7B). pSIA043 encodes Cas9. A nucleotide sequence containing GRKl-driven SpCas9 and SV40 polyadenylation signal was synthesized using GeneArt service (ThermoFisher Scientific), and transferred onto the AAV vector by conventional DNA cloning techniques. The human elongation factor 1 alpha promoter was PCR-amplified, and substituted for GRK1 promoter. The resulting plasmid was designated as pSIA043. pSIA0l2 is pAAV-5285, which comprises an AAV sequence that encodes for R838H_Sp_T2 sgRNA (a sgRNA comprising SEQ ID NO: 5285) and EGFP (SEQ ID NO:

5469).

[000925] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg pSIA043 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 7E).

[000926] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg pSIA043 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 7H).

[000927] The reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg pSIA043 and

1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 7C). pSIA0l5 is pAAV-5398, a pAAV comprising a sequence that encodes for R838CH_Sp_Tl sgRNA (a sgRNA comprising SEQ ID NO: 5398) and EGFP (SEQ ID NO: 5471).

[000928] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg pSIA043 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 7F).

[000929] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg pSIA043 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 71).

[000930] The reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with only transfection reagent (no DNA) using Lipofectamine® 3000 (Figure 7D).

[000931] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with only transfection reagent (no DNA) using Lipofectamine® 3000 (Figure 7G).

[000932] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with only transfection reagent (no DNA) using Lipofectamine® 3000 (Figure 7J).

[000933] At 72 hours post-transfection, reporter cells were dissociated from the plates by incubation with trypsin-EDTA, and analyzed for blue fluorescence (BFP) and green fluorescence (GFP) by flow cytometry. A frame-shift induced by genome editing at a Cas9 target site (whether the Cas9 target site is the wild-type GUCY2D gene, the GUCY2D gene comprising the R838H mutation, or the GUCY2D gene comprising the R838C mutation) of the HEK 293FT cell results in loss of BFP. EGFP and sgRNA are encoded on the same vector and the EGFP serves as a transfection marker. Therefore, HEK 293FT cells transfected with pSIA0l2 (which comprises a sequence that encodes R838H_Sp_T2 sgRNA - a sgRNA comprising SEQ ID NO: 5285) or pSIA0l5 (which comprises a sequence that encodes R838CH_Sp_Tl sgRNA - a sgRNA comprising SEQ ID NO: 5398) are GFP positive.

[000934] Gene editing in the transfected cells was estimated in the cell populations plotted within gate“B” (Figures 7B-7J). The bolded percentages in Figures 7B-7J indicate BFP negative and GFP positive cells within gate“B”. BFP negative means that gene editing occurred at the Cas9 target site of these transfected HEK 293FT cells. GFP positive means that these transfected HEK 293FT cells contain a plasmid that encodes EGFP and sgRNA.

[000935] Figure 7B shows that of the transfected HEK 293FT reporter cells that have the wild- type GUCY2D gene as the Cas9 target site, 16.67% of these cells had the wild-type GUCY2D gene edited when R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) was used as the sgRNA.

[000936] Figure 7C shows that of the transfected HEK 293FT reporter cells that have the wild- type GUCY2D gene as the Cas9 target site, 3.38% of these cells had the wild-type GUCY2D gene edited when R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) was used as the sgRNA.

[000937] Figure 7D shows that of the transfected HEK 293FT reporter cells that have the wild- type GUCY2D gene as the Cas9 target site, 0% of these cells had the wild-type GUCY2D gene edited when no sgRNA was used.

[000938] Figure 7E shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site, 52.37% of these cells had the R838H mutation edited when R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) was used as the sgRNA.

[000939] Figure 7F shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site, 16.14% of these cells had the R838H mutation edited when R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) was used as the sgRNA.

[000940] Figure 7G shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site, 0% of these cells had the R838H mutation edited when no sgRNA was used.

[000941] Figure 7H shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site, 1.89% of these cells had the R838C mutation edited when R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) was used as the sgRNA. [000942] Figure 71 shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site, 24.47% of these cells had the R838C mutation edited when R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) was used as the sgRNA.

[000943] Figure 7J shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site, 0% of these cells had the R838C mutation edited when no sgRNA was used.

[000944] Because no genome editing was induced in mock transfected cells, the vast majority of mock transfected cells are BFP positive (Figures 7D, 7G, and 7J).

[000945] Genomic DNA was also extracted from reporter cells 72-hours post-transfection using Zymo Research Quick-DNA plus kit. The sequence spanning Cas9 target sites upstream of the fluorescent protein gene was PCR-amplified, and indels were analyzed by TIDE (data not shown). The results of those data not shown were in agreement with the results observed by flow cytometry analysis.

[000946] These data provide evidence that the tested gRNAs can effectively edit the mutant R838H GUCY2D gene and R838C GUCY2D gene while minimizing off-target activity (Figures 7B-J).

Example 26 - cGMP functional assay

[000947] The GUCY2D protein is a guanylate cyclase, which synthesizes cGMP in mammalian photoreceptor cells. A cGMP functional assay was established as an on-target screening approach for R838H sgRNA screening. In the assay, in vitro-transcribed (IVT) sgRNAs and a vector containing R838H cDNA were co-transfected into HEK293T-SpCas9 cells. Editing of the R838H cDNA can result in reduction of GUCY2D protein production, and consequently decreased cGMP signal. Assays were also conducted using AAV-encoded sgRNAs. The editing efficiency of gRNAs was directly proportional to the percent reduction of cGMP in cells transfected with sgRNAs.

[000948] A total of 10 sgRNAs targeting the R838H mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NOs: 5284, 5285, 5286, 5287, 5288, 5289, 5290, 5291, 5292, or 5293) were screened for on-target editing using the cGMP functional assay. To calculate percent reduction of cGMP (Figure 8A), HEK293T-SpCas9 cells co-transfected with (1) a R838H IVT sgRNA and (2) a vector containing R838H cDNA were compared to HEK293T-SpCas9 cells that were not transfected with any sgRNA but did receive the cDNA vector. For example, HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5284 had a 69.1% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5284 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5285 had a 72.5% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5285 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5286 had a 51.9% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5286 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5287 had a 25.9% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5287 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5288 had a 28.1% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5288 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5289 had a 73.1% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5289 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5290 had a 70.3% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5290 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5291 had a 60.1% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5291 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5292 had a 47.8% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5292 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5293 had a 20.9% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5293 was able to edit the R838H mutation within the GUCY2D gene. Absolute cGMP was also determined for these same samples (Figure 8B).

[000949] A sgRNA comprising SEQ ID NO: 5277 that targets the wild-type GUCY2D gene and a vector containing wild-type GUCY2D cDNA were co-transfected into HEK293T-SpCas9 cells and used as a control. Editing of wild-type GUCY2D cDNA using the sgRNA that targets the wild-type GUCY2D gene resulted in an 80% reduction of cGMP (data not shown), which demonstrates that the sgRNA comprising SEQ ID NO: 5277 was able to edit the wild-type GUCY2D. Percent reduction of cGMP was calculated by comparing the cGMP levels of cells transfected with the sgRNA comprising SEQ ID NO: 5277 that targets the wild-type GUCY2D gene compared to cells that were not transfected with any sgRNAs (data not shown). Editing of wild-type GUCY2D cDNA using the sgRNA that targets the wild-type GUCY2D gene resulted in -225 nM cGMP (data not shown).

[000950] In a second cGMP functional assay, an IVT sgRNA and a vector containing R838H cDNA were co-transfected into HEK293T-SpCas9 cells. Three sgRNAs that target the R838H mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NOs: 5285, 5286 or 5291) were screened for on-target editing using the cGMP functional assay. To calculate percent reduction of cGMP (Figure 9A), HEK293T-SpCas9 cells co-transfected with (1) a R838H IVT sgRNA and (2) a vector containing R838H cDNA were compared to HEK293T-SpCas9 cells that were not transfected with any sgRNA but did receive the cDNA vector. For example, HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5285 had an 82.7% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5285 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5286 had a 60.5% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5286 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and sgRNA comprising SEQ ID NO: 5291 had a 69.1% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5291 was able to edit the R838H mutation within the GUCY2D gene. Absolute cGMP was also determined for these same samples (Figure 9B)

[000951] In a third cGMP functional assay, an AAV vector encoding a sgRNA driven by a U6 promoter (pAAV-U6-sgRNA) and a vector containing R838H cDNA were co-transfected into HEK293T-SpCas9 cells. sgRNAs that target the R838H mutation within the GUCY2D gene (sgRNAs comprising SEQ ID NOs: 5285 or 5286) were screened for on-target editing using the cGMP functional assay. Percent reduction of cGMP (Figure 10A) was calculated by comparing the cGMP level of HEK293T-SpCas9 cells co-transfected with a pAAV-U6-R838H sgRNA and a vector containing R838H cDNA with HEK293T-SpCas9 cells that were not transfected with any pAAV-U6- R838H sgRNA. For example, HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and pSIA0l2 (also called pAAV-5285), a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5285) had a 41.3% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5285 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and pAAV-U6-R838H sgRNA (also called pAAV-5286, a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5286) had a 16.5% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5286 was able to edit the R838H mutation within the GUCY2D gene. HEK293T-SpCas9 cells co-transfected with a vector containing R838H cDNA and pAAV-U6-WT sgRNA (a pAAV-5274, a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5274) had a 0% reduction of cGMP, which demonstrates that the sgRNA comprising SEQ ID NO: 5274 was not able to edit the R838H mutation within the GUCY2D gene. Absolute cGMP was also determined for these same samples (Figure 10B)

[000952] An AAV vector encoding a sgRNA driven by a U6 promoter that targets the wild- type GUCY2D gene (pAAV-5274, a plasmid comprising an AAV sequence that encodes for a sgRNA comprising SEQ ID NO: 5274) and a vector containing wild-type GUCY2D cDNA were co-transfected into HEK293T-SpCas9 cells and used as a control. Editing of wild-type

GUCY2D cDNA using the sgRNA comprising SEQ ID NO: 5274 that targets the wild-type GUCY2D gene resulted in a 42.2% reduction of cGMP (data not shown), which demonstrates that the sgRNA comprising SEQ ID NO: 5274 was able to edit the wild-type GUCY2D. Percent reduction of cGMP was calculated by comparing the cGMP level of HEK293T-SpCas9 cells co transfected with a sgRNA comprising SEQ ID NO: 5274 that targets the wild-type GUCY2D gene compared to cells that were not transfected with any sgRNAs (data not shown). Editing of wild-type GUCY2D cDNA using pAAV comprising SEQ ID NO: 5274 resulted in ~325 nM cGMP (data not shown).

[000953] These data provide evidence that the tested gRNAs can effectively edit a GUCY2D gene containing the R838H mutation regardless of whether the gRNAs are synthetic gRNAs (Figures 8A-B and 9A-B), or AAV-encoded gRNAs (Figures 10A-B). Additionally, these data provide evidence that gRNAs of the present disclosure can reduce protein expression from the GUCY2D gene in support of at least the NHEJ editing strategy (Figures 8-10).

Example 27 - Testing of guide RNAs in cells for off-target activity

[000954] To determine the extent of off-target editing on a genomic level, the gRNAs (or sgRNAs) having the best on-target activity will then be tested for targeted-genome-wide off- target editing using GUIDE-seq, Amplicon-seq, and/or Digenome-seq. Off-target effects will be tested in human cells. This testing can enable selection of gRNAs with increased specficity.

Example 28 - Testing different approaches for HDR gene editing

[000955] After testing the gRNAs for both on-target activity and off-target activity, mutation correction and knock-in strategies will be tested for HDR gene editing.

[000956] For the mutation correction approach, donor DNA template will be provided as a short single -stranded oligonucleotide, a short double-stranded oligonucleotide (PAM sequence intact/P AM sequence mutated), a long single -stranded DNA molecule (PAM sequence intact/PAM sequence mutated) or a long double -stranded DNA molecule (PAM sequence intact/PAM sequence mutated). In addition, the donor DNA template will be delivered by AAV.

[000957] For the cDNA knock-in approach, a single-stranded or double -stranded DNA having homologous arms to the GUCY2D chromosomal region can include more than 40 nt of the first exon (the first coding exon) of the GUCY2D gene, the complete CDS of the GUCY2D gene and 3’ UTR of the GUCY2D gene, and at least 40 nt of the following intron. The single-stranded or double-stranded DNA having homologous arms to the GUCY2D chromosomal region can include more than 80 nt of the first exon of the GUCY2D gene, the complete CDS of the GUCY2D gene and 3’ UTR of the GUCY2D gene, and at least 80 nt of the following intron.

The single-stranded or double -stranded DNA having homologous arms to the GUCY2D chromosomal region can include more than 100 nt of the first exon of the GUCY2D gene, the complete CDS of the GUCY2D gene and 3’ UTR of the GUCY2D gene, and at least 100 nt of the following intron. The single-stranded or double-stranded DNA having homologous arms to the GUCY2D chromosomal region can include more than 150 nt of the first exon of the

GUCY2D gene, the complete CDS of the GUCY2D gene and 3’ UTR of the GUCY2D gene, and at least 150 nt of the following intron. The single-stranded or double-stranded DNA having homologous arms to the GUCY2D chromosomal region can include more than 300 nt of the first exon of the GUCY2D gene, the complete CDS of the GUCY2D gene and 3’ UTR of the GUCY2D gene, and at least 300 nt of the following intron. The single-stranded or double- stranded DNA having homologous arms to the GUCY2D chromosomal region can include more than 400 nt of the first exon of the GUCY2D gene, the complete CDS of the GUCY2D gene and 3’ UTR of the GUCY2D gene, and at least 400 nt of the following intron.

[000958] Alternatively, the DNA template will be delivered by a recombinant AAV particle such as those taught herein. [000959] A knock-in of GUCY2D cDNA can be performed into any selected chromosomal location or in one of the“safe harbor” locus, i.e., albumin gene, an AAVS 1 gene, an HRPT gene, a CCR5 gene, a globin gene, TTR gene, TF gene, F9 gene, Alb gene, Gys2 gene and PCSK9 gene. Assessment of efficiency of HDR mediated knock-in of cDNA into the first exon can utilize cDNA knock-in into“safe harbor” sites such as: single-stranded or double-stranded DNA having homologous arms to one of the following regions, for example: AAVS1 19q 13.4- qter, HRPT lq3 l.2, CCR5 3p2l.3 l, Globin l lpl5.4, TTR l8ql2. l, TF 3q22. l, F9 Xq27. l, Alb 4ql3.3, Gys2 12p 12.1, PCSK9 lp32.3; 5 TJTR correspondent to GUCY2D or alternative 5’

UTR, complete CDS of GUCY2D and 3’ UTR of GUCY2D or modified 3’ UTR and at least 80 nt of the first intron, alternatively same DNA template sequence will be delivered by AAV.

[000960] These tests will allow for optimization of the various HDR gene editing strategies and comparisons based on their respective effectiveness will be made.

Example 29 - Re-assessment of lead CRISPR-Cas9/DNA donor combinations

[000961] After testing the different strategies for gene editing, the lead CRISPR-Cas9/DNA donor combinations will be re-assessed in cells for efficiency of deletion, recombination, and off-target specificity. Cas9 mRNA or RNP will be formulated into lipid nanoparticles for delivery, sgRNAs will be formulated into nanoparticles or delivered as a recombinant AAV particle, and donor DNA will be formulated into nanoparticles or delivered as recombinant AAV particle. These tests will allow for further optimization of the various HDR gene editing strategies.

Example 30 - Self-Inactivating (SIN) CRISPR-Cas Systems

[000962] When nucleic acids encoding Cas9 and/or guide RNA are delivered via viral vector, it can be advantageous to use a SIN vector to deliver at least one of the nucleic acids. Experiments were performed in order to further investigate the ability of various SIN vectors to edit targeted nucleic acids with specificity.

[000963] The three reporter cell lines described in Example 25 were used. The first reporter cell line has a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein (BFP) at the beta-tubulin gene locus. The second reporter cell line has a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a BFP at the beta-tubulin gene locus. The third reporter cell line has a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a BFP at the beta-tubulin gene locus. Thus, the Cas9 target site-BFP gene fusions comprised by the reporter cell lines can be used to report on editing activity at the Cas9 target site. The editing activity can cause loss of the BFP signal via a frameshift mutation. It was found that various combinations of Cas9 vectors and guide RNAs according to the present disclosure were effective in editing targeted GUCY2D R838H or R838C mutant Cas9 target sites. The various combinations were also specific such that editing of the wild-type GUCY2D Cas9 target sites was minimal and similar to background levels of BFP signal loss.

[000964] Each of the reporter cell lines was seeded in 2.5 ml of 10 % FBS/DMEM at 500,000 cells per well in 6-well plates at 24 hours before transfection.

[000965] Figure 12A shows results obtained when the reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg SIN-AAV SpCas9 ver. 1 (Figure 11A) and 1.25 pg pSIA0l2 (Figure 11D) using Lipofectamine® 3000. pSIA0l2 is a plasmid comprising an AAV sequence (SEQ ID NO: 5506) that encodes for R838H_Sp_T2 sgRNA (a sgRNA comprising SEQ ID NO: 5285) and EGFP. SIN-AAV SpCas9 ver. 1 encodes SpCas9 and includes SIN sites (also called R838 target sites) located 5’ (SEQ ID NO: 5478) and 3’ (SEQ ID NO: 5480) of the SpCas9 ORF. The 5’ SIN site (SEQ ID NO: 5478) in SIN-AAV SpCas9 ver. 1 comprises SEQ ID NO: 5327, which is targeted by sgRNA comprising SEQ ID NO: 5285. The 3’ SIN site (SEQ ID NO: 5480) in SIN-AAV SpCas9 ver. 1 comprises SEQ ID NO: 5369, which is also targeted by sgRNA comprising SEQ ID NO: 5285 (Table 9).

Table 9

SIN-AAV SpCas9 ver.l comprising two SIN sites targeted by a sgRNA comprising SEQ ID NO: 5285

[000966] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg SIN-AAV SpCas9 ver. 1 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 12C). [000967] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg SIN-AAV SpCas9 ver. 1 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 12E).

[000968] Figure 12B shows results obtained when the reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg SIN-AAV SpCas9 ver. 1 (Figure 11A) and 1.25 pg pSIA0l5 (Figure 11D) using Lipofectamine® 3000. pSIA0l5 is a plasmid comprising an AAV sequence (SEQ ID NO: 5507) that encodes for R838CH_Sp_Tl sgRNA (a sgRNA comprising SEQ ID NO: 5398) and EGFP. SIN-AAV SpCas9 ver. 1 encodes SpCas9 and includes SIN sites (also called R838 target sites) located 5’ (SEQ ID NO: 5478) and 3’ (SEQ ID NO: 5480) of the SpCas9 ORF. The 5’ SIN site (SEQ ID NO: 5478) in SIN-AAV SpCas9 ver. 1 comprises SEQ ID NO: 5326, which is targeted by sgRNA comprising SEQ ID NO: 5398. The 3’ SIN site (SEQ ID NO: 5480) in SIN-AAV SpCas9 ver. 1 comprises SEQ ID NO: 5368, which is targeted by sgRNA comprising SEQ ID NO: 5398 (Table 10).

Table 10

SIN-AAV SpCas9 ver.l comprising two SIN sites targeted by a sgRNA comprising SEQ ID NO: 5398

[000969] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg SIN-AAV SpCas9 ver. 1 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 12D).

[000970] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg SIN-AAV SpCas9 ver. 1 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 12F). [000971] Figure 12G shows results obtained when the reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg SIN-AAV SpCas9 ver. 2 (Figure 11B) and 1.25 pg pSIA0l2 (Figure 11D) using Lipofectamine® 3000. SIN-AAV SpCas9 ver. 2 encodes SpCas9 and includes SIN sites located 5’ (SEQ ID NO: 5479) and 3’ (SEQ ID NO: 5480) of the SpCas9 ORF. The 5’ SIN site (SEQ ID NO: 5479) in SIN-AAV SpCas9 ver. 2 comprises SEQ ID NO: 5327, which is targeted by sgRNA comprising SEQ ID NO: 5285. The 3’ SIN site (SEQ ID NO: 5480) in SIN-AAV SpCas9 ver. 2 comprises SEQ ID NO: 5369, which is targeted by sgRNA comprising SEQ ID NO: 5285 (Table 11).

Table 11

SIN-AAV SpCas9 ver.2 comprising two SIN sites targeted by a sgRNA comprising SEQ ID NO: 5285

[000972] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg SIN-AAV SpCas9 ver. 2 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 121).

[000973] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg SIN-AAV SpCas9 ver. 2 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 12K).

[000974] Figure 12H shows results obtained when the reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg SIN-AAV SpCas9 ver. 2 (Figure 11B) and 1.25 pg pSIA0l5 (Figure 11D) using Lipofectamine® 3000. SIN-AAV SpCas9 ver. 2 encodes SpCas9 and includes SIN sites located 5’ (SEQ ID NO: 5479) and 3’ (SEQ ID NO: 5480) of the SpCas9 ORF. The 5’ SIN site (SEQ ID NO: 5479) in SIN-AAV SpCas9 ver. 2 comprises SEQ ID NO: 5326, which is targeted by sgRNA comprising SEQ ID NO: 5398. The 3’ SIN site (SEQ ID NO: 5480) in SIN-AAV SpCas9 ver. 2 comprises SEQ ID NO: 5368, which is targeted by sgRNA comprising SEQ ID NO: 5398 (Table 12).

Table 12

SIN-AAV SpCas9 ver.2 comprising two SIN sites targeted by a sgRNA comprising SEQ ID NO: 5398

[000975] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg SIN-AAV SpCas9 ver. 2 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure

12J).

[000976] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg SIN-AAV SpCas9 ver. 2 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 12L).

[000977] Figure 12M shows results obtained when the reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg Non-SIN-AAV SpCas9 (Figure 11C) and 1.25 pg pSIA0l2 (Figure 11D) using Lipofectamine® 3000. Non-SIN-AAV SpCas9 encodes SpCas9 and includes no SIN sites (also called R838 target sites).

[000978] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg Non-SIN-AAV SpCas9 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 12P).

[000979] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with

1.25 pg Non-SIN-AAV SpCas9 and 1.25 pg pSIA0l2 using Lipofectamine® 3000 (Figure 12S).

[000980] Figure 12N shows results obtained when the reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 mg Non-SIN-AAV SpCas9 (Figure 11C) and 1.25 pg pSIA0l5 (Figure 11D) using Lipofectamine® 3000.

[000981] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg Non-SIN-AAV SpCas9 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 12Q).

[000982] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with 1.25 pg Non-SIN-AAV SpCas9 and 1.25 pg pSIA0l5 using Lipofectamine® 3000 (Figure 12T).

[000983] The reporter cell line having a wild-type GUCY2D gene (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with only transfection reagent (no DNA) using Lipofectamine® 3000 (Figure 120).

[000984] The reporter cell line having a GUCY2D gene comprising a R838H mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with only transfection reagent (no DNA) using Lipofectamine® 3000 (Figure 12R).

[000985] The reporter cell line having a GUCY2D gene comprising a R838C mutation (Cas9 target site) fused to a blue fluorescent protein at the beta-tubulin gene locus was transfected with only transfection reagent (no DNA) using Lipofectamine® 3000 (Figure 12U).

[000986] At 72 hours post-transfection, reporter cells were dissociated from the plates by incubation with trypsin-EDTA, and analyzed for blue fluorescence (BFP) and green fluorescence (GFP) by flow cytometry. A frame-shift induced by genome editing at a Cas9 target site (whether the Cas9 target site is the wild-type GUCY2D gene, the GUCY2D gene comprising the R838H mutation, or the GUCY2D gene comprising the R838C mutation) of the HEK 293FT cell results in loss of BFP. EGFP and sgRNA are encoded on the same vector and the EGFP serves as a transfection marker. Therefore, HEK 293FT cells transfected with pSIA0l2 (which comprises an AAV sequence that encodes R838H_Sp_T2 sgRNA - a sgRNA comprising SEQ ID NO: 5285) or pSIA0l5 (which comprises an AAV sequence that encodes R838CH_Sp_Tl sgRNA - a sgRNA comprising SEQ ID NO: 5398) are GFP positive.

[000987] Gene editing in the transfected cells was estimated in the cell populations plotted within a gate (Figures 12A-12U). The bolded percentages in Figures 12A-12U indicate BFP negative and GFP positive cells within the gate. BFP negative means that gene editing occurred at the Cas9 target site of these transfected HEK 293FT cells. GFP positive means that these transfected HEK 293FT cells contain a plasmid that encodes EGFP and sgRNA. [000988] Figure 12A shows that of the transfected HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site in the gate, 9.63% of these cells had the wild- type GUCY2D gene edited when transfected with SIN-AAV SpCas9 ver. 1 and pSIA0l2, which encodes R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285).

[000989] Figure 12B shows that of the transfected HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site in the gate, ~0% of these cells had the wild-type GUCY2D gene edited when transfected with SIN-AAV SpCas9 ver. 1 and pSIA0l5, which encodes R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398).

[000990] Figure 12C shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site in the gate, 53.07% of these cells had the R838H mutation edited when transfected with SIN-AAV SpCas9 ver. 1 and pSIA0l2.

[000991] Figure 12D shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site in the gate, 21.04% of these cells had the R838H mutation edited when transfected with SIN-AAV SpCas9 ver. 1 and pSIA0l5.

[000992] Figure 12E shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site in the gate, ~0% of these cells had the R838C mutation edited when transfected with SIN-AAV SpCas9 ver. 1 and pSIA0l2.

[000993] Figure 12F shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site in the gate, 26.35% of these cells had the R838C mutation edited when transfected with SIN-AAV SpCas9 ver. 1 and pSIA0l5.

[000994] Figure 12G shows that of the transfected HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site in the gate, 7.43% of these cells had the wild- type GUCY2D gene edited when transfected with SIN-AAV SpCas9 ver. 2 and pSIA0l2.

[000995] Figure 12H shows that of the transfected HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site in the gate, ~0% of these cells had the wild-type GUCY2D gene edited when transfected with SIN-AAV SpCas9 ver. 2 and pSIA0l5.

[000996] Figure 121 shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site in the gate, 52.62% of these cells had the R838H mutation edited when transfected with SIN-AAV SpCas9 ver. 2 and pSIA0l2.

[000997] Figure 121 shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site in the gate, 18.50% of these cells had the R838H mutation edited when transfected with SIN-AAV SpCas9 ver. 2 and pSIA0l5. [000998] Figure 12K shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site in the gate, ~0% of these cells had the R838C mutation edited when transfected with SIN-AAV SpCas9 ver. 2 and pSIA0l2.

[000999] Figure 12L shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site in the gate, 24.73% of these cells had the R838C mutation edited when transfected with SIN-AAV SpCas9 ver. 2 and pSIA0l5.

[0001000] Figure 12M shows that of the transfected HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site in the gate, 13.51% of these cells had the wild- type GUCY2D gene edited when transfected with Non-SIN-AAV SpCas9 and pSIA0l2.

[0001001] Figure 12N shows that of the transfected HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site in the gate, ~0% of these cells had the wild-type GUCY2D gene edited when transfected with Non-SIN-AAV SpCas9 and pSIA0l5.

[0001002] Figure 120 shows that of the transfected HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site in the gate, 0% of these cells had the wild-type GUCY2D gene edited when no DNA was used.

[0001003] Figure 12P shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site in the gate, 50.34% of these cells had the R838H mutation edited when transfected with Non-SIN-AAV SpCas9 and pSIA0l2.

[0001004] Figure 12Q shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site in the gate, 20.62% of these cells had the R838H mutation edited when transfected with Non-SIN-AAV SpCas9 and pSIA0l5.

[0001005] Figure 12R shows that of the transfected HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site in the gate, 0% of these cells had the R838H mutation edited when no DNA was used.

[0001006] Figure 12S shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site in the gate, ~0% of these cells had the R838C mutation edited when transfected with Non-SIN-AAV SpCas9 and pSIA0l2.

[0001007] Figure 12T shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site in the gate, 29.17% of these cells had the R838C mutation edited when transfected with Non-SIN-AAV SpCas9 and pSIA0l5.

[0001008] Figure 12U shows that of the transfected HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site in the gate, 0% of these cells had the R838C mutation edited when no DNA was used. [0001009] Since no genome editing was induced in mock transfected cells, the vast majority of mock transfected cells are BFP positive (Figures 120, 12R, and 12U).

[0001010] The results reported in Figures 12A-U provide evidence that the SIN vectors of the present disclosure can edit genomic target alleles with specificity.

[0001011] To determine the ability of SIN vectors to limit Cas9 expression, the expression levels of Cas9 protein were measured by immunoblot (Figures 13A-C) for the cells used in the experiments described by Figures 12A-U.

[0001012] At 72 hours post-transfection, reporter cells were also harvested in PBS, and total protein was extracted in 0.1 % Triton X-100/TBS (25 mM Tris-HCl (pH 7.5) and 150 mM NaCl). Five micrograms of total protein was separated on NUPAGE 4-12 %

polyacrylamide/Tris-Bis gels, and transferred onto nitrocellulose membranes. SpCas9, EGFP (as a transfection control) and beta actin (as an internal control) were detected using a Cas9 monoclonal antibody, GFP Tag polyclonal antibody, and beta actin loading control monoclonal antibody, respectively.

[0001013] Figure 13A (lane 1) shows Cas9 inactivation in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that were transfected with SIN -AAV SpCas9 ver. 1 (Figure 11A) and pSIA0l2, which encodes R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285).

[0001014] Figure 13A (lane 2) shows Cas9 inactivation in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that were transfected with SIN -AAV SpCas9 ver. 2 (Figure 11B) and pSIA0l2.

[0001015] Figure 13A (lane 3) shows Cas9 expression in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that were transfected with Non-SIN- AAV SpCas9 (Figure 11C) and pSIA0l2.

[0001016] Figure 13A (lane 4) shows no Cas9 expression in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that were not transfected with any DNA.

[0001017] Figure 13A (lane 5) shows Cas9 inactivation in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that were transfected with SIN -AAV SpCas9 ver. 1 (Figure 11A) and pSIA0l5, which encodes R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398).

[0001018] Figure 13A (lane 6) shows Cas9 inactivation in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that were transfected with SIN -AAV SpCas9 ver. 2 (Figure 11B) and pSIA0l5. [0001019] Figure 13A (lane 7) shows Cas9 expression in HEK 293FT reporter cells that have the wild-type GUCY2D gene as the Cas9 target site and that were transfected with Non-SIN- AAV SpCas9 (Figure 11C) and pSIA0l5.

[0001020] Figure 13B (lane 1) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

1 (Figure 11A) and pSIA0l2, which encodes R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285).

[0001021] Figure 13B (lane 2) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

2 (Figure 11B) and pSIA0l2.

[0001022] Figure 13B (lane 3) shows Cas9 expression in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that were transfected with Non-SIN-AAV SpCas9 (Figure 11C) and pSIA0l2.

[0001023] Figure 13B (lane 4) shows no Cas9 expression in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that were not transfected with any DNA.

[0001024] Figure 13B (lane 5) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

1 (Figure 11A) and pSIA0l5, which encodes R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398).

[0001025] Figure 13B (lane 6) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

2 (Figure 11B) and pSIA0l5.

[0001026] Figure 13B (lane 7) shows Cas9 expression in HEK 293FT reporter cells that have the R838H mutation as the Cas9 target site and that were transfected with Non-SIN-AAV SpCas9 (Figure 11C) and pSIA0l5.

[0001027] Figure 13C (lane 1) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

1 (Figure 11A) and pSIA0l2, which encodes R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285).

[0001028] Figure 13C (lane 2) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

2 (Figure 11B) and pSIA0l2. [0001029] Figure 13C (lane 3) shows Cas9 expression in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that were transfected with Non-SIN-AAV SpCas9 (Figure 11C) and pSIA0l2.

[0001030] Figure 13C (lane 4) shows no Cas9 expression in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that were not transfected with any DNA.

[0001031] Figure 13C (lane 5) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

1 (Figure 11A) and pSIA0l5, which encodes R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398).

[0001032] Figure 13C (lane 6) shows Cas9 inactivation in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that were transfected with SIN-AAV SpCas9 ver.

2 (Figure 11B) and pSIA0l5.

[0001033] Figure 13C (lane 7) shows Cas9 expression in HEK 293FT reporter cells that have the R838C mutation as the Cas9 target site and that were transfected with Non-SIN-AAV SpCas9 (Figure 11C) and p SI A015.

[0001034] To confirm that introduced SIN sites do not influence transcription and translation of Cas9, HEK 293FT cells were transfected with 1.25 pg of pDLl07 (which encodes GFP and does not encode sgRNA) and either (1) SIN-AAV SpCas9 ver. 1, (2) SIN-AAV SpCas9 ver. 2, or (3) Non-SIN-AAV SpCas9. Cells were seeded in 2.5 ml of 10 % FBS/DMEM at 500,000 cells per well in 6-well plates at 24 hours before transfection. At 72 hours after transfection, GFP expression of all the transfected cells were analyzed by flow cytometry, and total protein was extracted in 0.1 % Triton X-100/TBS (25 mM Tris-HCl (pH 7.5) and 150 mM NaCl). Five micrograms of total protein was separated on a NUPAGE 4-12 % polyacrylamide/Tris-Bis gel, and transferred onto nitrocellulose membranes. SpCas9, EGFP (as a transfection control) and beta actin (as an internal control) were detected using a Cas9 monoclonal antibody, GFP Tag polyclonal antibody and beta actin loading control monoclonal antibody, respectively. Results showed that there was equal SpCas9 expression in HEK 293FT cells transfected with (1) SIN- AAV SpCas9 ver. 1, (2) SIN-AAV SpCas9 ver. 2, and (3) Non-SIN-AAV SpCas9 (Data not shown).

[0001035] SIN Cas9 vectors showed decreased expression of Cas9 in all three reproter cell lines when targeted by either a guide RNA comprising SEQ ID NO: 5285 or 5398, thus providing evidence that SIN vectors of the present disclosure can limit expression of Cas9 protein (Figures 13A-C), while still causing editing oftartgeted alleles (Figures 12A-U). Example 31 - Self-Inactivating (SIN) CRISPR-Cas Systems

[0001036] To determine the ability of SIN vectors to limit Cas9 expression in vivo, the expression levels of Cas9 protein were measured by immunoblot in mouse retinas isolated 28 days after subretinal AAV injection (Figures 15A-B).

[0001037] Eight to ten-week-old C57BL/6J mice were purchased from Jackson Laboratories and maintained at MisoPro Animal Facility (Cambridge, MA). All animal procedures were conducted in compliance with the Animal Welfare Act, and the Guide for the Care and Use of Laboratory Animals, the Office of Laboratory Animal Welfare and in accordance with the Association for Research in Vision and Ophthalmology (ARVO) Statement for the Use of Animals in Ophthalmic and Vision Research.

[0001038] AAVs were delivered by subretinal injection [2 xlO ⁹ genome copies (GC) for each vector] into the wild-type mice following standard subretinal injection procedure. There were 10 different AAV groups delivered by subretinal injection. The first group included: SIN-AAV SpCas9 ver. 1 (Figure 14A), AAV-R838H_Sp_T2 sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. Figure 11D shows the structural arrangement of an AAV sequence located within pSIA0l2, a plasmid that is used to generate AAV-R838H_Sp_T2 sgRNA. AAV-R838H_Sp_T2 sgRNA encodes a sgRNA comprising SEQ ID NO: 5285. The second group included: SIN-AAV SpCas9 ver. 2 (Figure 14B), AAV-R838H_Sp_T2 sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. The third group included: Non-SIN-AAV SpCas9 (Figure 14C), AAV-R838H_Sp_T2 sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. The fourth group included: AAV- R838H_Sp_T2 sgRNA and an AAV comprising a R838H mutation within the GUCY2D gene. The fifth group included: AAV-R838H_Sp_T2 sgRNA. The sixth group included: SIN-AAV SpCas9 ver. 1 (Figure 14A), AAV R838CH_Sp_Tl sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. Figure 11D shows the structural arrangement of an AAV sequence located within pSIA0l5, a plasmid that is used to generate AAV-R838CH_Sp_Tl sgRNA. AAV-R838CH_Sp_Tl sgRNA encodes a sgRNA comprising SEQ ID NO: 5398. The seventh group included: SIN-AAV SpCas9 ver. 2 (Figure 14B), AAV R838CH_Sp_Tl sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. The eighth group included: Non-SIN-AAV SpCas9 (Figure 14C), AAV R838CH_Sp_Tl sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. The ninth group included: AAV R838CH_Sp_Tl sgRNA and an AAV comprising a R838H mutation within the GUCY2D gene. The tenth group included: AAV R838CH_Sp_Tl sgRNA. [0001039] On Day 28 post AAV injection, mouse retinas were isolated using micro-dissecting scissors under a dissection microscope. The retinal pigment epithelium (RPE) layer was carefully removed. Cells were lysed in RIPA lysis buffer (Thermo Fisher Scientific) supplemented with Halt Protease Inhibitor cocktail on ice. Protein quantification was measured by Pierce BCA assay (Thermo Fisher Scientific).

[0001040] Protein per retina sample was separated using the NuPAGE Electrophoresis System (Thermo Fisher Scientific), after which the proteins were transferred using 0.45um Pore Size Nitrocellulose Membrane Filter Paper Sandwich (Thermo Fisher Scientific). Blocking buffer with Pierce TBST (Tris-buffered saline with Tween 20 detergent) buffer containing 5% (w/v) BSA was prepared. Membranes were blocked by Pierce TBST (Tris-buffered saline with Tween 20 detergent) buffer containing 5% (w/v) BSA at room temperature for 2 hours, or 4 °C overnight. The membranes were then incubated with a primary antibody by diluting the antibody with blocking buffer and incubating the membrane on a rocker at 4 °C overnight. After three washes, the membrane was incubated with secondary antibodies at 1:5000 at RT for 1 hour. Imaging was obtained with ChemiDoc™ MP Imaging System (BioRad).

[0001041] Figure 15A (lanes 1-2) shows Cas9 inactivation in retinas (without RPE) that were transfected with SIN-AAV SpCas9 ver. 1, AAV R838H_Sp_T2 sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene.

[0001042] Figure 15A (lanes 3-4) shows Cas9 inactivation in retinas (without RPE) that were transfected with SIN-AAV SpCas9 ver. 2, AAV R838H_Sp_T2 sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene.

[0001043] Figure 15A (lanes 5-6) shows Cas9 expression in retinas (without RPE) that were transfected with Non-SIN-AAV SpCas9, AAV R838H_Sp_T2 sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene.

[0001044] Figure 15A (lanes 7-8) shows no Cas9 expression in retinas (without RPE) that were transfected with AAV R838H_Sp_T2 sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene.

[0001045] Figure 15A (lanes 9-10) shows no Cas9 expression in retinas (without RPE) that were transfected with only AAV R838H_Sp_T2 sgRNA.

[0001046] Figure 15B (lanes 1-2) shows Cas9 inactivation in retinas (without RPE) that were transfected with SIN-AAV SpCas9 ver. 1, AAV R838CH_Sp_Tl sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. [0001047] Figure 15B (lanes 3-4) shows Cas9 inactivation in retinas (without RPE) that were transfected with SIN-AAV SpCas9 ver. 2, AAV R838CH_Sp_Tl sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene.

[0001048] Figure 15B (lanes 5-6) show Cas9 expression in retinas (without RPE) that were transfected with Non-SIN-AAV SpCas9, AAV R838CH_Sp_Tl sgRNA, and an AAV comprising a R838H mutation within the GUCY2D gene. Figure 15B (lane 6) shows a fainter Cas9 band than in lane 5, but the Cas9 band is still present. The retina in lane 6 was not transduced as well as the retina in lane 5. In fact the band for GFP is also fainter in lane 6 compared to lane 5 further demonstrating that the retina in lane 6 was not transduced as well as the retina in lane 5.

[0001049] Figure 15B (lanes 7-8) shows no Cas9 expression in retinas (without RPE) that were transfected with AAV R838CH_Sp_Tl sgRNA and an AAV comprising a R838H mutation within the GUCY2D gene.

[0001050] Figure 15B (lanes 9-10) shows no Cas9 expression in retinas (without RPE) that were transfected with only AAV R838CH_Sp_Tl sgRNA.

[0001051] As discussed above, two versions of self-inactivating (SIN) AAV vectors that limit their own expression of Cas9 after transfection were created. Examples of version 1 vectors are depicted in Figures 11A and 14A. Examples of version 2 vectors are depicted in Figures 11B and 14B. Both version 1 and version 2 vectors comprise two SIN sites (also called R838 target sites), which are vulnerable to cutting by Cas9-sgRNA RNPs. Cas9-mediated double strand breaks at one of these sites could lead to removal of either a promoter or polyadenylation signal in the Cas9 gene. Cas9-mediated double strand breaks at both of these sites occurring contemporaneously could lead to deletion of the Cas9 gene. Both possibilities (e.g., 1 or 2 DSBs) would inhibit Cas9 expression.

[0001052] It has been observed that version 1 vectors lead to more efficient self-inactivation than version 2 vectors (Figure 15B). Version 1 vectors comprise a 5’ SIN site (R838 target site) that is located upstream of the Cas9 open reading frame (ORF) and downstream of a SV40 nuclear localization signal (NLS). Version 2 vectors comprise a 5’ SIN site (R838 target site) that is located upstream of the Cas9 open reading frame (ORF) and upstream of a SV40 nuclear localization signal (NLS) within a 5’ untranslated region (UTR). In a version 1 vector, mutations resulting from non-homologous end-joining could create frame-shifts, which cause introduction of premature stop codons in the Cas9 gene ORF. In a version 2 vector, such mutations would be unlikely to create such changes in the Cas9 ORF since the SIN site (R838 target site) is in the 5’ UTR, outside of the ORF. These mutations could still disrupt transcription initiation, but their overall effect on Cas9 expression is likely to be less than the mutations in a version 1 vector. Furthermore, once a mutation is created in either vector, a second is unlikely since the site will no longer share sufficient homology with the sgRNA spacer sequence for efficient additional editing. For at least these reasons, there is a disparity in SIN efficiency observed between the two vector versions.

[0001053] SIN Cas9 vectors showed decreased expression of Cas9 when targeted by either a guide RNA comprising SEQ ID NO: 5285 or 5398, thus providing evidence that SIN vectors of the present disclosure can limit expression of Cas9 protein in vivo.

Example 32 - Testing of guide RNAs in cells for on-target activity

[0001054] To further evaluate the specificity of gRNAs povided herein, selected gRNAs were further tested for on-target activity in immortalized human patient-derived fibroblasts that have a R838H mutant allele as a copy of the GUCY2D gene.

[0001055] Patients with a R838H mutant allele provided skin biopsies to create an immortalized cell line. Primary fibroblasts were isolated from these biopsies and cultured in 10% FBS/DMEM supplemented with GlutaMAX™, a supplement comprising an L-alanyl-L-glutamine dipeptide in 0.85% NaCl manufactured by Thermo Fisher Scientific, Massachusetts, US. GlutaMAX™ is. Immortalization of patient-derived fibroblasts was conducted by the Natural and Medical Sciences Institute at the University of Tiibingen, Germany. The immortalized patient-derived fibroblasts were cultured in 10% FBS/DMEM supplemented with GlutaMAX™ and passaged every 3-4 days.

[0001056] A plasmid, pSpCas9 (BB)-2A-miRFP670 (“pSpCas9”) (SEQ ID NO: 5512), was obtained (Addgene: Watertown, Massachusetts). The pSpCas9 sequence contains a CMV promoter-driven SpCas9 gene, SV40 polyadenylation signal, 2A linker peptide, and miRFP670. The 2A linker peptide is located on the plasmid between the SpCas9 gene and miRFP670 and is cleaved after translation. Therefore, if the SpCas9 gene is transcribed and translated, then RFP is also transcribed and translated.

[0001057] pSIA0l2 (SEQ ID NO: 5469), depicted in Figure 11D, comprises a sequence that encodes for a U6 promoter driven R838H_Sp_T2 sgRNA (a sgRNA comprising SEQ ID NO: 5285) and CMV promoter driven EGFP. [0001058] pSIA0l5 (SEQ ID NO: 5471), depicted in Figure 11D, comprises a sequence that encodes for a U6 promoter driven R838CH_Sp_Tl sgRNA (a sgRNA comprising SEQ ID NO: 5398) and CMV promoter driven EGFP.

[0001059] As described in Example 24, pSIA003 is a plasmid that can encode a U6 driven gRNA sequence depending on the gRNA sequence that is cloned into the plasmid. For this particular experiment, the pSIA003 that was used comprises a sequence that encodes for a U6 promoter driven non-targeting (e.g., scrambled) sgRNA that does not target the R838H mutant allele. The non-targeting sgRNA comprises SEQ ID NO: 5513. pSIA003 also comprises a sequence that encodes a CMV promoter driven EGFP.

[0001060] Immortalized patient-derived fibroblasts comprising a R838H mutant allele were seeded in 2.5 ml of 10% FBS/DMEM supplemented with GlutaMAX™ at 500,000 cells per well in 6-well plates 24 hours before transfection via electroporation.

[0001061] The immortalized patient-derived fibroblast cells were transfected with 10 pg of pSpCas9 and 1 pg of either: pSIA0l2, pSIA0l5, or pSIA003, using a NEON™ electroporation system (available from Thermo Fisher Scientific, Massachusetts, US).

[0001062] At 48 hours post-transfection, immortalized patient-derived fibroblast cells were dissociated from the plates by incubation with trypsin-EDTA, and analyzed for red fluorescence (RFP) and green fluorescence (GFP) by flow cytometry. Each of the three plasmids that encodes the sgRNAs used in this Example encodes EGFP, and the EGFP serves as a transfection marker. Immortalized patient-derived fibroblasts transfected with pSIA0l2, pSIA0l5, or pSIA003 are GFP positive. RFP and SpCas9 are encoded on the same plasmid and the RFP serves as a transfection marker. Immortalized patient-derived fibroblasts transfected with pSpCas9 are RFP positive.

[0001063] Immortalized patient-derived fibroblasts that are GFP+ RFP+ are cells that were successfully transfected with one of the three sgRNA plasmids (pSIA0l2, pSIA0l5, or pSIA003) and also with pSpCas9. Genomic DNA was extracted from sorted GFP+ RFP+ cells. Indels were analyzed by TIDE to determine editing efficiency in the immortalized patient-derived fibroblasts transfected with pSpCas9 and either pSIA0l2 (Figure 16, sample 1), pSIA0l5 (Figure 16, sample 2), or pSIA003 (Figure 16, sample 3).

[0001064] Figure 16, sample 1 shows that of the GFP+RFP+ transfected immortalized patient- derived fibroblasts that have the R838H mutant allele, 33.9 + 10.8% of these cells had the R838H mutant allele edited when R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO:

5285) was used as the sgRNA. The 33.9 + 10.8% editing efficiency was the result of three separate experiments that included immortalized patient derived fibroblasts from two separate patients. Patient # Us fibroblasts were used in two experiments and Patent #2’s fibroblasts were used in one experiment. Two different patients showed consistent -40% editing in spite of variability that can be seen from one patient to the next. This suggests that a gRNA or sgRNA comprising SEQ ID NO: 5285 consistently edits the R838H mutant allele.

[0001065] Figure 16, sample 2 shows that of the GFP+RFP+ transfected immortalized patient- derived fibroblasts that have the R838H mutant allele, 15.5 + 8.9% of these cells had the R838H mutant allele edited when R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) was used as the sgRNA.

[0001066] Figure 16, sample 3 shows that of the GFP+RFP+ transfected immortalized patient- derived fibroblasts that have the R838H mutant allele, 1.15 + 0.3% of these cells had the R838H mutant allele edited when a non-targeting (e.g., scrambled) sgRNA that does not target the R838H mutant allele was used as the sgRNA. This sample served as a negative control.

[0001067] These data (presented in Figure 16) provide evidence that sgRNAs of the present disclosure can effectively edit the mutant R838H GUCY2D gene in human cells.

Example 33 - Testing of guide RNAs in cells for on-target activity

[0001068] To further evaluate the specificity of gRNAs provided herein, selected gRNAs were further tested for on-target activity in immortalized human patient-derived fibroblasts that have a R838C mutant allele as a copy of the GUCY2D gene.

[0001069] Patients with a R838C mutant allele provided skin biopsies to create an immortalized cell line. Primary fibroblasts were isolated from these biopsies and cultured in 10% FBS/DMEM supplemented with GlutaMAX™. Immortalization of patient-derived fibroblasts was conducted by the Natural and Medical Sciences Institute at the University of Tiibingen, Germany. The immortalized patient-derived fibroblasts were cultured in 10% FBS/DMEM supplemented with GlutaMAX™ and passaged every 3-4 days.

[0001070] Immortalized patient-derived fibroblasts comprising a R838C mutant allele were seeded in 2.5 ml of 10% FBS/DMEM supplemented with GlutaMAX™ at 500,000 cells per well in 6-well plates 24 hours before transfection via electroporation.

[0001071] The immortalized patient-derived fibroblast cells were transfected with 10 pg of pSpCas9 and 1 pg of either: pSIA0l2, pSIA0l5, or pSIA003, using a NEON™ electroporation system (available from Thermo Fisher Scientific, Massachusetts, US). [0001072] At 48 hours post-transfection, immortalized patient-derived fibroblast cells were dissociated from the plates by incubation with trypsin-EDTA, and analyzed for red fluorescence (RFP) and green fluorescence (GFP) by flow cytometry. Each of the three plasmids that encodes the sgRNAs used in this Example encodes EGFP, and the EGFP serves as a transfection marker. Immortalized patient-derived fibroblasts transfected with pSIA0l2, pSIA0l5, or pSIA003 are GFP positive. RFP and SpCas9 are encoded on the same plasmid and the RFP serves as a transfection marker. Immortalized patient-derived fibroblasts transfected with pSpCas9 are RFP positive.

[0001073] Immortalized patient-derived fibroblasts that are GFP+ RFP+ are cells that were successfully transfected with one of the three sgRNA plasmids (pSIA0l2, pSIA0l5, or pSIA003) and also with pSpCas9. Genomic DNA was extracted from sorted GFP+ RFP+ cells. Indels were analyzed by TIDE to determine editing efficiency in the immortalized patient-derived fibroblasts transfected with pSpCas9 and either pSIA0l2 (Figure 17, sample 1), pSIA0l5 (Figure 17, sample 2), or pSIA003 (Figure 17, sample 3).

[0001074] Figure 17, sample 1 shows that of the GFP+RFP+ transfected immortalized patient- derived fibroblasts that have the R838C mutant allele, 10.98 + 2.6% of these cells had the R838C mutant allele edited when R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) was used as the sgRNA.

[0001075] Figure 17, sample 2 shows that of the GFP+RFP+ transfected immortalized patient- derived fibroblasts that have the R838C mutant allele, 34.15 + 0.6% of these cells had the R838C mutant allele edited when R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) was used as the sgRNA.

[0001076] Figure 17, sample 3 shows that of the GFP+RFP+ transfected immortalized patient- derived fibroblasts that have the R838C mutant allele, 8.75 + 6.9% of these cells had the R838C mutant allele edited when a non-targeting (e.g., scrambled) sgRNA that does not target the R838C mutant allele was used as the sgRNA. This sample served as a negative control.

[0001077] These data (presented in Figure 17) provide evidence that sgRNAs of the present disclosure can effectively edit the mutant R838C GUCY2D gene in human cells.

Example 34 - Testing of guide RNAs in cells for off-target activity

[0001078] To further evaluate the specificity of gRNAs provided herein, selected gRNAs were further tested for off-target activity in BJ-5TA HDF cells, which are hTERT-immortalized human fibroblast cells that are homozygous for the wild-type copy of the GUCY2D gene (“wild- type fibroblasts”).

[0001079] Wild-type fibroblasts were obtained (as ATCC® CRL-4001™ from ATCC, Manassas, Virginia) and were cultured in a 4: 1 mixture of supplemented DMEM and Medium 199 and passaged every 3-4 days. DMEM was suppplemented with 4 mM L-glutamine, 4.5 g/L glucose, and 1.5 g/L sodium bicarbonate. Medium 199 was supplemented with 0.01 mg/mL hygromycin B and 10% FBS.

[0001080] pSpCas9, pSIA0l2, pSIA0l5, and pSIA003, previously described in Example 32 were used in this experiment. pSIA022 was also used. pSIA022 (SEQ ID NO: 5514), comprises a sequence that encodes for a U6 promoter driven WT_Tl_sgRNA (a sgRNA comprising SEQ ID NO: 5274) and CMV promoter driven EGFP.

[0001081] Wild-type fibroblasts were seeded in 2.5 ml of the 4: 1 mixture of supplemented DMEM and Medium 199 at 500,000 cells per well in 6-well plates 24 hours before transfection via electroporation.

[0001082] Wild-type fibroblasts were transfected with 10 pg of pSpCas9 and 1 pg of either: pSIA0 l2, pSIA0l5, pSIA022, or pSIA003, using a NEON™ electroporation system (available from Thermo Fisher Scientific, Massachusetts, US).

[0001083] At 48 hours post-transfection, wild-type fibroblasts were dissociated from the plates by incubation with trypsin-EDTA, and analyzed for red fluorescence (RFP) and green fluorescence (GFP) by flow cytometry. Each of the four plasmids that encodes the sgRNAs used in this Example encodes EGFP, and the EGFP serves as a transfection marker. Wild-type fibroblasts transfected with pSIA0l2, pSIA0l5, pSIA022, or pSIA003 are GFP positive. RFP and SpCas9 are encoded on the same plasmid and the RFP serves as a transfection marker. Wild-type fibroblasts transfected with pSpCas9 are RFP positive.

[0001084] Wild-type fibroblasts that are GFP+ RFP+ are cells that were successfully transfected with one of the four sgRNA plasmids (pSIA0l2, pSIA0l5, pSIA022, or pSIA003) and also with pSpCas9. Genomic DNA was extracted from sorted GFP+ RFP+ cells. Indels were analyzed by TIDE to determine editing efficiency in the wild-type fibroblasts transfected with pSpCas9 and either pSIA0l2 (Figure 18, sample 1), pSIA0l5 (Figure 18, sample 2), pSIA022 (Figure 18, sample 3), or pSIA003 (Figure 18, sample 4).

[0001085] Figure 18, sample 1 shows that of the GFP+RFP+ transfected wild-type fibroblasts, 9.3 + 6.0% of these cells had the wild-type GUCY2D allele edited when R838H_Sp_T2 sgRNA (sgRNA comprising SEQ ID NO: 5285) was used as the sgRNA. [0001086] Figure 18, sample 2 shows that of the GFP+RFP+ transfected wild-type fibroblasts,

1.9 + 0.7% of these cells had the wild-type GUCY2D allele allele edited when R838CH_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5398) was used as the sgRNA.

[0001087] Figure 18, sample 3 shows that of the GFP+RFP+ transfected wild-type fibroblasts, 79.7 + 12.7% of these cells had the wild-type GUCY2D allele allele edited when WT_Sp_Tl sgRNA (sgRNA comprising SEQ ID NO: 5274) was used as the sgRNA. This sample served as a postive control.

[0001088] Figure 18, sample 4 shows that of the GFP+RFP+ transfected wild-type fibroblasts,

1.8 + 0.3% of these cells had the wild-type GUCY2D allele edited when a non-targeting (e.g., scrambled) sgRNA that does not target the wild-type GUCY2D allele was used as the sgRNA. This sample served as a negative control.

[0001089] These data provide evidence that sgRNAs of the present disclosure can have minimal off-target activity in human cells. [0001090] Note Regarding Illustrative Examples

[0001091] While the present disclosure provides descriptions of various specific aspects for the purpose of illustrating various examples of the present disclosure and/or its potential applications, it is understood that variations and modifications will occur to those skilled in the art. Accordingly, the invention or inventions described herein should be understood to be at least as broad as they are claimed, and not as more narrowly defined by particular illustrative examples provided herein.