METHODS OF DETECTING AMINO ACID DEFICIENCIES PRIORITY AND CROSS-REFERENCE TO RELATED TO APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application 62/916122 filed on October 16, 2019, which is hereby incorporated by reference in its entirety. SEQUENCE LISTING AND TABLES IN ELECTRONIC FORMAT [0002] The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing is provided as a file entitled PNDRI012WOSEQLIST, created October 14, 2020, which is 67,779 bytes in size. The information in the electronic format of the Sequence Listing is incorporated herein by reference in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED R&D [0003] This invention was made with government support from the National Instituted of Health/National Institute of General Medical Sciences under grant number R01 GM134274. The government has certain rights in the invention. Field [0004] Methods of determining amino acid deficiencies in a subject, such as a developing fetus or an asymptomatic subject. Also contemplated are methods for predicting genetic outcome of progeny that is directed to probability of metabolic diseases. Method of therapy and kits are also provided. Also described herein are methods for codon harmonization in which the codons of a heterologous protein coding sequence are altered to more closely match the usage frequency of the codons in orthologous positions of the host organism’s orthologous gene, even if the amino acids encoded at those position differ between the two orthologs. BACKGROUND [0005] Loss of function mutations in the genes encoding metabolic enzymes, including those responsible for the biosynthesis of serine, arginine, or other amino acids, can cause a class of human diseases collectively known as Inborn Errors of Metabolism. [0006] Neu-Laxova syndrome (NLS) is a rare genetic disorder that is inherited as an autosomal recessive trait. The syndrome is characterized by severe growth delays that occur before birth. Intrauterine growth retardation, low birth weight and length, and distinctive abnormalities of the head and facial (craniofacial) region are some of the symptoms of this disorder. Other characteristics may include a marked smallness of the head (microcephaly), sloping of the forehead, widely spaced eyes (ocular hypertelorism), and other malformations, resulting in a distinctive facial appearance. Abnormal accumulations of fluid in tissues throughout the body (generalized edema), permanent flexion and immobilization of multiple joints (flexion contractures), limb malformations and/or abnormalities of the brain, skin, genitals, kidneys, and/or heart may also be found in those suffering from Neu-Laxova syndrome (NLS). (Scott et. al; Am J Med Genet.1981;9:165-75; included by reference) [0007] In newborns additional physical abnormalities may also be present, such as underdevelopment of the genitals, the absence of one of the kidneys (unilateral renal agenesis) or other renal defects, underdevelopment of the lungs (pulmonary hypoplasia), or structural abnormalities of the heart (congenital heart defects). Congenital cardiac malformations may include an abnormal opening in the fibrous partition (septum) that separates the upper or lower chambers of the heart (atrial or ventricular septal defects); persistence of the fetal opening between the two major arteries (aorta, pulmonary artery) emerging from the heart (patent ductus arteriosus), and/or a heart defect in which the aortic and pulmonary arteries are in one another’s normal positions. Infants with NLS may be stillborn or develop life-threatening complications shortly after birth. [0008] NLS is transmitted as an autosomal recessive trait. Thus, the risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children risk being carriers of the disease, but generally will not show symptoms of the disorder. Twenty-five percent of their children may receive both normal genes, one from each parent, and will be genetically normal (for that particular trait). [0009] Codon optimization is often used a way to try and maximize the expression of recombinant proteins in various heterologous host organisms, for example, maximize expression of codon-optimized human proteins in yeast cells. SUMMARY [0010] When metabolic diseases are diagnosed early, dietary supplementation or restriction can often reduce or even eliminate disease symptoms. [0011] By determining which alleles of the serine or arginine biosynthetic genes are neutral or pathogenic, the assays described herein would facilitate a gene-sequencing based diagnostic that can be used earlier (including on the developing fetus or the asymptomatic parents). This can be used to determine the genetic outcome of a fetus, or the information may be used to determine the genetic outcome for future progeny of two subjects. The alleles may also be used to develop a personalized therapeutic therapy or to guide intervention to ameliorate symptoms of disease, e.g. amino acid supplementation or dietary restriction that may reduce or prevent morbidity and/or mortality associated with the disease. For example, prenatal diagnosis followed by serine supplementation to the mother starting early in pregnancy and to the patient from birth onward may prevent or ameliorate the onset of symptoms. [0012] In some embodiments, a method of screening a subject for a disease comprises obtaining genomic DNA from the subject, identifying a gene of interest from the genomic DNA, inserting the gene into a construct, wherein the construct is a linear DNA, providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell, introducing the construct into the test cell, evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease, wherein the gene of interest is a metabolic gene or a gene from Table 2. [0013] In some embodiments of the method of screening a subject for a disease, the subject is a fetus, neonate, juvenile or adult. In some embodiments of the method of screening a subject for a disease, the cell and the control cell are yeast cells. In some embodiments of the method of screening a subject for a disease, the amino acid is arginine. In some embodiments of the method of screening a subject for a disease, the subject is pregnant. In some embodiments of the method of screening a subject for a disease, the gene encodes OTC, ASS1, or ASL. In some embodiments of the method of screening a subject for a disease, cell growth is measured by optical density of a liquid culture, a number of pixels of a colony of cells growing on solid media. In some embodiments of the method of screening a subject for a disease, the evaluating step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. In some embodiments of the method of screening a subject for a disease, cell growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell has an optical density that is at least 90% of the growth value of the control cell. In some embodiments of the method of screening a subject for a disease, cell growth of the test cell is slow as compared to the control cell, wherein the cell has an optical density that is 79% or less than the optical density of the control cell. In some embodiments of the method of screening a subject for a disease, the gene of interest is further analyzed for a single-nucleotide polymorphism. In some embodiments of the method of screening a subject for a disease, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. In some embodiments of the method of screening a subject for a disease, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a significant growth difference between the test cell and control cell. In some embodiments of the method of screening a subject for a disease, the significant growth difference indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments of the method of screening a subject for a disease, the disease is NLS, Urea Cycle Disorders or retinal neuropathy. [0014] In some embodiments, a method of determining amino acid deficiency in a subject comprises isolating genomic DNA from a subject, detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway, inserting the gene into a construct, introducing the construct into a test cell, growing up the cell in a media absent of an amino acid; and analyzing growth of the test cell in a culture, wherein the growth of the test cell is compared to a control cell, wherein the control cell is not deficient in amino acid synthesis wherein the test cell growth is compared to the control cell, wherein cell growth of the test cell is comparable to that of the control cell indicates that the gene encodes a functional enzyme and wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene encodes a non-functional protein or protein with decreased function and indicates The method of claim 1, wherein the subject is a fetus, neonate, juvenile or adult, wherein the gene is a metabolic gene or a gene from Table 2. [0015] In some embodiments of the method of determining amino acid deficiency in a subject, the cell and the control cell are yeast cells. In some embodiments of the method of determining amino acid deficiency in a subject, the amino acid is arginine. In some embodiments of the method of determining amino acid deficiency in a subject, the subject is pregnant. In some embodiments of the method of determining amino acid deficiency in a subject, the gene encodes OTC, ASS1, or ASL. In some embodiments of the method of determining amino acid deficiency in a subject, cell growth is measured by optical density of a liquid culture, a number of pixels of a colony of cells growing on solid media. In some embodiments of the method of determining amino acid deficiency in a subject, the analyzing step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. In some embodiments of the method of determining amino acid deficiency in a subject, cell growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell has an optical density that is at least 90% of the growth value of the control cell. In some embodiments of the method of determining amino acid deficiency in a subject, cell growth of the test cell is slow as compared to the control cell, wherein the cell has an optical density that is 79% or less than the optical density of the control cell. In some embodiments of the method of determining amino acid deficiency in a subject, the gene of interest is further analyzed for a single-nucleotide polymorphism. In some embodiments of the method of determining amino acid deficiency in a subject, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. In some embodiments of the method of determining amino acid deficiency in a subject, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a significant growth difference between the test cell and control cell. In some embodiments of the method of determining amino acid deficiency in a subject, the significant growth difference indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments of the method of determining amino acid deficiency in a subject, the disease is NLS, Urea Cycle Disorders, retinal neuropathy, or an amino acid deficiency in the subject. In some embodiments of the method of determining amino acid deficiency in a subject, the analyzing step further comprises identifying at least one mutation in the gene. [0016] In some embodiments, a method of determining a carrier of an amino acid deficiency disorder comprises isolating genomic DNA from a subject, detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway, wherein the subject has two different alleles of the gene, inserting the gene into a construct, wherein the construct is a linear DNA, introducing the construct into a test cell, growing up the test cell in a media absent of an amino acid, and evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein test cell growth is compared to a control cell that has the homologous gene, wherein test cell growth of the cell is comparable to that of the control cell indicates that the gene of interest encodes a functional protein and wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates that the subject is a carrier of an amino acid deficiency disorder, wherein the gene is a metabolic gene or a gene from Table 2. [0017] In some embodiments of the method of determining a carrier of an amino acid deficiency disorder, the amino acid deficiency disorder is NLS. [0018] In some embodiments, a method of treating a subject with an amino acid deficiency comprises determining a subject or carrier of an amino acid deficiency disorder, wherein the determining comprises detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway, inserting the gene into a construct, wherein the construct is a linear DNA, introducing the construct into a test cell, growing up the test cell in a media absent of an amino acid, and evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein test cell growth is compared to a control cell that has the homologous gene, wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene of interest encodes a non- functional protein or protein with decreased function and indicates that the subject is a carrier of an amino acid deficiency disorder, providing an adequate amount of an amino acid supplement to the subject, wherein the gene is a metabolic gene or a gene from Table 2. [0019] In some embodiments of the method of treating a subject with an amino acid deficiency, the amino acid supplement is arginine. In some embodiments of the method of treating a subject with an amino acid deficiency, the enzyme is wherein the gene encodes OTC, ASS1, or ASL. In some embodiments of the method of treating a subject with an amino acid deficiency, the subject is a fetus and wherein the mother of the fetus is provided an adequate amount of amino acid supplement. In some embodiments of the method of treating a subject with an amino acid deficiency, the evaluating further comprises comparing growth of the test cell to a second control cell, wherein the second control cell is deficient in arginine biosynthesis. The method of any one of the embodiments provided herein, wherein the amino acid deficiency disorder is NLS or a Urea Cycle Disorder. [0020] In some embodiments, a method of prenatal prediction of an amino acid deficiency comprises obtaining genomic DNA from a female and male subject, identifying a same gene of interest from the genomic DNA of the female and male subject, wherein the subjects are homozygous or heterozygous for the gene, inserting a first gene variant of interest from the female into a first construct, wherein the first construct is a linear DNA, inserting a second gene variant of interest from the male into a second construct, wherein the second construct is a linear DNA, providing a first cell, wherein the first cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell, providing a second cell, wherein the second cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell, introducing the first construct into the first cell, wherein the first construct is a linear DNA, introducing the second construct into the second cell, wherein the second construct is a linear DNA, and evaluating the first and second cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the first and second cell are compared to a control cell that has the homologous gene, wherein cell growth of the first and/or second cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the first and second cell is slow as compared to the control cell indicates that the first and second gene of interest encodes a non-functional protein or protein with decreased function and indicates that the male and/or female is a carrier of a disease for an amino acid deficiency, wherein the same gene of interest is a metabolic gene or a gene from Table 2. [0021] In some embodiments, the method of prenatal prediction of an amino acid deficiency further comprises making a diploid strain of a third cell, wherein the third cell comprises the first and second gene of interest and evaluating the third cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the third cell are compared to a control cell that has the homologous gene, wherein cell growth of the third cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the third cell is slow as compared to the control cell indicates that the first and second gene of interest together indicates a predicted fetus with an amino acid deficiency. In some embodiments, a method of prenatal prediction of an amino acid deficiency data from the first, second and third cell is stored in a look-up table, wherein the look-up table is generated for disease prediction. In some embodiments, a method of prenatal prediction of an amino acid deficiency the disease for an amino acid deficiency is NLS. [0022] In some embodiments, a method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation comprises: a) obtaining genomic DNA from a female and male subject; b) identifying a same gene of interest from the genomic DNA of the female and male subject, wherein the subjects are homozygous or heterozygous for the gene; c) inserting a first gene of interest from the female into a first construct; d) inserting a second gene of interest from the male into a second construct; e) providing a first cell, wherein the first cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell; f) providing a second cell, wherein the second cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell; g) making a diploid strain of a third cell, wherein the third cell comprises the first and second gene of interest; h) introducing the first construct into the first cell, wherein the first construct is a linear DNA; i) introducing the second construct into the second cell, wherein the second construct is a linear DNA; and j) evaluating the first, second, and third cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the first and second cell are compared to a control cell that has the homologous gene, wherein cell growth of the first, second and third cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the first, second and third cell is slow as compared to the control cell indicates that the first and second gene of interest encodes a non-functional protein or protein with decreased function and predicts an amino acid deficiency for progeny, wherein the same gene of interest is a metabolic gene or a gene from Table 2. [0023] In some embodiments of the method of prenatal prediction, the first gene of interest or the second gene of interest comprises the gene mutation. In some embodiments of the method of prenatal prediction, the gene of interest encodes OTC, ASS1, or ASL. In some embodiments of the method of prenatal prediction, the gene of interest encodes OTC, ASS1, or ASL with at least one of the amino mutations otc-R141Q, ass1-R127W, asl-Q286R . In some embodiments of the method of prenatal prediction, data from the first, second and third cell is stored in a look-up table, wherein the look-up table is generated for disease prediction. In some embodiments of the method of prenatal prediction, the amino acid deficiency is caused by NLS. [0024] In some embodiments, a kit for determining amino acid deficiency comprises a look-up table, wherein the look up table indicates genes or combinations of genes that may be indicative of an amino acid deficiency or disease, one or more nucleic acid probes for detecting one or more mutation in OTC, ASS1, or ASL, wherein the one or more mutation includes at least: otc-R141Q, ass1-R127W, asl-Q286R. [0025] In some embodiments, a method of determining if a subject is suffering from an amino acid deficiency, the method comprises providing a look-up table, wherein the look-up table comprises genes or a combination of genes that are indicative of a disease, isolating genes of interest from a subject, determining if the genes include one of more mutations in the look-up table, and determining a probability of disease in the subject, wherein the genes or a combination of genes are metabolic genes or genes from Table 2. [0026] In some embodiments, the look up table comprises combination of genes that include genes of OTC, ASS1, or ASL, wherein the OTC, ASS1, or ASL genes encode OTC, ASS1, or ASL comprising mutations otc-R141Q, ass1-R127W, asl-Q286R. [0027] In some embodiments, the look up table comprises a list of mutations that have been determined by the method provided herein, said method further comprising administering an amino acid supplement to the subject to treat the amino acid deficiency if the subject has more than a 50% probability of having the amino acid deficiency. [0028] In some embodiments, the at least one mutation is otc-R141Q, ass1- R127W, asl-Q286R, and wherein the subject is an unborn child of a mother, wherein the mother is tested for the presence of the at least one mutation. [0029] In some embodiments, a method of identifying a point mutation as a cause or marker of an amino acid deficiency comprises obtaining genomic DNA from a subject having the amino acid deficiency, identifying a point mutation in the genomic DNA in at least one of OTC, ASS1, or ASL, providing a test yeast cell, wherein a homologous gene of at least one of OTC, ASS1, or ASL has been knocked out of the test yeast cell, introducing the gene with the point mutation into the test yeast cell, and evaluating the test yeast cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test yeast cell growth is compared to a control cell that has the homologous gene, wherein when test yeast cell growth is comparable to that of the control cell it indicates that the point mutation still allows for a functional protein, and wherein when the test yeast cell growth is slow as compared to the control cell it indicates that the point mutation results in a non-functional protein or protein with decreased function, thereby identifying the point mutation as a cause or marker of an amino acid deficiency. In some embodiments, a method of preparing a personalized yeast model for determining a subject at risk of a disease comprises: a) obtaining genomic DNA from the subject; b) identifying a gene of interest in at least two alleles from the genomic DNA; c) inserting the gene into a construct, wherein the construct is a linear DNA; d) providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell; e) introducing the construct into the test cell; f) evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease; g) generating data for a look-up table; and h) generating one or more personalized disease amelioration recommendations for the subject; and presenting the one or more personalized disease prevention recommendations for the subject in the personalized disease prevention plan for the subject for disease management, wherein the gene of interest is a metabolic gene or a gene from Table 2. [0030] In some embodiments of the method of preparing a personalized yeast model, the method further comprising: a) obtaining a second genomic DNA from a second subject, wherein the second subject has a second set of two alleles that are related to the two alleles of the subject, and second set of two alleles have a second gene of interest, wherein the second gene of interest is placed in a second construct b) introducing the second construct into a second test cell, evaluating the second test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when second test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function. [0031] In some embodiments, the method of preparing a personalized yeast model further comprising obtaining a second genomic DNA from a second subject and identifying a second gene(s) of interest in at least two alleles from the genomic DNA, inserting at least one of the second gene(s) into a second construct, introducing the second construct into a second test cell, and mating the second cell with the first cell to produce a progeny cell. [0032] In some embodiments, the method of preparing a personalized yeast model further comprising evaluating the progeny cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when progeny cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the progeny cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. [0033] In some embodiments of the method of screening a subject for a disease, the evaluating further comprises quantifying cell growth by photographing yeast growing on solid agar plates and performing image analysis using a custom software. [0034] In embodiments of any of the foregoing methods or kits, the codons in the gene are reverse harmonized. [0035] In embodiments of any of the foregoing methods or kits, the codons in the gene are reverse harmonized for expression in yeast [0036] In embodiments of any of the foregoing methods or kits, the gene is codon optimized for expression in yeast based on a frequency of usage of a codon in yeast. [0037] In embodiments of any of the foregoing methods or kits, the disease is a urea cycle disorder. [0038] In embodiments of any of the foregoing methods or kits, the disease is a urea cycle disorder caused by a mutation in one or more of OCT, ASS1, or ASL. [0039] In some embodiments, a method of codon optimization by reverse harmonization comprises obtaining a sequence of a first gene/cDNA to be optimized from a first organism, obtaining a sequence of a second gene/cDNA from a second organism, wherein the second gene/cDNA is an ortholog of the first gene/cDNA, and the first (“foreign”) gene/cDNA is to be optimized for expression in the second (“host”) organism; performing a first alignment of the first and second gene/cDNA sequences; obtaining a protein sequence encoded by the first gene/cDNA; obtaining a protein sequence encoded by the second gene/cDNA; performing a second alignment of the protein sequences encoded by the first and second gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in the first and second gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in the first gene/cDNA with the codon in the second gene/cDNA, if the codons in the first and second gene/cDNA encode the same amino acid at mutually corresponding positions in the second alignment are different between the first and second gene/cDNA, thereby obtaining a version of the first gene/cDNA from the first organism that is codon optimized for expression in the second organism. [0040] In some embodiments, the method of codon optimization by reverse harmonization further comprises identifying positions in the first alignment where codons differ between the first and the second genes/DNA; and replacing codons in the first gene/cDNA lacking corresponding codons in the second gene/cDNA by selecting codons from the second organism that encode the same amino acid. In some embodiments of the method of codon optimization by reverse harmonization, selecting codons from the second organism is based on a frequency of usage of a codon encoding a particular amino acid in the second organism. In some embodiments of the method of codon optimization by reverse harmonization, a protein encoded by the codon optimized first gene/cDNA is expressed more efficiently and/or at a higher level in the second organism as compared to a codon non- optimized first gene/cDNA. In some embodiments of the method of codon optimization by reverse harmonization, the protein encoded by the codon optimized first gene/cDNA is a protein expressed more efficiently and at a higher level in the second organism for an application selected from the group consisting of beer production, wine production, baking, bioremediation, oil remediation, industrial ethanol production, production of nutritional supplements, production of probiotics, protein expression for biochemical and/or biophysical research, and protein therapy. [0041] In some embodiments of the method of codon optimization by reverse harmonization, the protein encoded by the codon optimized first gene/cDNA is a protein expressed more efficiently and at a higher level in the second organism for an application selected from the group consisting of biofuel production, antibody screening, and/or antibody production. BRIEF DESCRIPTION OF THE DRAWINGS [0042] Figure 1 shows schematic of the universal cell type for assaying protein function of a protein that is implicated in, for example, the serine biosynthesis pathway. As shown, yeast and humans have homologs for proteins implicated in the serine biosynthesis pathway. These enzymes are conserved between yeast and humans. [0043] Figure 2 shows an exemplary quantitative yeast assay for PSAT1 function in which yeast cells are grown in media that lacks serine. As shown, is a construct of a nucleic acid comprising a transcriptional regulatory sequence with a 5’ and 3’ untranslated regions (UTR) flanking a human coding sequence. In the embodiments herein, the human coding sequence is a homolog of a yeast protein sequence that is implicated in a metabolic pathway. As shown in the bar graph below is the measurement of the growth of yeast cells expressing a control gene (yeast gene SER1), ser1 deletion, PSAT1 gene, PSAT1 variant 1 and PSAT1 variant 2, where variants 1 and 2 are known disease alleles. [0044] Figure 3 shows a quantitative yeast assay for PSAT1 function in the absence of serine. Growth in the absence of exogenously supplied serine, for wildtype strain (“yeast gene”), a ser1 deletion (“no gene”) or strains with human PSAT1 coding sequence or two human disease gene variants (A99V and S179L, respectively). A t-test between “yeast gene” and “human gene” growth was not significant (N.S.) The growth conferred by variants 1 and 2 (disease alleles were significantly below that of the human gene (t-test p-values < 0.0001, ***). There was no significant difference between a gene deletion and variant 2, suggesting that variant 2 is equivalent to a complete loss of function. [0045] Figure 4 shows a comparison between a computational analysis of enzyme mutants and a quantitative yeast assay of the enzyme mutants. As shown, computational methods do a poor job of predicting functional consequences. In the left panel is a bar graph that shows the measurement of the growth of yeast cells expressing several PSAT mutations: 1) 1) K110Q, 2) V149M, 3) T156M, 4) R222*, 5) N236H 6) V250A. As shown in the right panel is a table with the computational predictions of the functions of the PSAT proteins: 1) K110Q, 2) V149M, 3) T156M, 4) R222*, 5) N236H 6) V250A. [0046] Figure 5 shows an example literature search for several PSAT1 alleles that may be associated with disease. Patients are labeled with the last name of the first author on the publication describing them. Labels refer to the patient identifiers used in those publications, e.g. “patient 1” or “DDD4K.03775”. [0047] Figure 6 shows a qualitative assay of testing disease alleles individually. Growth in the absence of serine for strains harboring human PSAT1 coding sequence (PSAT1), three known human disease gene variants (A99V, D100A, S179L), or suspected pathogenic variants that were classified as (G78A and R213C). S179L and G78A have growth comparable to null alleles. [0048] Figure 7 shows an example of an assay for personalized yeast models of affected individuals and carrier parents. Growth in the absence of serine of diploid strains harboring human PSAT1 (PSAT1/ PSAT1), the alleles of the carrier parents (PSAT1/ A99V or PSAT1/ S179L), or the compound heterozygosity of an affected patient from the literature (AV99V/S179L). Constructing and assaying “trios” for all 9 patient genotypes can be performed. [0049] Figure 8 shows an example of predicting the neural threshold, and pathogenic threshold for the PSAT1 genes. Also calculated is the region between neutral and pathogenic in which pathogenicity cannot be accurately assessed at this time (labeled as variant of uncertain significance (VUS)). [0050] Figure 9 shows growth values of several haploids in the absence of serine for haploid strains containing the PSAT1 variants listed above each bar. From left to right is PSAT (control), A15V, A99V, c.delG107, D100A, D145Mfs*49, G78A, R213C, R342Dfs*6, S179L, S43R and S43R. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (control). These are all alleles that have been associated with disease in the literature. A15V, A99V, c.delG107, D100A, D145Mfs*49 and S179L are considered in the literature as being pathogenic, G78A, R213C and S43R are annotated as variants of uncertain significance (VUS). [0051] Figure 10 shows a “personalized yeast model” for affected patients (4) and their carrier parents (2 and 3) (PSAT x D100A and c.delG107 x D100A), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (Hart et al) . The file names list the patient(s), e.g. 01-Hart_1_2 corresponds to Hart 1 and Hart 2 (both have the same parents and genotype). The strains are diploids. As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (carrier, 2 and 3). Note that there are some cases where both parents had the same carrier genotype. In these cases, there is only one bar. As shown in Figure 10, the progeny has two PSAT alleles (delG107 x D100A) that leads to a protein with decreased function. [0052] Figure 11 shows a “personalized yeast model” for affected patient (3) and their carrier parent(s) (2), with the wildtype (1) for reference. The carrier parents are both Arg342Aspfsכ6 X PSAT1. Note that these are the same patients that are described in Figure 5 (Acuna-Hidalgo et al). The strains are diploids. As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (2). Note that there are some cases where both parents had the same carrier genotype. In these cases, there is only one bar. As shown in Figure 11, the progeny (3) has two PSAT alleles (Arg342Aspfsכ6 x Arg342Aspfsכ6) that leads to a protein with loss of function. [0053] Figure 12 shows a “personalized yeast model” for affected patient (3) and their carrier parent(s) (2), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (Acuna-Hidalgo et al). The strains are diploids. As with the previous figures, the PSAT1 variants are listed above each bar. Both parents are A99V x PSAT1. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (2). Note that there are some cases where both parents had the same carrier genotype, as in this particular case. In these cases, there is only one orange bar. As shown in Figure 12, the progeny (3) has two PSAT1 alleles (A99V x A99V) that leads to a protein with decreased function. [0054] Figure 13 shows a “personalized yeast model” for affected patient (3) and their carrier parent(s) (2), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (Acuna-Hidalgo et al). The strains are diploids. The parents are both PSAT X S179L. As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (2). Note that there are some cases where both parents had the same carrier genotype, as in this particular case. In these cases, there is only one bar. As shown in Figure 13, the progeny (3) has two PSAT1 alleles (S179L x S179L) that leads to a protein with complete loss of function. [0055] Figure 14 shows a “personalized yeast model” for affected patients (4) and their carrier parents (2 and 3), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (Acuna-Hidalgo et al). The strains are diploids. The parents are PSAT1 x S179L and A99V x PSAT1. As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (carrier, 2 and 3). Note that there are some cases where both parents had the same carrier genotype. In these cases, there is only one bar. As shown in Figure 14, the progeny (4) has two PSAT alleles (A99V x S179L) that leads to a protein with decreased function. [0056] Figure 15 shows a “personalized yeast model” for affected patient (3) and their carrier parent(s) (2), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (Brassier et al). The strains are diploids. Both parents are S43R x PSAT1. As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (2). Note that there are some cases where both parents had the same carrier genotype, as in this particular case. In these cases, there is only one bar. As shown in Figure 15, the progeny (3) has two PSAT1 alleles (S43R x S43R) that leads to a protein that is comparatively as functional as the parent. [0057] Figure 16 shows a “personalized yeast model” for affected patient (3) and their carrier parent(s) (2), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (Monies et al). The strains are diploids. Both parents are G78A x PSAT1. As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (2). Note that there are some cases where both parents had the same carrier genotype, as in this particular case. In these cases, there is only one orange bar. As shown in Figure 16, the progeny (3) has two PSAT1 alleles (G78A x G78A) that leads to a protein has a complete loss of function as compared to the parent and the wild type. [0058] Figure 17 shows a “personalized yeast model” for affected patient (3) and their carrier parent(s) (2), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (McRae et al). The strains are diploids. Both parents are R213C x PSAT1. As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (2). Note that there are some cases where both parents had the same carrier genotype, as in this particular case. In these cases, there is only one orange bar. As shown in Figure 17, the progeny (3) has two PSAT1 alleles (R213C x R213C) that leads to a protein has decreased function as compared to the parent and the wild type. [0059] Figure 18 shows a “personalized yeast model” for affected patients (4) and their carrier parents (2 and 3), with the wildtype (1) for reference. Note that these are the same patients that are described in Figure 5 (Glinton et al). The strains are diploids. The parents are PSAT1 x A15V and D145Mfs*49 x PSAT100). As with the previous figures, the PSAT1 variants are listed above each bar. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (carrier, 2 and 3). Note that there are some cases where both parents had the same carrier genotype. In these cases, there is only one bar. As shown in Figure 18, the progeny (4) has two PSAT alleles (D145Mfs*49 x A15V) that lead to a protein with decreased function as compared to the wild type. However, the progeny does have similar protein characteristics with one of the parents (Bar 3). [0060] Figure 19 shows yeast models of OTC, ASS1, and ASL. Growth is expressed relative to strain harboring the yeast orthologs (bars with lighter shading). The graphs data from an exemplary quantitative yeast assay for OTC, ASS1, and ASL function in which yeast cells are grown in media that lacks arginine. The yeast enzymes in three colinear steps of the arginine biosynthesis pathway are highly conserved with their human orthologs (Table 1). The bar graphs show measurement of the growth of yeast cells expressing the native forms of the three genes (ARG3, ARG1, and ARG4) of the arginine biosynthesis pathway, yeast cells lacking the native the arginine biosynthesis pathway genes, ARG3, ARG1, and ARG4, yeast cells expressing human orthologs of ARG3, ARG1, and ARG4, namely, OCT, ASS1, and ASL, respectively, and yeast cells expressing variants of OCT, ASS1, and ASL, namesly, otc-R141Q, ass1-R127W, asl-Q286R. growth was measured in media lacking arginine (Example 4). [0061] Figure 20 shows an embodiment of a codon harmonization method (Example 5). [0062] Figure 21 shows an embodiment of an alignment of nucleotide sequences of ARG3 and OTC. The figure not only shows the aligned sequences of the natural yeast (ARG3; SEQ ID NO: 4) and human (OTC-original; SEQ ID NO: 5) genes, but also the sequence that is generated after protein harmonization method and associated software (OTC-recoded; SEQ ID NO: 6). [0063] Figure 22 shows an embodiment of an alignment of protein sequences of ARG1 (SEQ ID NO: 8) and OTC (SEQ ID NO: 7). [0064] Figure 23 shows an embodiment of an alignment of nucleotide sequences of ZWF1 and G6PD. The figure not only shows the aligned sequences of the natural yeast (ZWF1; SEQ ID NO: 9) and human (G6PD-original; SEQ ID NO: 10) genes, but also the sequence that is generated after protein harmonization method and associated software (G6PD-recoded; SEQ ID NO: 11). [0065] Figure 24 shows an embodiment of an alignment of protein sequences of ZWF1 (SEQ ID NO: 13) and G6PD1 (SEQ ID NO: 12). [0066] Figure 25 shows an embodiment of an alignment of nucleotide sequences of ARG1 and ASS1. The figure not only shows the aligned sequences of the natural yeast (ARG1; SEQ ID NO: 14) and human (ASS1-original; SEQ ID NO: 15) genes, but also the sequence that is generated after protein harmonization method and associated software (ASS1-recoded; SEQ ID NO: 16). [0067] Figure 26 shows an embodiment of an alignment of protein sequences of ARG1 (SEQ ID NO: 18) and ASS1 (SEQ ID NO: 17). [0068] Figure 27 shows an embodiment of an alignment of nucleotide sequences of ARG4 and ASL. The figure not only shows the aligned sequences of the natural yeast (ARG4; SEQ ID NO: 19) and human (ASL-original; SEQ ID NO: 20) genes, but also the sequence that is generated after protein harmonization method and associated software (ASL-recoded; SEQ ID NO: 24). [0069] Figure 28 shows an embodiment of an alignment of protein sequences of ARG4 (SEQ ID NO: 23) and ASL (SEQ ID NO: 22). [0070] Figure 29 shows an embodiment of a codon optimized ASL protein coding nucleotide sequence (SEQ ID NO: 24) generated after the harmonization method and associated software herein. [0071] Figure 30 shows an embodiment a codon optimized ASL protein coding nucleotide sequence (SEQ ID NO: 21) generated after the harmonization method and associated software herein. Definitions [0072] 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 the invention pertains. [0073] As used herein, “a” or “an” may mean one or more than one. [0074] “About” as used herein when referring to a measurable value is meant to encompass variations of ±20% or ±10%, more preferably ±5%, even more preferably ±l%, and still more preferably ±0.1 % from the specified value. [0075] “Polynucleotide,” as described herein refers to “nucleic acid” or “nucleic acid molecule,” such as deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), oligonucleotides, fragments generated by the polymerase chain reaction (PCR), and fragments generated by any of ligation, scission, endonuclease action, and exonuclease action. Nucleic acid molecules can be composed of monomers that are naturally-occurring nucleotides (such as DNA and RNA), or analogs of naturally-occurring nucleotides (e.g, enantiomeric forms of naturally-occurring nucleotides), or a combination of both. Modified nucleotides can have alterations in sugar moieties and/or in pyrimidine or purine base moieties. Sugar modifications include, for example, replacement of one or more hydroxyl groups with halogens, alkyl groups, amines, and azido groups, or sugars can be functionalized as ethers or esters. Moreover, the entire sugar moiety can be replaced with sterically and electronically similar structures, such as aza-sugars and carbocyclic sugar analogs. Examples of modifications in a base moiety include alkylated purines and pyrimidines, acylated purines or pyrimidines, or other well-known heterocyclic substitutes. Nucleic acid monomers can be linked by phosphodiester bonds or analogs of such linkages. Analogs of phosphodiester linkages include phosphorothioate, phosphorodithioate, phosphoroselenoate, phosphorodiselenoate, phosphoroanilothioate, phosphoranilidate, phosphoramidate, and the like. The term “nucleic acid molecule” also includes so-called “peptide nucleic acids,” which comprise naturally-occurring or modified nucleic acid bases attached to a polyamide backbone. Nucleic acids can be either single stranded or double stranded. In some alternatives, a nucleic acid sequence encoding a fusion protein is provided. In some alternatives, the nucleic acid is RNA or DNA. [0076] “Expression construct” or “construct” is a nucleic acid used to introduce heterologous nucleic acids into a cell that has regulatory elements to provide expression of the heterologous nucleic acids in the cell. The constructs described herein include but are not limited to plasmid, minicircles, yeast, and viral genomes. [0077] A single copy of the construct is inserted stably into the yeast genome (at either the same position as the yeast gene, which has been deleted or at a neutral position in the genome, e.g. the HO locus). In the embodiments herein, the construct is a “linear DNA molecule (double or single stranded) that can be integrated into the yeast nuclear or mitochondrial genome by homologous recombination. These constructs may be synthesized in vitro by a commercial gene synthesis company (e.g. Twist Biosciences or IDT). As such the nucleic acid sequence could be the human sequence or a yeast optimized version that encodes the same protein sequence. [0078] “Coding for" or “encoding” have their plain and ordinary meaning when read in light of the specification, and may include but is not limited to, for example, the property of specific sequences of nucleotides in a polynucleotide, such as a gene, a cDNA, or an mRNA, to serve as templates for synthesis of other macromolecules such as a defined sequence of amino acids. Thus, a gene codes for a protein if transcription and translation of mRNA corresponding to that gene produces the protein in a cell or other biological system. [0079] Serine Deficiency Syndrome/Neu-Laxova Syndrome (NLS) refers to a disease of individuals with homozygous or compound heterozygous loss of function mutations in any of three metabolic genes responsible for the biosynthesis of serine cause a severe neurodevelopmental syndrome that presents with congenital microcephaly, intractable seizures, and severe psychomotor retardation (See Figure 1). As described herein, Serine Deficiency Syndrome and Neu-Laxova Syndrome (NLS) are used interchangeably. Neu– Laxova syndrome (NLS) is a very severe disorder, leading to stillbirth, neonatal death, or severe developmental delay. However, if diagnosed early, dietary supplementation can reduce or even eliminate disease symptoms. In one case study, prenatal diagnosis followed by serine supplementation (to the mother) starting early in pregnancy and to the patient from birth onward completely prevented the onset of symptoms. Serine sources can be taken at a 600/mg/kg/day for those suffering from a serine deficiency in 4 to 6 doses in a day. [0080] NLS is a heterogeneous metabolic disorder caused by homozygous or compound heterozygous mutations in the PHGDH, PSAT1 and PSPH genes, which are involved in the serine biosynthesis pathway and are essential for cell proliferation. Mutations in all three genes had been previously identified as the cause of serine-deficiency syndromes. Milder forms of the disease also exist. NLS is found in 1 in 5000 births. [0081] “Retinal neuropathy” is any damage to the retina of the eyes, which may cause vision impairment. Retinopathy often refers to retinal vascular disease, or damage to the retina caused by abnormal blood flow. Age-related macular degeneration is technically included under the umbrella term retinopathy but is often discussed as a separate entity. Retinopathy, or retinal vascular disease, can be broadly categorized into proliferative and non-proliferative types. In some cases the retinal neuropathy may be caused by a deficiency in an amino acid, such as serine. In some embodiments herein, a subject is at risk at developing retinal neuropathy and is selected to receive an appropriate amount of serine for treatment. In some case, other amino acid deficiencies may be involved in other forms of neuropathy. [0082] Additionally, milder forms of serine deficiencies have been reported. These milder forms of serine deficiencies have been predicted to be associated with adult onset diseases. Scerri et al. describes a serine deficiency, macular telangiectasia type 2 (MacTel), which manifests at age 40-60, in which subjects afflicted by MacTel suffer from abnormal right-angled juxtafoveolar capillaries and parafoveal telangiectasias. For MacTel, mutations in several alleles have been implicated in the disease which leads to problems in the glycine and serine metabolic pathway. [0083] The subject as described in the embodiments herein may be a fetus, neonate, juvenile or adult. “Fetus” has its plain and ordinary meaning when read in light of the specification, and may include but is not limited to, for example, a prenatal human between its embryonic state and its birth. “Neonate” refers to a newborn child. “Juvenile” refers to a person under the established age of 18 years. “Adult” refers to a person any age over 18. [0084] “Look-up table” has its plain and ordinary meaning when read in light of the specification, and may include but is not limited to, for example, a table prepared with a is a combination of genes that may predict a fatal outcome. In the embodiments herein, the look-up table may predict a retinal disease dependent on serine, NLS, or metabolic disease such as an amino acid deficiency. The data on the look-up table also provide different predicted thresholds for determining the functions of the protein as there are different thresholds for combinations of alleles for different diseases. [0085] As used herein, a “foreign host” refers to a heterologous host organism. For example, in the context of protein expression, a foreign host (also referred to herein as a heterologous host organism) is a host organism in which a protein that the host organism does not normally make is expressed, for example, yeast or bacteria would be a foreign host for a human protein. [0086] “Cell growth” also referred to as the “growth value”, is measured by optical density of a liquid culture. In some embodiments, cell growth, also the “growth value”, is measured by the area of a “patch” or “spot” of cells growing on solid media, the number of pixels of a “patch” or “spot” of cells growing on solid media, the intensity of the pixels in a “patch” or “spot” of cells growing on solid media, the size of the a “patch” or “spot” of cells growing on solid media, the change in any of these parameters over time, or a combination of any of the aforementioned parameters. DETAILED DESCRIPTION [0087] Without being limited by any particular theory, most heterologous expression strategies are focused on the goal of expressing as much of the protein as possible. Thus, these strategies often use really strong promoters to express high levels of mRNA and codon optimization that replaces rare codons with more frequently used ones. In some embodiments, an innovative aspect of the methods of codon optimization herein is to not try and make the most possible as fast as possible. Without being limited by any particular theory, it is believed that the host (e.g., yeast) regulatory sequences (transcriptional promoters, transcriptional terminators, RNA stability elements, and rates of translation, i.e., codon usage) have evolved to make the optimal amount of a given protein/enzyme under a given environmental condition. Furthermore, without being limited by any particular theory, it is believed that if the optimal amount of a given protein/enzyme that the host needs is made, the assay for the function of that protein/enzyme (e.g., yeast growth) will work better. [0088] Some embodiments herein relate to methods for codon harmonization in which the codons of a heterologous protein coding sequence are altered to more closely match the usage frequency of the codons in orthologous positions of the host organism’s orthologous gene, even if the amino acids encoded at those position differ between the two orthologs. [0089] In humans, serine is a nutritionally non-essential amino acid. The main source of essential amino acids is from the diet, however non-essential amino acids are normally synthesized by humans and other mammals from common intermediates. As shown in Figure 1, serine is biosynthesized from a glycolytic intermediate, 3-phosphoglycerate (3- PG), in a three-step process involving the enzymes: 3-phosphoglycerate dihydrogenase (3- PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). [0090] Serine can also be derived in a reversible reaction from glycine; through degradation of protein and phospholipids; and through dietary intake. For this reason, NLS is usually treated by dietary supplementation with both serine and glycine. The primary pathway maintaining adequate serine concentrations is likely to depend on tissue type and stage of development as described by de Koning et al., 2003 (de Koning et al., 2003). [0091] Serine plays a functional role in cell growth and development. For example, the conversion of serine to glycine by serine hydroxymethyltransferase results in the formation of the one-carbon units necessary for the synthesis of the purine bases, adenine and guanine. These bases may be linked to the phosphate ester of pentose sugars and are essential components of DNA and RNA, with end-products of energy producing metabolic pathways, ATP and GTP. Additionally, serine conversion to glycine through the enzymatic pathway provides one-carbon units necessary for production of the pyrimidine nucleotide, deoxythymidine monophosphate, which is also an essential component of DNA. [0092] Serine also plays a role as a precursor for the neurotransmitters glycine and D-serine, and indirectly through L-cysteine, for the neurotransmitter taurine. Glycine can be synthesized from serine and is an inhibitory neurotransmitter, which may bind to the glycine receptor on the post-synaptic membrane or together with glutamate as a co-agonist. Essential components that can be made from serine include D-serine, which is an agonist of the NMDA receptor and cysteine, which can be formed from serine through a trans- sulfuration pathway. This leads to precursors for proteins, glutathione, taurine, coenzyme A and inorganic sulfate. Taurine functions as an inhibitory neurotransmitter and is likely to play a role in pre- and post-natal development of the central nervous system. Thus, serine is much needed in multiple pathways such as cell growth pathways. [0093] Serine deficiency is a rare, inherited, metabolic disorder of serine biosynthesis. The majority of the cases reported in the literature so far show a decrease in 3- phosphoglycerate dehydrogenase (3-PGDH) activity resulting in low fasting serum and CSF serine levels. Children with serine deficiency present with congenital microcephaly may develop severe psychomotor retardation and intractable seizures. [0094] Several mutations have been identified in the gene encoding human 3- PGDH located on chromosome one (1p12 or 1q12). Several examples of mutations are described in Klomp et al, 2000 and Pind et al, 2002. Some mutations result in a substitution of valine for methionine at position 490 (V490M) of the enzyme in most of the cases reported, or a V425M substitution in one reported case (Klomp et al, 2000, Pind et al, 2002). [0095] Nearly all children born with serine deficiency have congenital microcephaly. In addition, hallmark signs of Serine deficiency include severe psychomotor retardation, seizures, spastic quadriplegia and in some patients, nystagmus, megaloblastic anemia, cataract and hypogonadism. [0096] In children born with serine deficiency, a low level of serine in the cerebral spinal fluid (CSF) is the most reliable indicator for both 3-phosphoglycerate dehydrogenase (3-PGDH) and 3-phosphoserine phosphatase (3-PSP) deficiency. In some, but not all cases, CSF glycine levels were below normal. In the fasted state, plasma serine and to a lesser extent, plasma glycine levels are below normal levels. Urine amino acid levels are normal. (de Koning and Klomp. 2004). Individuals with homozygous or compound heterozygous loss of function mutations in any of three metabolic genes responsible for the biosynthesis of serine may cause a severe neurodevelopmental syndrome that presents with congenital microcephaly, intractable seizures, and severe psychomotor retardation. Thus a mutation leading to an enzyme with a loss of function would lead to the limiting step of serine biosynthesis. [0097] The currently accepted diagnostic for serine deficiency is measuring serine levels from the cerebrospinal fluid, which cannot be performed until after birth when many of the symptoms, such as developmental delay, are irreversible. As such, a method is needed to determine the likelihood of developing the disease in a fetus in order to provide treatment prior to the manifestation of the disease. By determining which alleles of the serine biosynthetic genes are neutral or pathogenic, the assays described would facilitate a gene- sequencing based diagnostic that can be used earlier (including on the developing fetus or the asymptomatic parents). [0098] Arginine, a semiessential or conditionally essential amino acid in humans, is one of the most metabolically versatile amino acids and serves as a precursor for the synthesis of urea, nitric oxide, polyamines, proline, glutamate, creatine, and agmatine. Arginine is metabolized through a complex and highly regulated set of pathways that remain incompletely understood at both the whole-body and the cellular levels. Adding to the metabolic complexity is the fact that limited arginine availability can selectively affect the expression of specific genes, most of which are themselves involved in some aspect of arginine metabolism. This overview highlights selected aspects of arginine metabolism, including areas in which our knowledge remains fragmentary and incomplete. Morris Jr., S.M., Arginine: beyond protein, The American Journal of Clinical Nutrition, Volume 83, Issue 2, February 2006, Pages 508S–512S. [0099] Arginine is used for a number of biological processes, including being available to be broken down into chemical intermediates that replenish the Krebs Cycle. In addition to this important anaplerotic role through conversion to glutamate and subsequently alpha-keto-glutarate, arginine is a necessary substrate in humans as an intermediate of the urea cycle. The urea cycle, probably the most well-known metabolic pathway, involves arginine as a carrier of nitrogenous waste. The final step in that pathway is catalyzed by the enzyme arginase (ARG), converting arginine to ornithine and urea; this allows urea to be available for excretion and regenerates ornithine to reenter the cycle (See, Albaugh, V.L, et al., sciencedirect.com/science/article/pii/B9780128096338060829?v ia%3Dihub) [0100] The complete urea cycle is found only in the liver, although individual enzymes are present at lesser levels in other organs and may have additional metabolic roles. Severe liver disease with biosynthetic failure may also result in a deficient urea cycle and hyperammonemia. The first three enzymes in this cycle, N-acetylglutamate synthase (NAGS), carbamoyl phosphate synthase I (CPSI), and ornithine transcarbamylase (OTC) function inside mitochondria, and the latter three, argininosuccinic acid synthase, argininosuccinic acid lyase (ASL), and arginase, act in the cytosol (See, Fenichel, G.M., Metabolic Disorders, Neonatal Neurology (Fourth Edition), 2007). The reactions of the urea cycle are shown in Table 0.1. Table 0.1 [0101] ARG1, arginase; ASL, argininosuccinic acid lyase; ASS, argininosuccinic acid synthase; Co-A, coenzyme A; CP, carbamoyl phosphate; CPS-1, carbamoyl phosphate synthase; NAG, N-acetylglutamate; NAGS, N-acetylglutamate synthase; NO, nitric oxide; NOS, nitric oxide synthase; OTC, ornithine transcarbamylase. Development of an assay for determining deleterious proteins [0102] As provided herein, an assay was developed to determine a deleterious protein that functions in a metabolic pathway. As shown in Figure 1, serine is produce in a three step pathway to generate serine from 3-phosphoglycerate. In humans, this relies on three proteins 3-PGDH, PSAT1 and PSPH which are also conserved homologs in yeast (SER3, SER33, SER1 and SER2). It has been shown that PSAT1 can be knocked out and replaced in yeast with the human homolog. It is anticipated that knockouts of the 3-PGD-H and PSPH can be replaced by their human homologs as well. Moreover, as provided herein, this modified yeast can then be used as a model organism for further testing. [0103] A construct encoding the human variant can be used for expression in a yeast system that has been knocked out of the yeast homolog. For example, the yeast can be genetically engineered to have the gene SER1 knocked out. The yeast is then genetically engineered to express PSAT1 from a nucleic acid as shown in Figure 1. Expression constructs for yeast are known by those of skill in the art and may have a strong yeast promoter/terminator and may comprise a yeast selectable marker cassette. [0104] An assay can then be run to determine the yeast cells growth in comparison to a yeast cell expressing the wild type SER1 or a yeast cell expressing a PSAT1 gene that has no mutations. The biochemical pathway that produces serine is highly conserved between humans and yeast so as to allow yeast to adequately serve as a model organism. Loss of function mutations in any of the three serine biosynthetic genes in humans cause Serine Deficiency Syndrome. In yeast, loss of function of the yeast enzymes produces a quantitative and easily measured trait, poor growth in the absence of serine supplementation. [0105] In some embodiments, any of the assays and methods herein can be applied to any amino acid, metabolic gene, and/or metabolic pathways involving amino acid, for example, the urea cycle and arginine synthesis. Kits and systems [0106] Also provided herein are kits and systems including the cells, expression constructs, and protein sequences provided and described herein as well as written instructions for making and using the same. Thus, for example, provided herein is a kit comprising one or more of: a protein sequence as described herein; an expression construct as described herein; and/or a cell as described herein. Also provided is a system for preparing diploid stains for assaying combinations of genes in a cell as described herein, wherein the cell comprises an expression construct, wherein the construct comprises a nucleic acid encoding a protein sequence as described herein. [0107] A look up table is also provided for use with the system to assess the combination of genes that may indicate deleterious combinations. The look-up table is a table that correlates one form of data to another form, or one or more forms of data to a predicted outcome to which the data is relevant, such as phenotype or trait. For example, a look-up table can comprise a correlation between allelic data for at least one protein that is involved in a metabolic pathway and a particular trait or phenotype, such as a particular disease diagnosis, that an individual who comprises the particular allelic data is likely to display, or is more likely to display than individuals who do not comprise the particular allelic data. Look-up tables can be multidimensional, for example, without being limiting, they can contain information about multiple alleles for a particular protein or proteins simultaneously, or they can contain information about multiple protein variants, such as mutational variants, and they may also comprise other factors, such as particulars about diseases diagnoses, therapeutic methods or drugs to be used with a particular disease. In some embodiments, the look-up table comprises correlations between at least one allele and a disease. In some embodiments, the look-up table comprises a correlation for a plurality of diseases. In all scenarios, by referencing to a look-up table that gives an indication of a correlation between an allele and a metabolic disease, such as a serine deficiency, a disease or predicted progeny can be identified in the individual from whom the sample is derived. In some embodiments, the correlation is reported as a statistical measure. The statistical measure may be reported as a risk measure, such as a relative risk (RR), an absolute risk (AR) or an odds ratio (OR). They can also be reported as a having a pathogenic threshold for the protein, neural threshold or as a variable unknown. [0108] A look-up table may be generated by the individual assessment of alleles or by studies of diploid cells that are made by crossing cells that are homozygous for a normal gene and cells that cells that have the mutated from of the gene that is to be tested. [0109] Kits can be used that provide a look up table, wherein the look up table indicates genes or combinations of genes that may be indicative of an amino acid deficiency or disease and one or more nucleic acid probes for detecting one or more mutation in PSAT, wherein the one or more mutation includes at least: G78A, R213C, T156M, R222. In some embodiments, the kit comprises a supplement. In some embodiments, the supplement is serine that is in an amount sufficient to treat a subject suffering from serine deficiency. Additional embodiments [0110] Urea cycle disorders due to abnormalities in arginine metabolism are much more common than serine deficiencies. [0111] Some embodiments herein relate to establishing yeast functional assays for three genes that are involved in the biosynthesis of arginine (Figure 19). In some embodiments, the yeast functional assays disclosed herein can be applied to one gene in the biosynthesis of arginine. In some embodiments, the yeast functional assays disclosed herein can be applied to two genes in the biosynthesis of arginine. In some embodiments, the yeast functional assays disclosed herein can be applied to three genes in the biosynthesis of arginine. In some embodiments, the yeast functional assays disclosed herein can be applied to more than three genes in the biosynthesis of arginine. [0112] The yeast enzymes in three colinear steps of the arginine biosynthesis pathway are highly conserved with their human orthologs (Table 1). Table 1. Human ORFs. [0113] In humans, this pathway is known as the urea cycle because it is the principal mechanism for the clearance of waste nitrogen resulting from protein turnover and enzyme deficiencies cause urea cycle disorders [1, 2]. [0114] In some embodiments, a method of screening a subject for a disease comprises: [0115] a) obtaining genomic DNA from the subject; [0116] b) identifying a gene of interest from the genomic DNA; [0117] c) inserting the gene into a construct, wherein the construct is a linear DNA; [0118] d) providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell; [0119] e) introducing the construct into the test cell; [0120] f) evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease, [0121] In some embodiments of the method of screening a subject for a disease, the gene of interest is one or more a metabolic gene or a gene(s) from Table 2. Table 2 In some embodiments, the method of screening a subject for a disease involves codon reverse harmonization, as provided in any of the codon embodiments provided herein. In some embodiments, this can be applied to any of the human to yeast orthologs provided herein (e.g., table 2). [0122] In some embodiments of the method of screening a subject for a disease, the subject is a fetus, neonate, juvenile or adult. [0123] In some embodiments of the method of screening a subject for a disease, the cell and the control cell are yeast cells. [0124] In some embodiments of the method of screening a subject for a disease, the amino acid that is being processed is arginine. [0125] In some embodiments of the method of screening a subject for a disease, the subject is pregnant. [0126] In some embodiments of the method of screening a subject for a disease, the gene encodes OTC, ASS1, or ASL. [0127] In some embodiments of the method of screening a subject for a disease, cell growth is measured by optical density of a liquid culture, a number of pixels of a colony or patch of cells growing on solid media, or size a colony or patch of cells growing on solid media. [0128] In some embodiments of the method of screening a subject for a disease, the evaluating step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. [0129] In some embodiments of the method of screening a subject for a disease, cell growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell produces an optical density of a liquid culture, a number of pixels of a colony or patch of cells growing on solid media, or size a colony or patch of cells growing on solid media that is statistically equivalent to the growth value of the control cell. [0130] In some embodiments of the method of screening a subject for a disease, cell growth of the test cell produces an optical density of a liquid culture, a number of pixels of a colony or patch of cells growing on solid media, or size a colony or patch of cells growing on solid media is statistically less than the growth value of the control cell. [0131] In some embodiments of the method of screening a subject for a disease, the gene of interest is further analyzed for a single-nucleotide polymorphism. Without being limited by any particular theory, in some instances, it will be known (before the assay is performed) that the SNP is a loss of function mutation. In other instances, the assay will yield that the SNP results in loss of function. In some embodiments, prior to the assays herein, there will be some alleles that are known to be “pathogenic” (in this case loss of function), those that are “likely benign” (wildtype level of activity), and variants of uncertain significance (VUS). In some embodiments, after the assay, the functional impact of many of these VUS alleles (as loss of function or wildtype) can be assessed. [0132] In some embodiments of the method of screening a subject for a disease, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. [0133] In some embodiments of the method of screening a subject for a disease, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a significant growth difference between the test cell and control cell. [0134] In some embodiments of the method of screening a subject for a disease, the significant growth difference indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. [0135] In some embodiments of the method of screening a subject for a disease, the disease is a Urea Cycle Disorder. Non-limiting examples are provided in Table 0.2. Table 0.2 [0136] In some embodiments of the method of screening a subject for a disease, evaluating further comprises quantifying cell growth by photographing yeast growing on solid agar plates and performing image analysis using a custom software. [0137] In some embodiments, the disease can be one or more amino acid deficiencies that result from a deficiency of one or more essential amino acids that cannot be synthesized de novo by the organism at a rate commensurate with its demand, and thus must be supplied in its diet. Of the 21 amino acids common to all life forms, the nine amino acids that cannot be synthesized by humans are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. [0138] In some embodiments, the disease can be one or more amino acid deficiencies of the amino acids that humans are able to synthesize because some humans (e.g., serine deficiency patients) harbor mutations that do not allow them to make these amino acids. Non-limiting examples of other diseases associated with amino acid metabolism are provided in Table 0.3. Table 0.3

[0139] In some embodiments, custom software used in performing image analysis include, without limitations, ImageJ/FIJI, Cell Profiler/Cell Analyst, Neuronstudio, Volume Integration and Alignment System (VIAS), and L-measure. [0140] In some embodiments, a method of determining an amino acid deficiency in a subject comprises: [0141] a) isolating genomic DNA from a subject; [0142] b) detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway; [0143] c) inserting the gene into a construct; [0144] d) introducing the construct into a test cell; [0145] e) growing up the cell in a media absent of an amino acid; and [0146] f) analyzing growth of the test cell in a culture, wherein the growth of the test cell is compared to a control cell, wherein the control cell is not deficient in amino acid synthesis wherein the test cell growth is compared to the control cell, wherein cell growth of the test cell is comparable to that of the control cell indicates that the gene encodes a functional enzyme and wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene encodes a non-functional protein or protein with decreased function and indicates [0147] In some embodiments of the method of determining amino acid deficiency, the subject is a fetus, neonate, juvenile or adult, wherein the gene is a metabolic gene or a gene from Table 2. [0148] In some embodiments of the method of determining amino acid deficiency, the cell and the control cell are yeast cells. [0149] In some embodiments of the method of determining amino acid deficiency, the amino acid is arginine. [0150] In some embodiments of the method of determining amino acid deficiency, the subject is pregnant. [0151] In some embodiments of the method of determining amino acid deficiency, the gene encodes OTC, ASS1, or ASL. [0152] In some embodiments of the method of determining amino acid deficiency, cell growth is measured by optical density of a liquid culture, a number of pixels of a colony of cells growing on solid media. [0153] In some embodiments of the method of determining amino acid deficiency, the analyzing step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. [0154] In some embodiments of the method of determining amino acid deficiency, cell growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell has an optical density that is at least 90% of the growth value of the control cell. [0155] In some embodiments of the method of determining amino acid deficiency, cell growth of the test cell is slow as compared to the control cell, wherein the cell has an optical density that is 79% or less than the optical density of the control cell. [0156] In some embodiments of the method of determining amino acid deficiency, the gene of interest is further analyzed for a single-nucleotide polymorphism. [0157] In some embodiments of the method of determining an amino acid deficiency, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. [0158] In some embodiments of the method of determining amino acid deficiency, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a significant growth difference between the test cell and control cell. [0159] In some embodiments of the method of determining amino acid deficiency, the significant growth difference indicates that the gene of interest encodes a non- functional protein or protein with decreased function and indicates the disease. [0160] In some embodiments of the method of determining amino acid deficiency, the disease is NLS, Urea Cycle Disorders, retinal neuropathy, or an amino acid deficiency in the subject. [0161] In some embodiments of the method of determining amino acid deficiency, the analyzing step further comprises identifying at least one mutation in the gene. [0162] In some embodiments, a method of determining a carrier of an amino acid deficiency disorder comprises: isolating genomic DNA from a subject; detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway, wherein the subject has two different alleles of the gene; inserting the gene into a construct, wherein the construct is a linear DNA; introducing the construct into a test cell; growing up the test cell in a media absent of an amino acid; and evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein test cell growth is compared to a control cell that has the homologous gene, wherein test cell growth of the cell is comparable to that of the control cell indicates that the gene of interest encodes a functional protein and wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates that the subject is a carrier of an amino acid deficiency disorder, wherein the gene is a metabolic gene or a gene from Table 2. [0163] In some embodiments, of the method of determining a carrier, the amino acid deficiency disorder is NLS. [0164] In some embodiments, a method of treating a subject with an amino acid deficiency comprises: determining a subject or carrier of an amino acid deficiency disorder, wherein the determining comprises: detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway; inserting the gene into a construct, wherein the construct is a linear DNA; introducing the construct into a test cell; growing up the test cell in a media absent of an amino acid; and evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein test cell growth is compared to a control cell that has the homologous gene, wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene of interest encodes a non- functional protein or protein with decreased function and indicates that the subject is a carrier of an amino acid deficiency disorder; providing an adequate amount of an amino acid supplement to the subject, wherein the gene is a metabolic gene or a gene from Table 2. [0165] In some embodiments of the method of treating a subject, the amino acid supplement is arginine. [0166] In some embodiments of the method of treating a subject, the enzyme is wherein the gene encodes OTC, ASS1, or ASL. [0167] In some embodiments of the method of treating a subject, the subject is a fetus and wherein the mother of the fetus is provided an adequate amount of amino acid supplement. [0168] In some embodiments of the method of treating a subject, evaluating further comprises comparing growth of the test cell to a second control cell, wherein the second control cell is deficient in arginine biosynthesis. [0169] In some embodiments of the method of treating a subject, the amino acid deficiency disorder is NLS. [0170] In some embodiments, a method of prenatal prediction of an amino acid deficiency comprises: obtaining genomic DNA from a female and male subject; identifying a same gene of interest from the genomic DNA of the female and male subject, wherein the subjects are homozygous or heterozygous for the gene; inserting a first gene variant of interest from the female into a first construct, wherein the first construct is a linear DNA; inserting a second gene variant of interest from the male into a second construct, wherein the second construct is a linear DNA; providing a first cell, wherein the first cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell; providing a second cell, wherein the second cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell; introducing the first construct into the first cell, wherein the first construct is a linear DNA; introducing the second construct into the second cell, wherein the second construct is a linear DNA; and evaluating the first and second cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the first and second cell are compared to a control cell that has the homologous gene, wherein cell growth of the first and/or second cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the first and second cell is slow as compared to the control cell indicates that the first and second gene of interest encodes a non-functional protein or protein with decreased function and indicates that the male and/or female is a carrier of a disease for an amino acid deficiency, wherein the same gene of interest is a metabolic gene or a gene from Table 2. [0171] In some embodiments, the method of prenatal prediction of an amino acid deficiency further comprises making a diploid strain of a third cell, wherein the third cell comprises the first and second gene of interest and evaluating the third cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the third cell are compared to a control cell that has the homologous gene, wherein cell growth of the third cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the third cell is slow as compared to the control cell indicates that the first and second gene of interest together indicates a predicted fetus with an amino acid deficiency. [0172] In some embodiments of the method of prenatal prediction of an amino acid deficiency, data from the first, second and third cell is stored in a look-up table, wherein the look-up table is generated for disease prediction. [0173] In some embodiments of the method of prenatal prediction of an amino acid deficiency, the disease for an amino acid deficiency is NLS. [0174] In some embodiments, a method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation comprises: a) obtaining genomic DNA from a female and male subject; b) identifying a same gene of interest from the genomic DNA of the female and male subject, wherein the subjects are homozygous or heterozygous for the gene; c) inserting a first gene of interest from the female into a first construct; d) inserting a second gene of interest from the male into a second construct; e) providing a first cell, wherein the first cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell; f) providing a second cell, wherein the second cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell; g) making a diploid strain of a third cell, wherein the third cell comprises the first and second gene of interest; h) introducing the first construct into the first cell, wherein the first construct is a linear DNA; i) introducing the second construct into the second cell, wherein the second construct is a linear DNA; and j) evaluating the first, second, and third cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the first and second cell are compared to a control cell that has the homologous gene, wherein cell growth of the first, second and third cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the first, second and third cell is slow as compared to the control cell indicates that the first and second gene of interest encodes a non-functional protein or protein with decreased function and predicts an amino acid deficiency for progeny, wherein the same gene of interest is a metabolic gene or a gene from Table 2. [0175] In some embodiments of the method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation, the first gene of interest or the second gene of interest comprises the gene mutation. [0176] In some embodiments of the method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation, the gene of interest encodes OTC, ASS1, or ASL. [0177] In some embodiments of the method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation, the gene of interest encodes OTC, ASS1, or ASLwith at least one of the amino mutations otc-R141Q, ass1-R127W, asl- Q286R . [0178] In some embodiments of the method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation, data from the first, second and third cell is stored in a look-up table, wherein the look-up table is generated for disease prediction. [0179] In some embodiments of the method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation, the amino acid deficiency is caused by NLS. [0180] In some embodiments, a kit for determining amino acid deficiency comprises: a look-up table, wherein the look up table indicates genes or combinations of genes that may be indicative of an amino acid deficiency or disease; one or more nucleic acid probes for detecting one or more mutation in OTC, ASS1, or ASL, wherein the one or more mutation includes at least: otc-R141Q, ass1-R127W, asl-Q286R. [0181] In some embodiments, the kit further comprising a arginine supplement in an amount sufficient to treat a subject suffering from arginine deficiency (e.g., Urea Cycle Disorders). [0182] In some embodiments, a method of determining if a subject is suffering from an amino acid deficiency comprises: providing a look-up table, wherein the look-up table comprises genes or a combination of genes that are indicative of a disease; isolating genes of interest from a subject; determining if the genes include one of more mutations in the look-up table; and determining a probability of disease in the subject, wherein the genes or a combination of genes are metabolic genes or genes from Table 2. [0183] In some embodiments of the method of determining if a subject is suffering from an amino acid deficiency, the look up table comprises combination of genes that include genes of OTC, ASS1, or ASL, wherein the OTC, ASS1, or ASL genes encode OTC, ASS1, or ASL comprising mutations otc-R141Q, ass1-R127W, asl-Q286R. [0184] In some embodiments of the method of determining if a subject is suffering from an amino acid deficiency, the look up table comprises a list of mutations that have been determined by the method of claim 43, said method further comprising administering an amino acid supplement to the subject to treat the amino acid deficiency if the subject has more than a 50% probability of having the amino acid deficiency. [0185] In some embodiments, a method of treating a subject with an amino acid deficiency comprises: a) determining if a subject has at least one mutation in OTC, ASS1, or ASL located at otc-R141Q, ass1-R127W, asl-Q286R; and b) providing an adequate amount of a arginine supplement to the subject if the subject has the at least one mutation. [0186] In some embodiments of the method of treating a subject with an amino acid deficiency, the at least one mutation is otc-R141Q, ass1-R127W, asl-Q286R, and wherein the subject is an unborn child of a mother, wherein the mother is tested for the presence of the at least one mutation. [0187] In some embodiments, a method of identifying a point mutation as a cause or marker of an amino acid deficiency comprises: obtaining genomic DNA from a subject having the amino acid deficiency; identifying a point mutation in the genomic DNA in at least one of OTC, ASS1, or ASL; providing a test yeast cell, wherein a homologous gene of at least one of OTC, ASS1, or ASL has been knocked out of the test yeast cell; introducing the gene with the point mutation into the test yeast cell; and evaluating the test yeast cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test yeast cell growth is compared to a control cell that has the homologous gene, wherein when test yeast cell growth is comparable to that of the control cell it indicates that the point mutation still allows for a functional protein, and wherein when the test yeast cell growth is slow as compared to the control cell it indicates that the point mutation results in a non-functional protein or protein with decreased function, thereby identifying the point mutation as a cause or marker of an amino acid deficiency. [0188] In some embodiments, a method of preparing a personalized yeast model for determining a subject at risk of a disease comprises: a) obtaining genomic DNA from the subject; b) identifying a gene of interest in at least two alleles from the genomic DNA; c) inserting the gene into a construct, wherein the construct is a linear DNA; d) providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell; e) introducing the construct into the test cell; f) evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease; g) generating data for a look-up table; and h) generating one or more personalized disease amelioration recommendations for the subject; and presenting the one or more personalized disease prevention recommendations for the subject in the personalized disease prevention plan for the subject for disease management, wherein the gene of interest is a metabolic gene or a gene from Table 2. [0189] In some embodiments of the method of preparing a personalized yeast model, the method further comprising: a) obtaining a second genomic DNA from a second subject, wherein the second subject has a second set of two alleles that are related to the two alleles of the subject, and second set of two alleles have a second gene of interest, wherein the second gene of interest is placed in a second construct b) introducing the second construct into a second test cell, evaluating the second test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when second test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function. [0190] In some embodiments, the method of preparing a personalized yeast model further comprising obtaining a second genomic DNA from a second subject and identifying a second gene(s) of interest in at least two alleles from the genomic DNA, inserting at least one of the second gene(s) into a second construct, introducing the second construct into a second test cell, and mating the second cell with the first cell to produce a progeny cell. [0191] In some embodiments, the method of preparing a personalized yeast model further comprising evaluating the progeny cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when progeny cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the progeny cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. [0192] In some embodiments, any and/or all of the methods provided herein can employ the following codon optimization. Reverse harmonization [0193] Some embodiments herein relate to methods for codon harmonization in which the codons of a heterologous protein coding sequence are altered to more closely match the usage frequency of the codons in orthologous positions of the host organism’s orthologous gene, even if the amino acids encoded at those position differ between the two orthologs. [0194] Some embodiments herein relate to methods of selecting codons for optimization of a sequence involving a process that is the opposite/reverse of the normal harmonization method (“reverse harmonization”). [0195] Without being limited by any particular theory, most heterologous expression strategies are focused on the goal of expressing as much of the protein as possible. Thus, these strategies often use really strong promoters to express high levels of mRNA and codon optimization that replaces rare codons with more frequently used ones. In some embodiments, an innovative aspect of the methods of codon optimization herein is to not try and make the most possible as fast as possible. Without being limited by any particular theory, it is believed that the host (e.g., yeast) regulatory sequences (transcriptional promoters, transcriptional terminators, RNA stability elements, and rates of translation, i.e., codon usage) have evolved to make the optimal amount of a given protein/enzyme under a given environmental condition. Furthermore, without being limited by any particular theory, it is believed that if the optimal amount of a given protein/enzyme that the host needs is made, the assay for the function of that protein/enzyme (e.g., yeast growth) will work better. Thus, these aspects can be applied in one or more of the reverse harmonization methods provided herein. [0196] In some embodiments, reverse harmonization involves selecting one or more cDNAs from a first organism to be codon optimized with respect to its ortholog from a second organism. In some embodiments, the cDNA from the first organism to be codon optimized is aligned (for example, using a alignment tool such as Clustal Omega) to its ortholog from the second organism. The protein sequence encoded by the cDNA from the first organism to be codon optimized is also aligned with the protein sequence encoded by its ortholog from the second organism. [0197] In some embodiments, a method of codon optimization by reverse harmonization comprises obtaining a sequence of a first gene/cDNA to be optimized from a first organism; obtaining a sequence of a second gene/cDNA from a second organism, wherein the second gene/cDNA is an ortholog of the first gene/cDNA, and the first gene/cDNA is to be optimized for expression in the second organism; performing a first alignment of the first and second gene/cDNA sequences; obtaining a protein sequence encoded by the a first gene/cDNA; obtaining a protein sequence encoded by the second gene/cDNA; performing a second alignment of the protein sequences encoded by the firs tan d second gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in the first and second gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in the first gene/cDNA with the codon in the second gene/cDNA, if the codons in the first and second gene/cDNA that encode the same amino acid at mutually corresponding positions in the second alignment are different between the first and second gene/cDNA, thereby obtaining a codon optimized first gene/cDNA from the first organism. [0198] In some embodiments, the method of codon optimization by reverse harmonization further comprises identifying positions in the first alignment where codons differ between the first and the second genes/DNA; and replacing codons in the first gene/cDNA lacking corresponding codons in the second gene/cDNA by selecting codons from the second organism that encode the same amino acid. [0199] In some embodiments of the method of codon optimization by reverse harmonization, selecting codons from the second organism is based on a frequency of usage of a codon encoding a particular amino acid in the second organism. [0200] In some embodiments of the method of codon optimization by reverse harmonization, the frequency of usage of a codon encoding a particular amino acid in the second organism is the same or approximately the same as the frequency of usage of a codon encoding a particular amino acid in the first organism. For example, the frequency of usage of a codon encoding a particular amino acid is 10% in both the first and second organisms. In some embodiments, when the frequency of usage of a codon encoding a particular amino acid is approximately same between the first and second organism, the frequency of usage of a codon encoding a particular amino acid can vary by about ±10% between the two organisms (Tables 0.4 and 0.5). In some embodiments, the frequency of usage of a codon encoding a particular amino acid can vary by about ±20% between the two organisms (Tables 0.4 and 0.5). In some embodiments, the frequency of usage of a codon encoding a particular amino acid can vary by about ±30% between the two organisms (Tables 0.4 and 0.5). In some embodiments, the frequency of usage of a codon encoding a particular amino acid can vary by about ±40% between the two organisms (Tables 0.4 and 0.5). In some embodiments, the frequency of usage of a codon encoding a particular amino acid can vary by about ±50% between the two organisms (Tables 0.4 and 0.5). In some embodiments, the frequency of usage of a codon encoding a particular amino acid can vary by about ±60% between the two organisms (Tables 0.4 and 0.5). [0201] n some embodiments of the method of codon optimization by reverse harmonization, the frequency of usage of a codon encoding a particular amino acid in the second organism is different than the frequency of usage of a codon encoding a particular amino acid in the first organism. For example, the frequency of usage of a codon encoding a particular amino acid is 10% in the first organism, and the frequency of usage of a codon encoding the same amino acid is 30% in the second organism. [0202] In some embodiments of the method of codon optimization by reverse harmonization, a protein encoded by the codon optimized first gene/cDNA is expressed more efficiently and/or at a higher level in the second organism as compared to a codon non- optimized first gene/cDNA. In some embodiments, the protein is expressed at higher levels. [0203] For example, in some embodiments, reverse harmonization involves selecting one or more human cDNAs to be codon optimized with respect to its yeast ortholog. In some embodiments, the human cDNA to be codon optimized is aligned with its yeast ortholog. The protein sequence encoded by the human cDNA to be codon optimized is also aligned with the protein sequence encoded by its yeast ortholog. For positions that encode the same amino acids in the alignment, if the human codons encoding those amino acids are different from the corresponding yeast codons for those amino acids, the human codons encoding those amino acids are replaced with the corresponding yeast codons for those amino acids. Thereafter, for the remaining amino acid positions that align between the two sequences, the frequency of usage of the codon/codons for a particular amino acid in the human sequence is compared to the frequency of usage of the same codon in yeast. For any codon comparisons where the codons are different and the frequency of occurrence of the codons are different between the organisms, one will alter the codon used in the foreign gene so that it has the same frequency of occurrence as the gene in the host organism. Thus, if a first amino acid in the host gene is different from a first amino acid in the foreign gene, one determines the frequency of occurrence of the codon in the host gene (e.g., 20%) and then selects a codon for the foreign gene that still encodes for the first amino acid of the foreign gene, but has a frequency of occurrence in the host that is closest to 20%. The goal of this optimization is to achieve a rate of translation of the foreign protein that is close to that of the orthologous ”native” protein in the host. [0204] In some embodiments, the protein encoded by the codon optimized first gene/cDNA is a protein expressed more efficiently and at a higher level in the second organism for an application selected from the group consisting of, without limitations, beer production, wine production, baking, bioremediation, oil remediation, industrial ethanol production, production of nutritional supplements, production of probiotics, protein expression for biochemical and/or biophysical research, and protein therapy. In some embodiments of the method of codon optimization by reverse harmonization, the protein encoded by the codon optimized first gene/cDNA is a protein expressed more efficiently and at a higher level in the second organism for an application selected from the group consisting of biofuel production, antibody screening, and/or antibody production. [0205] In some embodiments of the method of codon optimization by reverse harmonization, about 1% to about 50% of the first gene/cDNA is codon optimized. In some embodiments, about 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55% of the first gene/cDNA is codon optimized. In some embodiments, more than about 50% of the first gene/cDNA is codon optimized. [0206] In some embodiments, positions where both human and yeast cDNAs encode the same amino acid can be identified. [0207] In some embodiments, codons in the human cDNA can be replaced with the yeast codon used at that position in the alignment, if the human and yeast codons are different, and if the amino acid at that position is identical between the two organisms. [0208] In some embodiments, for the remaining amino acids positions that align between the two sequences (e.g. not in gaps), it can be checked whether the frequency of codon in humans is comparable to the frequency of that codon in yeast. [0209] Some embodiments herein relate to methods of reverse harmonization of codons. Some embodiments herein relate to methods of reverse harmonization of codon of human genes. Some embodiments herein relate to methods of reverse harmonization of codon of human genes for expressing in yeast. [0210] In some embodiments, the methods of codon harmonization outperform the native human gene/cDNA and/or some other publicly available codon optimization algorithms. [0211] Figure 20 show an embodiment of a codon harmonization method described herein. In some embodiments, human cDNA and yeast cDNA sequences (both products of nature) for two orthologous genes are aligned (Figures 20-28). In some embodiments, any of these genes or gene pairs can be used in any one or more of the embodiments provided herein. Figures 21, 23, 25, and 27 also include the recoded sequence in line with the reverse harmonization aspects provided herein. [0212] Figure 29 shows an embodiment of a codon optimized ASL protein coding nucleotide sequence (SEQ ID NO: 24) generated after the harmonization method and associated software herein. This “recoded” sequence is a non-limiting illustrative example of a sequence that would be generated using an embodiment of the codon optimization method disclosed herein. In some embodiments, publicly available software (e.g., by IDT) can be used to generate a sequence for testing. [0213] Figure 30 shows another embodiment a codon optimized ASL protein coding nucleotide sequence (SEQ ID NO: 21) generated after the harmonization method and associated software herein. [0214] In some embodiments, there will be regions (gaps) where there is additional sequence (resulting in extra amino acids) in one of the two sequences. These codons are not altered from the human cDNA sequence. [0215] In some embodiments, positions where both human and yeast cDNAs encode the same amino acid can be identified. For these amino acid positions, the yeast codon is used. [0216] In some embodiments, codons in the human and yeast cDNAs encode different amino acids at the same position. In this case, the human amino acid is maintained, but where possible its codon is replaced with a codon whose usage frequency closely matches the usage frequency of the yeast codon at that position.. [0217] In some embodiments, for the remaining amino acids positions that align between the two sequences (e.g. not in gaps), it can be checked whether the frequency of codon in humans is comparable to the frequency of that codon in yeast. [0218] If codon usage frequencies is not the same between the two species, then in some embodiments, the codon in the human cDNA can be changed to a codon (for the same amino acid) that is closer to the yeast frequency. In some embodiments, changing one or more codons in the human cDNA to one or more codons (for the same amino acid) that is closer to the yeast frequency results in a robust expression of the human gene in the yeast. [0219] Table 0.4 shows a non-limiting examples of yeast codon usage frequency values. Tables 0.4 and 0.5 can be used in one or more of the condon harmonization methods provided herein. If other organisms are the source or destination, then the appropriate frequencies can be employed. Table 0.4

[0220] Table 0.5 shows a non-limiting examples of human codon usage frequency values. Table 0.5

[0221] In an example, the CAG codon, which encodes Glutamine (Q) and has a high frequency of usage in humans (CAG = 34.6; Table 0.5), can be substituted in a human cDNA to be expressed in yeast with the CAA codon, because CAA, which also encodes Glutamine (Q), has a higher frequency of usage in yeast (27.5; Table 0.4) as compared to CAG (12.2; Table 0.4). [0222] In some embodiments, the gene to be altered is a human gene to be inserted into any one of the following organisms yeast, bacteria, xenopus, insect cells, fish, worms, flies, and/or in vitro cell culture derivatives of any of these organisms. [0223] In some embodiments, the gene to be altered is a plant gene, to be inserted into any one of the following organisms yeast, bacteria, xenopus, insect cells, fish, worms, flies, human cells, and/or in vitro cell culture derivatives of any of these organisms. The plant can be any one or more of fruits, vegetables, flowers, and the like. Additional embodiments Analysis of yeast on solid agar plates [0224] In a first aspect, a method of screening a subject for a disease is provide. The method comprises the steps: obtaining genomic DNA from the subject, identifying a gene of interest from the genomic DNA, inserting the gene into a construct, wherein the construct is a linear DNA, providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell, introducing the construct into the test cell, evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments, the media is solid agar. In some embodiments, the evaluating further comprises quantifying cell growth by photographing yeast growing on solid agar plates and performing image analysis using a custom software. [0225] An analysis may be performed by taking pictures once every 12 hours over the course of 3 days to 5 days, for example. Alternatively, pictures of the agar plates may also be taken every 30 minutes over the course of 3 days. In these cases, at least one time point in that time course (an end point analysis) may be used or several time points may be used to calculate the change in the cell growth over time. [0226] In some embodiments, the media is a liquid media. In some embodiments, the subject is a fetus, neonate, juvenile or adult. In some embodiments, the cell and the control cell are yeast cells. In some embodiments, the amino acid is serine. In some embodiments, the subject is pregnant. In some embodiments, the gene encodes 3-PGDH, PSAT1 or PSPH. In some embodiments, cell growth is measured by optical density. In some embodiments, the evaluating step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. In some embodiments, cell growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell has an optical density that is at least 90% of the growth value of the control cell. In some embodiments, cell growth of the test cell is slow as compared to the control cell, wherein the cell has an optical density that is 79% or less than the optical density of the control cell. In some embodiments, the gene of interest is further analyzed for a single-nucleotide polymorphism. In some embodiments, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. In some embodiments, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a significant growth difference between the test cell and control cell. In some embodiments, the significant growth difference indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments, the disease is NLS, Serine Deficiency Syndrome or retinal neuropathy. In some embodiments, the evaluating further comprises quantifying cell growth by photographing yeast growing on solid agar plates and performing image analysis using a custom software. Methods and generation of a look up table. [0227] Also contemplated are methods to prepare the look up table in order to generate a prenatal prediction for progeny. The data for predicting a disease in a subject that is a fetus, neonatal, juvenile and adult may be obtained by the methods described herein. This data may be used in a look-up table to predict the phenotypic outcome of a fetus based on the personalized yeast model of both parents and may also be used on a human of any age to determine future health issues, such as adult onset metabolic deficiencies, such as retinal neuropathy. The methods here provide the steps of obtaining genomic DNA from one or two subjects in order to analyze the gene of interest in a test for either haploid cells or diploid cells depending on whether one would like to test one or both of the alleles that have the gene of interest. Thus one can predict the function of a single gene or the effects of having a wild type gene and a mutational recessive as well as a double recessive. The results can then be analyzed to generate a table to correlate certain combinations of genes to a disease and this may be used to develop a therapeutic based on the personalized yeast model results. Measurement of cell growth [0228] In some embodiments, cell growth, may also be referred to as the “growth value”, is measured by optical density of a liquid culture. In some embodiments, cell growth, also the “growth value”, is measured by the area of a “patch” or “spot” of cells growing on solid media, the number of pixels of a “patch” or “spot” of cells growing on solid media, the intensity of the pixels in a “patch” or “spot” of cells growing on solid media, the change in any of these parameters over time, or a combination of any of the afore mentioned parameters. Measurement of the cell growth in a solid media may be measured by photographing yeast growing on solid agar plates and performing image analysis using custom software. Screening a subject for disease [0229] A method of screening a subject for a disease or being a carrier for a disease is provided. The method comprises the steps: obtaining genomic DNA from the subject, identifying a gene of interest from the genomic DNA, inserting the gene into a construct, wherein the construct is a linear DNA, providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell, introducing the construct into the test cell, evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments, the subject is a fetus, neonate, juvenile or adult. In some embodiments, the cell and the control cell are yeast cells. In some embodiments, the amino acid is serine. In some embodiments, the subject is pregnant. In some embodiments, the gene encodes 3-PGDH, PSAT1 or PSPH. In some embodiments, cell growth, hereafter the “growth value”, is measured by optical density of a liquid culture. In some embodiments, cell growth, also the “growth value”, is measured by the area of a “patch” or “spot” of cells growing on solid media, the number of pixels of a “patch” or “spot” of cells growing on solid media, the intensity of the pixels in a “patch” or “spot” of cells growing on solid media, the change in any of these parameters over time, or a combination of any of the aforementioned parameters. In some embodiments, the evaluating step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. In some embodiments, growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell has a growth value that is at least 90% of the growth value of the control cell. In some embodiments, cell growth of the test cell is slow as compared to the control cell, wherein the cell has an optical density or growth value that is 79% or less than the growth value of the control cell. The measurement may be performed by analyzing cell growth on a solid media, thus the measurement is performed by analysis of pixels in a “patch” or “spot” of cells growing on solid media, the change in any of these parameters over time. This cell growth can be measured against a control cell that is carrying a wild type PSAT1 gene. The growth is measured to find thresholds for a severe form of a metabolic disease (e.g. NLS). Milder forms of the disease such as adult onset diseases are likely to have a different threshold than those suffering from a severe form of the disease. [0230] In some embodiments, the gene of interest is further analyzed for a single- nucleotide polymorphism. In some embodiments, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. In some embodiments, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a highly significant growth difference between the test cell and control cell. In some embodiments, the significant growth difference indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments, the disease is NLS, Serine Deficiency Syndrome or retinal neuropathy. In some embodiments, the evaluating further comprises quantifying cell growth by photographing yeast growing on solid agar plates and performing image analysis using custom software. [0231] Cell growth, may also be referred to as the “growth value”, and may be measured by optical density of a liquid culture. In some embodiments, cell growth, also the “growth value”, is measured by the area of a “patch” or “spot” of cells growing on solid media, the number of pixels of a “patch” or “spot” of cells growing on solid media, the intensity of the pixels in a “patch” or “spot” of cells growing on solid media, the change in any of these parameters over time, or a combination of any of the aforementioned parameters. [0232] [0274] The biochemical pathway that produces serine is nearly identical between humans and yeast. Loss of function mutations in any of the three serine biosynthetic genes in humans cause Serine Deficiency Syndrome. In yeast, loss of function of the yeast enzymes produces a quantitative and easily measured trait, poor growth in the absence of serine supplementation. In the embodiments herein, it is shown that the human protein coding sequence of the PSAT1 gene can functionally replace the corresponding SER1 gene in yeast. Thus the yeast-based assay described in the embodiments for measuring the activity of PSAT1 gene variants found in a specific patient may be used as part of the protocol for assessing the clinical significance of a genetic variant (Richards, S., et al., Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genetics in medicine : official journal of the American College of Medical Genetics 17, 405-424, 2015, which is hereby incorporated by reference in its entirety) or for other types of genetic analyses, such as genome-wide association studies (GWAS).. [0233] In a first aspect, a method of screening a subject for a disease is provided. The method comprises the steps: obtaining genomic DNA from the subject, identifying a gene of interest from the genomic DNA, inserting the gene into a construct, wherein the construct is a linear DNA, providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell, introducing the construct into the test cell, evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments, the subject is a fetus, neonate, juvenile or adult. In some embodiments, the cell and the control cell are yeast cells. In some embodiments, the amino acid is serine. In some embodiments, the subject is pregnant. In some embodiments, the gene encodes 3-PGDH, PSAT1 or PSPH. In some embodiments, cell growth is measured by optical density of a liquid culture, or a number of pixels of a colony of cells growing on solid media.. In some embodiments, wherein the evaluating step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. In some embodiments, growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell has a growth value that is at least 90% of the growth value of the control cell. In some embodiments, cell growth of the test cell is slow as compared to the control cell, wherein the cell has an optical density that is 79% or less than the growth value of the control cell. In some embodiments, the gene of interest is further analyzed for a single-nucleotide polymorphism. In some embodiments, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. In some embodiments, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a highly significant growth difference between the test cell and control cell. In some embodiments, the significant growth difference indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. In some embodiments, the disease is NLS, Serine Deficiency Syndrome or retinal neuropathy. In some embodiments, the evaluating further comprises quantifying cell growth by photographing yeast growing on solid agar plates and performing image analysis using custom software. [0234] In a second aspect, a method of determining amino acid deficiency in a subject is provided. The method comprises the steps: isolating genomic DNA from a subject, detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway, inserting the gene into a construct, introducing the construct into a test cell, growing up the cell in a media absent of an amino acid and analyzing growth of the test cell in a culture, wherein the growth of the test cell is compared to a control cell, wherein the control cell is not deficient in amino acid synthesis wherein the test cell growth is compared to the control cell, wherein cell growth of the test cell is comparable to that of the control cell indicates that the gene encodes a functional enzyme and wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene encodes a non- functional protein or protein with decreased function and indicates The method of claim 1, wherein the subject is a fetus, neonate, juvenile or adult. In some embodiments, the cell and the control cell are yeast cells. In some embodiments, the amino acid is serine. In some embodiments, the subject is pregnant. In some embodiments, the gene encodes 3-PGDH, PSAT1 or PSPH. In some embodiments, cell growth is measured by optical density. In some embodiments, the analyzing step comprises measuring cell growth for 0.5, 2, 4, 6, 8, 10, 12, 24, 36, 72, 96 or 120 hours or any number of hours in between a range defined by any two aforementioned values. [0235] In some embodiments, a patient DNA is not required and the only information required is what sequence polymorphisms the patient has. In some embodiments, such information can be obtained from clinical geneticists, the scientific literature, or public and private databases. [0236] In some embodiments, cell growth of the test cell is comparable to that of the control cell by automated image analysis, wherein the test cell has a growth value that is at least 90% of the growth value of the control cell. In some embodiments, cell growth of the test cell is slow as compared to the control cell, wherein the cell has a growth value that is 79% or less than the optical density of the control cell. [0237] In some embodiments, the gene of interest is further analyzed for a single- nucleotide polymorphism. In some embodiments, the single-nucleotide polymorphism is identified as being associated with loss of function or decreased function of a protein encoded by the gene of interest. [0238] In some embodiments, a t-test is performed between the test cell and control cell to examine significant growth difference, wherein a t-test p-values < 0.0001 indicates a highly significant growth difference between the test cell and control cell. In some embodiments, the significant growth difference indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. [0239] In some embodiments, the disease is NLS, Serine Deficiency Syndrome or retinal neuropathy or an amino acid deficiency in the subject. [0240] In some embodiments, the analyzing step further comprises identifying at least one mutation in the gene. [0241] In a third aspect, a method of determining a carrier of an amino acid deficiency disorder is provided. The method comprises the steps: isolating genomic DNA from a subject, detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway, wherein the subject has two different alleles of the gene, inserting the gene into a construct, wherein the construct is a linear DNA, introducing the construct into a test cell, growing up the test cell in a media absent of an amino acid and evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein test cell growth is compared to a control cell that has the homologous gene, wherein test cell growth of the cell is comparable to that of the control cell indicates that the gene of interest encodes a functional protein and wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene of interest encodes a non- functional protein or protein with decreased function and indicates that the subject is a carrier of an amino acid deficiency disorder. In some embodiments, the amino acid deficiency disorder is NLS. [0242] In a fourth aspect, a method of treating a subject with an amino acid deficiency is provided. The method comprises the steps: determining a subject or carrier of an amino acid deficiency disorder, wherein the determining comprises: detecting a gene from the genomic DNA, wherein the gene encodes an enzyme of an amino acid synthesis pathway; inserting the gene into a construct, wherein the construct is a linear DNA; introducing the construct into a test cell; growing up the test cell in a media absent of an amino acid; and evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein test cell growth is compared to a control cell that has the homologous gene, wherein cell growth of the test cell is slow as compared to the control cell indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates that the subject is a carrier of an amino acid deficiency disorder; and providing an adequate amount of an amino acid supplement to the subject. In some embodiments, the amino acid supplement is serine. In some embodiments, the enzyme is wherein the gene encodes 3-PGDH, PSAT1 or PSPH. In some embodiments, the subject is a fetus and wherein the mother of the fetus is provided an adequate amount of amino acid supplement. In some embodiments, the evaluating further comprises comparing growth of the test cell to a second control cell, wherein the second control cell is deficient in serine biosynthesis. In some embodiments, the amino acid deficiency disorder is NLS. [0243] In a fifth aspect, a method of prenatal prediction of an amino acid deficiency is provided. The method comprises the steps: a) obtaining genomic DNA from a female and male subject, identifying a same gene of interest from the genomic DNA of the female and male subject, wherein the subjects are homozygous or heterozygous for the gene, inserting a first gene variant of interest from the female into a first construct, wherein the first construct is a linear DNA, inserting a second gene variant of interest from the male into a second construct, wherein the second construct is a linear DNA, providing a first cell, wherein the first cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell, providing a second cell, wherein the second cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell, introducing the first construct into the first cell, wherein the first construct is a linear DNA, introducing the second construct into the second cell, wherein the second construct is a linear DNA and evaluating the first and second cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the first and second cell are compared to a control cell that has the homologous gene, wherein cell growth of the first and/or second cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the first and second cell is slow as compared to the control cell indicates that the first and second gene of interest encodes a non-functional protein or protein with decreased function and indicates that the male and/or female is a carrier of a disease for an amino acid deficiency. In some embodiments, the method further comprises making a diploid strain of a third cell, wherein the third cell comprises the first and second gene of interest and evaluating the third cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the third cell are compared to a control cell that has the homologous gene, wherein cell growth of the third cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the third cell is slow as compared to the control cell indicates that the first and second gene of interest together indicates a predicted fetus with an amino acid deficiency. In some embodiments, data from the first, second and third cell is stored in a look-up table, wherein the look-up table is generated for disease prediction. In some embodiments, the disease for an amino acid deficiency is NLS. [0244] In a sixth aspect, a method of method of prenatal prediction of an amino acid deficiency wherein at least one parent has a gene mutation is provided. The method comprises the steps: obtaining genomic DNA from a female and male subject, identifying a same gene of interest from the genomic DNA of the female and male subject, wherein the subjects are homozygous or heterozygous for the gene, inserting a first gene of interest from the female into a first construct, inserting a second gene of interest from the male into a second construct, providing a first cell, wherein the first cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell, providing a second cell, wherein the second cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the cell, making a diploid strain of a third cell, wherein the third cell comprises the first and second gene of interest, introducing the first construct into the first cell, wherein the first construct is a linear DNA, introducing the second construct into the second cell, wherein the second construct is a linear DNA and evaluating the first, second, and third cell for cell growth in a media, wherein the media lacks an amino acid, wherein the cell growth of the first and second cell are compared to a control cell that has the homologous gene, wherein cell growth of the first, second and third cell is comparable to that of the control cell indicates that the first and second gene of interest encodes a functional protein and wherein cell growth of the first, second and third cell is slow as compared to the control cell indicates that the first and second gene of interest encodes a non-functional protein or protein with decreased function and predicts an amino acid deficiency for progeny. In some embodiments, the first gene of interest or the second gene of interest comprises the gene mutation. In some embodiments, the gene of interest encodes PSAT. In some embodiments, the gene of interest encodes PSAT1 with at least one of the amino mutations A99V, S179L, T156M, G78A, R213C or R222. In some embodiments, data from the first, second and third cell is stored in a look-up table, wherein the look-up table is generated for disease prediction. In some embodiments, the amino acid deficiency is caused by NLS. [0245] In a seventh aspect, a kit for determining amino acid deficiency is provided. The kit comprises a look-up table, wherein the look up table indicates genes or combinations of genes that may be indicative of an amino acid deficiency or disease, one or more nucleic acid probes for detecting one or more mutation in PSAT, wherein the one or more mutation includes at least: G78A, R213C, T156M or R222. In some embodiments, the kit comprises a serine supplement in an amount sufficient to treat a subject suffering from serine deficiency. [0246] In an eighth aspect, a method of determining if a subject is suffering from an amino acid deficiency is provided. The method comprises the steps: providing a look-up table, wherein the look-up table comprises genes or a combination of genes that are indicative of a disease, isolating genes of interest from a subject, determining if the genes include one of more mutations in the look-up table and determining a probability of disease in the subject. In some embodiments, the look up table comprises combination of genes that include genes of PSAT, wherein the PSAT genes encode PSAT comprising mutations G78A, R213C, T156M or R222. In some embodiments, the look up table comprises a list of mutations that have been determined by the method of claim 43, said method further comprising administering an amino acid supplement to the subject to treat the amino acid deficiency if the subject has more than a 50% probability of having the amino acid deficiency. [0247] In a ninth aspect, a method of treating a subject with an amino acid deficiency is provided. The method comprises the steps: determining if a subject has at least one mutation in PSAT located at G78, R213, T156 or R222 and providing an adequate amount of a serine supplement to the subject if the subject has the at least one mutation. In some embodiments, the at least one mutation is G78A, R213C, T156M or R222, and wherein the subject is an unborn child of a mother, wherein the mother is tested for the presence of the at least one mutation. [0248] In a tenth aspect, a method of identifying a point mutation as a cause or marker of an amino acid deficiency is provided. The method comprises the steps: obtaining genomic DNA from a subject having the amino acid deficiency, identifying a point mutation in the genomic DNA in at least one of 3-PGDH, PSAT1 or PSPH, providing a test yeast cell, wherein a homologous gene of at least one of 3-PGDH, PSAT1 or PSPH has been knocked out of the test yeast cell, introducing the gene with the point mutation into the test yeast cell and evaluating the test yeast cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test yeast cell growth is compared to a control cell that has the homologous gene, wherein when test yeast cell growth is comparable to that of the control cell it indicates that the point mutation still allows for a functional protein, and wherein when the test yeast cell growth is slow as compared to the control cell it indicates that the point mutation results in a non-functional protein or protein with decreased function, thereby identifying the point mutation as a cause or marker of an amino acid deficiency. [0249] In an eleventh aspect, a method of preparing a personalized yeast model for determining a subject at risk of a disease is provided. The method comprises the steps: obtaining genomic DNA from the subject, identifying a gene of interest in at least two alleles from the genomic DNA, inserting the gene into a construct, wherein the construct is a linear DNA;, providing a test cell, wherein the test cell has a homologous gene of the gene of interest, wherein the homologous gene has been knocked out of the test cell, introducing the construct into the test cell, evaluating the test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease, generating data for a look-up table; and generating one or more personalized disease amelioration recommendations for the subject; and presenting the one or more personalized disease prevention recommendations for the subject in the personalized disease prevention plan for the subject for disease management. In some embodiments, the method further comprising: a) obtaining a second genomic DNA from a second subject, wherein the second subject has a second set of two alleles that are related to the two alleles of the subject, and second set of two alleles have a second gene of interest, wherein the second gene of interest is placed in a second construct b) introducing the second construct into a second test cell, evaluating the second test cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when second test cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein and wherein when the test cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non- functional protein or protein with decreased function. In some embodiments, the method further comprises obtaining a second genomic DNA from a second subject and identifying a second gene(s) of interest in at least two alleles from the genomic DNA, inserting at least one of the second gene(s) into a second construct, introducing the second construct into a second test cell, and mating the second cell with the first cell to produce a progeny cell. In some embodiments, the method further comprises evaluating the progeny cell for cell growth in a media, wherein the media lacks an amino acid, wherein the test cell growth is compared to a control cell that has the homologous gene, wherein when progeny cell growth is comparable to that of the control cell it indicates that the gene of interest encodes a functional protein, and wherein when the progeny cell growth is slow as compared to the control cell it indicates that the gene of interest encodes a non-functional protein or protein with decreased function and indicates the disease. Additional sequences [0250] PSAT1_codon_optimized integrating plasmid [0251] 1-1342= pUC19 vector backbone [0252] 1336-1343 and 4759-4764 (bolded)= SapI and SnaBI restriction sites used to liberate construct for integration [0253] 1343-1438 (italics)= sequence 5’ of SER1 start codon to direct integration [0254] 1439-2551 (underl PSAT1 open reading frame that has been codon optimized for expression in Saccharom yces cerevisiae. [0255] 2552-3014 (bolded italics)= Sequence 3’ of SER1 stop codon that includes SER1 terminator sequence [0256] 3015-4520 (lower case)= kanMX drug marker [0257] 4521-4761 (italics)= sequence 3’ of SER1 terminator to direct integration [0258] 4762-6097 (capital letters)= pUC19 vector backbone [0259] AB481 or pAS19-PSAT1-K sequence (SEQ ID NO: 3) GCACCAGTTATAA Examples [0260] The following examples are non-limiting and additional variants contemplated by one having ordinary skill in the art are encompassed within the scope of this disclosure. Example 1. Assays for determination of PSAT variant function [0261] As shown in Figure 2, the human protein coding sequence of the PSAT1 gene can functionally replace the corresponding SER1 gene in yeast. This single copy can be stably integrated into the genome under the control of the native yeast regulatory sequences for transcription, translation, and mRNA stability with the nucleic acid comprising the sequence as shown in Figure 2. This strategy can be applied to any metabolic enzyme, not just the serine pathway, by using the protein coding sequence for any metabolic enzyme in the construct in Fig.2. [0262] The PSAT1 sequence was codon optimized for expression in yeast (SEQ ID NO: 1: ATGGACGCGCCAAGACAGGTTGTGAATTTCGGACCTGGGCCAGCTAAATTGCCT

[0263] For frameshift mutations an optimized sequence was used up to the mutation. After the SNP, the human cDNA sequence, SEQ ID NO: 2, was used. (SEQ ID NO: 2:

[0264] In some embodiments, the PSAT1 is encoded by a gene comprising a sequence set forth in SEQ ID NO: 3. [0265] Cells were grown in liquid rich yeast medium (YPD) broth that contains serine. Cells expressing the wild type SER1 (yeast homolog of PSAT1), no gene, PSAT1, PSAT1 mutant A99V, PSAT1 mutant S179L, were used to inoculate (by replica pinning) prepared solid agar plates containing yeast minimal medium (SD), which lacks serine. Growth of each strain, which contains a PSAT1 variant or a control (e.g. the yeast SER1 gene or a ser1 deletion), was quantified by photographing the yeast growing on the solid agar plates and performing image analysis using custom software (written by the inventors). The assays include technical and biological replicates. As shown, the loss of function of the yeast enzymes produces a quantitative and easily measured trait, poor growth in the absence of serine supplementation. In the example below, it is shown that the human protein coding sequence of the PSAT1 gene can functionally replace the corresponding SER1 gene in yeast. This gives a yeast-based assay for measuring the activity of PSAT1 gene variants found in a specific patient, a genome-wide association study (GWAS), or the population at large. (Figure 3). As shown, is the growth in the absence of serine, for wildtype strain (“yeast gene”), a SER1 deletion (“no gene”) or strains with human PSAT1 coding sequence or two human disease gene variants (A99V and S179L, respectively). A t-test between “yeast gene” and “human gene” growth was not significant (N.S.) The growth conferred by variants 1 and 2 (disease alleles were significantly below that of the human gene (t-test p-values < 0.0001, ***). There was no significant difference between a gene deletion and variant 2, suggesting that variant 2 is equivalent to a complete loss of function. The tests on the yeast strains may be performed on either agar plates or in a liquid media. [0266] Assays were performed to assess the function of genes that were determined by computational methods to be either functional or non-functional (Figure 4). Tests were performed on PSAT proteins with the mutations: 1) K110Q, 2) V149M, 3) T156M, 4) R222*, 5) N236H 6) V250A. As shown in the table (Figure 4, right panel), PSAT proteins with the mutations K110Q and V149M were determined to be deleterious proteins. PSAT proteins with the mutations N236H and V250A were considered to be “neutral” while T156M and R222 were predicted to be deleterious or with an undetermined function, respectively. [0267] Assays for PSAT1 protein functions were performed on PSAT1 proteins with the mutations 1) K110Q, 2) V149M, 3) T156M, 4) R222, 5) N236H 6) V250A to determine protein function as compared to the predicted protein characteristics as determined by the computational methods (Figure 4, right panel). As shown in the left panel of Figure 4, the mutants K110Q, V149M, N236H and V250A were shown to have growth that was comparable to the growth of the wild type PSAT1 protein. The PSAT proteins with the mutations T156M and R222 were shown to be deleterious by this method. Thus the assay provides a fast diagnostic to show the functionality of a protein which cannot be predicted by a computational analysis. [0268] The assay can be used to perform tests on individual alleles as well. As shown in Figure 6, additional mutants were also tested for their performance in media that was lacking in serine. As shown, the PSAT mutants with a G78A and R213C mutation were compared to the growth of cells expressing PSAT1 (control), A99V, D100, and S179. These proteins were previously predicted to be variable unknowns. As shown is the growth data of the three known human disease gene variants (A99V, D100A and S179L), and suspected pathogenic variants that were classified as variable outcome strains (S179L and G78A). As shown, the S179L and G78A mutants have growth comparable to null alleles. [0269] Cell growth, may also be referred to as the “growth value”, and may be measured by optical density of a liquid culture. In some embodiments, cell growth, also the “growth value”, is measured by the area of a “patch” or “spot” of cells growing on solid media, the number of pixels of a “patch” or “spot” of cells growing on solid media, the intensity of the pixels in a “patch” or “spot” of cells growing on solid media, the change in any of these parameters over time, or a combination of any of the aforementioned parameters. Example 2: Assays for personalized yeast models for affected individuals and carriers [0270] Diploid strains carrying PSAT1/PSAT1, PSAT1/A99V and PSAT1/S179L were prepared. These diploid strains were prepared by mating haploid cells each containing one of the two variants, e.g. A99V and S179L. The resulting diploid cell is heterozygous for the two variants. Homozygous diploid strains and strains that are heterozygous for a wildtype and mutant version of the gene, e.g. PSAT1/A99V, are made in the same way. The yeast cells were then analyzed for growth in YPD media that lacked serine. This test may also be performed in agar plates or liquid media for assessment of cell growth. As shown in Figure 8, the diploid cells PSAT1/A99V and PSAT1/S179L were shown to function above the pathogenic threshold, which indicates that the protein is predicted to be functional, however the proteins have reduced activity as compared with the PSAT1/PSAT1 homozygous. The pathogenic threshold may be calculated for different heterozygotes. Crossing cells to generate a heterozygous A99V/S179L was performed to test the heterozygote for growth in media lacking serine. As shown in the graph, the heterozygous A99V/S179L produced a PSAT1 protein with decreased function which was predicted to lead to a pathogenic phenotype in a progeny carrying both the A99V and the S179L genes. As such, the data generated from the assays may be used to determine a threshold for disease and may be used to create personalized data prediction of disease, prediction of adult onset of a disease and prediction of disease of progeny for two subjects. An example of a personalized test is shown in Figure 7. As shown in Figure 7, is a test of diploid strains. The control is homozygous for PSAT1. The two parents are heterozygous for PSAT1/A99V and PSAT1/179L. As shown the progeny is a carrier of the A99V and the S179L mutation. The protein expressed by the progeny has decreased function as compared to the parent strains as well as the control cell. [0271] Cell growth, may also be referred to as the “growth value”, and may be measured by optical density of a liquid culture. In some embodiments, cell growth, also the “growth value”, is measured by the area of a “patch” or “spot” of cells growing on solid media, the number of pixels of a “patch” or “spot” of cells growing on solid media, the intensity of the pixels in a “patch” or “spot” of cells growing on solid media, the change in any of these parameters over time, or a combination of any of the aforementioned parameters. Example 3: Assessment of diploid yeast strains carrying PSAT mutations for personalized model systems [0272] As shown in Figure 9, the growth values of several haploids in the absence of serine for haploid strains containing the PSAT1 variants listed above each bar. The cells are grown in the methods previously described in which the media is lacking the essential amino acid, serine. From left to right is PSAT (control), A15V, A99V, c.delG107, D100A, D145Mfs*49, G78A, R213C, R342Dfs*6, S179L, S43R and S43R. N is the number of replicates. Y is the median growth value. NS or asterisks indicate the results of t-tests between a variant and PSAT1 (control). These are all alleles that have been associated with disease in the literature. A15V, A99V, c.delG107, D100A, D145Mfs*49 and S179L are considered in the literature as being pathogenic, G78A, R213C and S43R are annotated as variants of uncertain significance (VUS). As shown, the haploid cells carrying the mutant PSAT1 gene have a decreased function, with the significant lack of function is shown for mutants c.delG107, D145Mfs*49, G78A, R342Dfs*6 and S179L. [0273] Tests were then performed on diploid strains in order to examine the progeny cells that may carry at least one mutation in a diploid strain. As shown in Figures 10-18, the mutants as described in Figure 5, were used to examine the effects of having either one or two recessive genes that were shown to effect the growth of cells in a serine- free media. [0274] As shown in Figure 10, is a personalized yeast model for an affected patient and carrier parents (PSAT x D100A and c.delG107 x D100A). As shown in Figure 10, the progeny has two PSAT alleles (delG107 x D100A) that leads to a protein with decreased function. Thus a patient with this genotype, may need to be provided with a therapy that involves supplementation of the amino acid in order to have normal cellular functions. [0275] As shown in Figure 11, is a personalized yeast model for an affected patient with the carrier parents that both have the allele for a wild type PSAT1 gene and Arg342Aspfs gene. As shown, the progeny (3) has two PSAT alleles (Arg342Aspfsכ6 x Arg342Aspfsכ6) that leads to a protein with loss of function. Thus a patient with this genotype, may need to be provided with a therapy that involves supplementation of the amino acid in order to have normal cellular functions. As this test may be performed on individuals who are expecting, Determining a fetus with this genotype, one may need to provide with a therapy for a pregnant subject that involves supplementation of the amino acid in order to have normal cellular functions in a fetus. [0276] As shown in Figure 12, is a personalized yeast model for an affected patient with the carrier parents that both have the allele for A99V and the wild type PSAT1 gene. As shown, the progeny (3) has two PSAT1 alleles (A99V x A99V) that leads to a protein with decreased function. Thus a patient with this genotype, may need to be provided with a therapy that involves supplementation of the amino acid in order to have normal cellular functions. [0277] As shown in Figure 13, is a personalized yeast model for an affected patient with the carrier parents that both have the allele PSAT1 gene and gene for the PSAT1 with the S179L mutation. As shown in Figure 13, the progeny (3) has two PSAT1 alleles (S179L x S179L) that leads to a protein with complete loss of function. As this test may be performed on individuals who are expecting, Determining a fetus with this genotype, one may need to provide with a therapy for a pregnant subject that involves supplementation of the amino acid in order to have normal cellular functions in a fetus. This test may also be performed for genetic testing for a couple in order to determine their probability of having a child with a metabolic disease. [0278] As shown in Figure 14, is a personalized yeast model for an affected patient with the carrier parents that both are heterozygous for the wild type PSAT1 and a recessive PSAT1 mutant gene (PSAT1 x S179L and A99V x PSAT1). As shown, the progeny (4) has two PSAT alleles (A99V x S179L) that leads to a protein with decreased function. Thus a patient with this genotype, may need to be provided with a therapy that involves supplementation of the amino acid in order to have normal cellular functions. [0279] As shown in Figure 15, is a personalized yeast model for an affected patient with the carrier parents that both are heterozygous for the wild type PSAT1 and a recessive PSAT1 mutant gene. (both parents: S43R x PSAT1). As shown in Figure 15, the progeny (3) has two PSAT1 alleles (S43R x S43R) that leads to a protein that’s comparatively as functional as the parent. Thus assessment of the health of the patient will need to be evaluated to determine if serine supplementation is needed. [0280] A personalized yeast model was also performed for parents that have the alleles for PSAT1 with the G78A mutation and the wild type PSAT1. As shown in Figure 16, the progeny (3) has two PSAT1 alleles (G78A x G78A) that leads to a protein has a complete loss of function as compared to the parent and the wild type. [0281] A personalized yeast model was also performed for parents that have the alleles for PSAT1 with the R213C mutation and the wild type PSAT1. As shown in Figure 17, the progeny (3) has two PSAT1 alleles (R213C x R213C) that leads to a protein has decreased function as compared to the parent and the wild type. [0282] As shown in Figure 18, a personalized yeast model was also performed for two heterozygous parents that have the alleles for PSAT1 x A15V and D145Mfs*49 x PSAT100. The progeny (4) has two PSAT alleles (D145Mfs*49 x A15V) that lead to a protein with decreased function as compared to the wild type. However, the progeny does have similar protein characteristics with one of the parents (Bar 3), this may possibly show that one mutant is dominant over the other. [0283] In view of the personalized tests, it is envisioned that one would be enabled to predict the types of alleles a child would receive from their parents as well as the outcomes for each case. For example, one would be able to predict if a certain mutation was dominant over another (such as the example shown in Figure 18), which could possibly lead to a protein that has more function than a child with two recessive alleles (as shown in Figures 16 and 17). Thus a model can be created for prospective parents that would let one know the probability of having a child that had both PSAT1 wild type genes as well, two recessive mutant genes, and possible outcomes of the heterozygotes. Thus one would have the ability to develop a therapeutic or prepare an early intervention such as a dietary plan with supplements to prevent neonatal problems or prevent adult onset of a disease. Example 4 - Yeast model for arginine biosynthesis pathway [0284] The yeast enzymes in three colinear steps of the arginine biosynthesis pathway are highly conserved with their human orthologs (Table 1). In humans, this pathway is known as the urea cycle because it is the principal mechanism for the clearance of waste nitrogen resulting from protein turnover and enzyme deficiencies cause urea cycle disorders [1, 2]. [0285] In order to test whether yeast models could be established for the human urea cycle pathway, the corresponding yeast orthologs of OTC, ASS1, and ASL were replaced with the wildtype human ORF or a variant containing a published early onset disease allele (otc-R141Q [3], ass1-R127W [4], asl-Q286R [5]). Functional assays were performed on sequence confirmed biological replicates as described for PSAT1 (Figure 1), except with minimal medium lacking arginine as the condition-specific growth assay. Previous studies had successfully introduced OTC [6] and ASL [5] into yeast, although both were overexpressed from high copy plasmids and a strong galactose-inducible promoter. In this experiment (Figure 19), the human protein coding sequences conferred condition-specific growth at 82% (OTC), 87% (ASS1), and 93% (ASL) of the growth conferred by their respective yeast orthologs, and the disease alleles showed statistically significant growth defects (Student’s t-test, p<0.001). The custom codon optimization method described herein in Example 5 (based on codon usage frequency) substantially improved the degree to which OTC and ASS1 were able to complement loss of their yeast orthologs. The human ASS1 cDNA sequence only conferred growth at 49% of that of the yeast ortholog, and for OTC, our codon optimization method resulted in better complementation than codon optimization by IDT (82% versus 54%). Example 5 - Codon harmonization method [0286] Figure 20 show an embodiment of a Codon harmonization method described herein. Human cDNA and yeast cDNA sequences (both products of nature) for two orthologous genes were aligned. There will often be regions (gap, gray) where there is additional sequence (resulting in extra amino acids) in one of the two sequences. Positions where both cDNAs encode the same amino acid were identified (*) and the codons in the human cDNA were replaced with the yeast codon used at that position in the alignment (yellow bars), if the human and yeast codons were different. For the remaining amino acids positions that align between the two sequences (e.g., not in gaps), it was checked whether the frequency of codon in humans is comparable to the frequency of that codon in yeast. If codon usage frequencies were not the same between the two species, the codon in the human cDNA was changed to a codon (for the same amino acid) that is closer to the yeast frequency (green). Example 6 [0287] Reverse harmonization for codon optimization is performed by obtaining a sequence of a first gene/cDNA to be optimized from a first organism; obtaining a sequence of a second gene/cDNA from a second organism, wherein the second gene/cDNA is an ortholog of the first gene/cDNA, and the first gene/cDNA is to be optimized for expression in the second organism; performing a first alignment of the first and second gene/cDNA sequences; obtaining a protein sequence encoded by the a first gene/cDNA; obtaining a protein sequence encoded by the second gene/cDNA; performing a second alignment of the protein sequences encoded by the firs tan d second gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in the first and second gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in the first gene/cDNA with the codon in the second gene/cDNA, if the codons in the first and second gene/cDNA that encode the same amino acid at mutually corresponding positions in the second alignment are different between the first and second gene/cDNA, thereby obtaining a codon optimized first gene/cDNA from the first organism. Positions in the first alignment are identified where codons differ between the first and the second genes/DNA; and replaced with codons in the first gene/cDNA lacking corresponding codons in the second gene/cDNA by selecting codons from the second organism that encode the same amino acid. Codon from the second organism are selected based on a frequency of usage of a codon encoding a particular amino acid in the second organism. Following codon optimization by reverse harmonization, a protein encoded by the codon optimized first gene/cDNA is expressed more efficiently and/or at a higher level in the second organism as compared to a codon non-optimized first gene/cDNA. Example 7 [0288] Reverse harmonization for codon optimization is performed by obtaining a sequence of a human gene/cDNA to be optimized from a human; obtaining a sequence of a yeast gene/cDNA from a yeast, wherein the yeast gene/cDNA is an ortholog of the human gene/cDNA, and the human gene/cDNA is to be optimized for expression in the yeast; performing a first alignment of the human and yeast gene/cDNA sequences; obtaining a protein sequence encoded by the human gene/cDNA; obtaining a protein sequence encoded by the yeast gene/cDNA; performing a second alignment of the protein sequences encoded by the human and yeast gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in the human and yeast gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in the human gene/cDNA with the codon in the yeast gene/cDNA, if the codons in the human and yeast gene/cDNA that encode the same amino acid at mutually corresponding positions in the second alignment are different between the human ad yeast gene/cDNA, thereby obtaining a codon optimized human gene/cDNA. Positions in the first alignment are identified where codons in the human gene/cDNA lack corresponding codons in the yeast gene/cDNA sequences; and replaced with codons in the human gene/cDNA lacking corresponding codons in the yeast gene/cDNA by selecting codons from the yeast that encode the same amino acid. Codon from the yeast are selected based on a frequency of usage of a codon encoding a particular amino acid in the yeast. Following codon optimization by reverse harmonization, a protein encoded by the codon optimized human gene/cDNA is expressed more efficiently and at a higher level in the yeast as compared to a codon non-optimized human gene/cDNA. Example 8 [0289] Reverse harmonization for codon optimization is performed by obtaining a sequence of one or more of the sequences shown in Table 2 (Gene X) to be optimized; obtaining a sequence of a vegetable gene/cDNA from a vegetable, wherein the vegetable gene/cDNA is an ortholog of Gene X, and Gene X is to be optimized for expression in the vegetable; performing a first alignment of Gene X and the vegetable gene/cDNA sequences; obtaining a protein sequence encoded by Gene X; obtaining a protein sequence encoded by the vegetable gene/cDNA; performing a second alignment of the protein sequences encoded by Gene X and the vegetable gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in Gene X and vegetable gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in Gene X with the codon in the vegetable gene/cDNA, if the codons in Gene X and vegetable gene/cDNA that encode the same amino acid at mutually corresponding positions in the second alignment are different between Gene X and the vegetable gene/cDNA, thereby obtaining a codon optimized Gene X. Positions in the first alignment are identified where codons in Gene X lack corresponding codons in the vegetable gene/cDNA sequences; and replaced with codons in Gene X lacking corresponding codons in the vegetable gene/cDNA by selecting codons from the vegetable that encode the same amino acid. Codon from the vegetable are selected based on a frequency of usage of a codon encoding a particular amino acid in the vegetable. Following codon optimization by reverse harmonization, a protein encoded by the codon optimized Gene X is expressed more efficiently and at a higher level in the vegetable as compared to a codon non-optimized Gene X. Example 9 [0290] Reverse harmonization for codon optimization is performed by obtaining a sequence of one or more of the sequences shown in Table 2 (Gene Y) to be optimized; obtaining a sequence of a pet gene/cDNA from a pet (e.g., cat, dog, hamster, and the like), wherein the pet gene/cDNA is an ortholog of Gene Y, and Gene Y is to be optimized for expression in the pet; performing a first alignment of Gene Y and the pet gene/cDNA sequences; obtaining a protein sequence encoded by Gene Y; obtaining a protein sequence encoded by the pet gene/cDNA; performing a second alignment of the protein sequences encoded by Gene Y and the pet gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in Gene Y and pet gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in Gene Y with the codon in the pet gene/cDNA, if the codons in Gene Y and pet gene/cDNA that encode the same amino acid at mutually corresponding positions in the second alignment are different between Gene Y and the pet gene/cDNA, thereby obtaining a codon optimized Gene Y. Positions in the first alignment are identified where codons in Gene Y lack corresponding codons in the pet gene/cDNA sequences; and replaced with codons in Gene Y lacking corresponding codons in the pet gene/cDNA by selecting codons from the pet that encode the same amino acid. Codon from the pet are selected based on a frequency of usage of a codon encoding a particular amino acid in the pet. Following codon optimization by reverse harmonization, a protein encoded by the codon optimized Gene Y is expressed more efficiently and at a higher level in the pet as compared to a codon non-optimized Gene Y. Example 10 [0291] Reverse harmonization for codon optimization is performed by obtaining a sequence of one or more of the sequences shown in Table 2 (Gene Z) to be optimized; obtaining a sequence of a yeast gene/cDNA from a yeast, wherein the yeast gene/cDNA is an ortholog of Gene Z, and Gene Z is to be optimized for expression in the yeast; performing a first alignment of Gene Z and the yeast gene/cDNA sequences; obtaining a protein sequence encoded by Gene Z; obtaining a protein sequence encoded by the yeast gene/cDNA; performing a second alignment of the protein sequences encoded by Gene Z and the yeast gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in Gene Z and yeast gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in Gene Z with the codon in the yeast gene/cDNA, if the codons in Gene Z and yeast gene/cDNA that encode the same amino acid at mutually corresponding positions in the second alignment are different between Gene Z and the yeast gene/cDNA, thereby obtaining a codon optimized Gene Z. Positions in the first alignment are identified where codons in Gene Z lack corresponding codons in the yeast gene/cDNA sequences; and replaced with codons in Gene Z lacking corresponding codons in the yeast gene/cDNA by selecting codons from the yeast that encode the same amino acid. Codon from the yeast are selected based on a frequency of usage of a codon encoding a particular amino acid in the yeast. Following codon optimization by reverse harmonization, a protein encoded by the codon optimized Gene Z is expressed more efficiently and at a higher level in the yeast as compared to a codon non-optimized Gene Z. Example 11 [0292] Reverse harmonization for codon optimization is performed by obtaining a sequence of one or more of the sequences shown in Table 2 (Gene A encoding an enzyme for ethanol production) to be optimized; obtaining a sequence of a bacterial gene/cDNA from a bacteria, wherein the bacterial gene/cDNA is an ortholog of Gene A, and Gene A is to be optimized for expression in the bacteria; performing a first alignment of Gene A and the bacteria gene/cDNA sequences; obtaining a protein sequence encoded by Gene A; obtaining a protein sequence encoded by the bacteria gene/cDNA; performing a second alignment of the protein sequences encoded by Gene A and the bacteria gene/cDNA; identifying positions in the first alignment where codons that mutually correspond to each other in Gene A and bacteria gene/cDNA sequences encode the same amino acid at mutually corresponding positions in the second alignment; and replacing the codon in Gene A with the codon in the bacteria gene/cDNA, if the codons in Gene A and bacteria gene/cDNA that encode the same amino acid at mutually corresponding positions in the second alignment are different between Gene A and the bacteria gene/cDNA, thereby obtaining a codon optimized Gene A. Positions in the first alignment are identified where codons in Gene A lack corresponding codons in the bacteria gene/cDNA sequences; and replaced with codons in Gene A lacking corresponding codons in the bacteria gene/cDNA by selecting codons from the bacteria that encode the same amino acid. Codon from the bacteria are selected based on a frequency of usage of a codon encoding a particular amino acid in the bacteria. Following codon optimization by reverse harmonization, a protein encoded by the codon optimized Gene A is expressed more efficiently and at a higher level in the bacteria as compared to a codon non- optimized Gene A. [0293] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” [0294] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. [0295] Any of the features of an embodiment of the first through eleventh aspects is applicable to all aspects and embodiments identified herein. Moreover, any of the features of an embodiment of the first through eleventh aspects is independently combinable, partly or wholly with other embodiments described herein in any way, e.g., one, two, or three or more embodiments may be combinable in whole or in part. Further, any of the features of an embodiment of the first through eleventh aspects may be made optional to other aspects or embodiments. References: [0296] 1. Helman, G., I. Pacheco-Colon, and A.L. Gropman, The urea cycle disorders. Semin Neurol, 2014.34(3): p.341-9. [0297] 2. Mew, N.A., et al., Urea Cycle Disorders Overview, in Gene Reviews, M.P. Adam, et al., Editors. 2003 Apr 29 [Updated 2017 Jun 22], University of Washington: Seattle, Washington. [0298] 3. McCullough, B.A., et al., Genotype spectrum of ornithine transcarbamylase deficiency: correlation with the clinical and biochemical phenotype. Am J Med Genet, 2000.93(4): p.313-9. [0299] 4. Diez-Fernandez, C., et al., Kinetic mutations in argininosuccinate synthetase deficiency: characterisation and in vitro correction by substrate supplementation. J Med Genet, 2016.53(10): p.710-9. [0300] 5. Trevisson, E., et al., Functional complementation in yeast allows molecular characterization of missense argininosuccinate lyase mutations. J Biol Chem, 2009.284(42): p.28926-34. [0301] 6. Cheng, M.Y., et al., Import and processing of human ornithine transcarbamoylase precursor by mitochondria from Saccharomyces cerevisiae. Proc Natl Acad Sci U S A, 1987.84(12): p.4063-7. [0302] 7. Gamble, C.E., et al., Adjacent Codons Act in Concert to Modulate Translation Efficiency in Yeast. Cell, 2016.166(3): p.679-690. [0303] Richards, S., Aziz, N., Bale, S., Bick, D., Das, S., Gastier-Foster, J., Grody, W.W., Hegde, M., Lyon, E., Spector, E., et al. (2015). Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genetics in medicine : official journal of the American College of Medical Genetics 17, 405- 424.