Albinism in the domestic cat (Felis catus) is associated with a tyrosinase (TYR) mutation

Possibilities of skin coat color-dependent risks and risk factors of squamous cell carcinoma and deafness of domestic cats inferred via RNA-seq data

The transcriptome data of skin cells from domestic cats with brown, orange, and white coats were analyzed using a public database to investigate the possible relationship between coat color-related gene expression and squamous cell carcinoma risk, as well as the mechanism of deafness in white cats. We found that the ratio of the expression level of genes suppressing squamous cell carcinoma to that of genes promoting squamous cell carcinoma might be considerably lower than the theoretical estimation in skin cells with orange and white coats in white-spotted cat. We also found the possibility of the frequent production of KIT lacking the first exon (d1KIT) in skin cells with white coats, and d1KIT production exhibited a substantial negative correlation with the expression of SOX10, which is essential for melanocyte formation and adjustment of hearing function. Additionally, the production of d1KIT was expected to be due to the insulating activity of the feline endogenous retrovirus 1 (FERV1) LTR in the first intron of KIT by its CTCF binding sequence repeat. These results contribute to basic veterinary research to understand the relationship between cat skin coat and disease risk, as well as the underlying mechanism.

Chromosome-level reference genome for North American bison (Bison bison) and variant database aids in identifying albino mutation

We developed a highly contiguous chromosome-level reference genome for North American bison to provide a platform to evaluate the conservation, ecological, evolutionary, and population genomics of this species. Generated from a F1 hybrid between a North American bison dam and a domestic cattle bull, completeness and contiguity exceed that of other published bison genome assemblies. To demonstrate the utility for genome-wide variant frequency estimation, we compiled a genomic variant database consisting of 3 true albino bison and 44 wild-type pelage color bison. Through the examination of genomic variants fixed in the albino cohort and absent in the controls, we identified a nonsynonymous single nucleotide polymorphism (SNP) mutation on chromosome 29 in exon 3 of the tyrosinase gene (c.1114C>T). A TaqMan SNP Genotyping Assay was developed to genotype this SNP in a total of 283 animals across 29 herds. This assay confirmed the absence of homozygous variants in all animals except 7 true albino bison included in this study. In addition, the only heterozygous animals identified were 2 wild-type pelage color dams of albino offspring. Therefore, we propose that this new high-quality bison genome assembly and incipient variant database provides a highly robust and informative resource for genomics investigations for this iconic North American species.

Analysis of the genetic loci of pigment pattern evolution in vertebrates

Vertebrate pigmentation patterns are amongst the best characterised model systems for studying the genetic basis of adaptive evolution. The wealth of available data on the genetic basis for pigmentation evolution allows for analysis of trends and quantitative testing of evolutionary hypotheses. We employed Gephebase, a database of genetic variants associated with natural and domesticated trait variation, to examine trends in how cis-regulatory and coding mutations contribute to vertebrate pigmentation phenotypes, as well as factors that favour one mutation type over the other. We found that studies with lower ascertainment bias identified higher proportions of cis-regulatory mutations, and that cis-regulatory mutations were more common amongst animals harbouring a higher number of pigment cell classes. We classified pigmentation traits firstly according to their physiological basis and secondly according to whether they affect colour or pattern, and identified that carotenoid-based pigmentation and variation in pattern boundaries are preferentially associated with cis-regulatory change. We also classified genes according to their developmental, cellular, and molecular functions. We found a greater proportion of cis-regulatory mutations in genes implicated in upstream developmental processes compared to those involved in downstream cellular functions, and that ligands were associated with a higher proportion of cis-regulatory mutations than their respective receptors. Based on these trends, we discuss future directions for research in vertebrate pigmentation evolution.

A genome-wide scan to identify signatures of selection in Lueyang black -bone chicken

Lueyang black-bone chicken is a domestic breed in China. The genetic mechanism of the formation of important economic traits of this breed has not been studied systematically. Therefore, in this study, whole genome resequencing was used to systematically analyze and evaluate the genetic diversity of the black-feather and white-feather populations, and to screen and identify key genes related to phenotypes. The results of principal component analysis and population structure analysis showed that Lueyang black-feathered chickens and white-feathered chickens could be divided into 2 subgroups, and the genetic diversity of black-feathered chicken was richer than that of white-feathered chickens. Linkage disequilibrium analysis also showed that the selection intensity of black-feathered chickens was lower than for white-feathered chickens, which was mainly due to the small population size of white-feathered chickens and a certain degree of inbreeding. Fixation index (F_ST) analysis revealed that the candidate genes related to feather color traits were G-gamma, FA, FERM, Kelch, TGFb, Arf, FERM, and melanin synthesis-related gene tyrosinase (TYR). Based on Kyoto Encyclopedia of Genes and Genomes enrichment analysis, Jak-STAT, mTOR, and TGF-β signaling pathways were mainly related to melanogenesis and plume color. The findings of this study supported important information for the evaluation and protection of chicken genetic resources and help to analyze the unique genetic phenotypes such as melanin deposition and feather color of Lueyang black-bone chicken. Additionally, it could provide basic research data for the improvement and breeding of Lueyang black-bone chicken with characteristic traits.

The Mechanisms of Fur Development and Color Formation in American Mink Revealed Using Comparative Transcriptomics

American mink fur is an important economic product, but the molecular mechanisms underlying its color formation and fur development remain unclear. We used RNA-seq to analyze the skin transcriptomes of young and adult mink with two different hair colors. The mink comprised black adults (AB), white adults (AW), black juveniles (TB), and white juveniles (TW) (three each). Through pair comparison and cross-screening among different subgroups, we found that 13 KRTAP genes and five signaling pathways (the JAK-STAT signaling pathway (cfa04630), signaling pathways regulating pluripotency of stem cells (cfa04550), ECM-receptor interaction (cfa04512), focal adhesion (cfa04510), and the Ras signaling pathway (cfa04014)) were related to mink fur development. We also found that members of a tyrosinase family (TYR, TYRP1, and TYRP2) are involved in mink hair color formation. The expression levels of TYR were higher in young black mink than in young white mink, but this phenomenon was not observed in adult mink. Our study found significant differences in adult and juvenile mink skin transcriptomes, which may shed light on the mechanisms of mink fur development. At the same time, the skin transcriptomes of black and white mink also showed differences, with the results varying by age, suggesting that the genes regulating hair color are active in early development rather than in adulthood. The results of this study provide molecular support in breeding for mink coat color and improving fur quality.

A community-science approach identifies genetic variants associated with three color morphs in ball pythons (Python regius)

Color morphs in ball pythons (Python regius) provide a unique and largely untapped resource for understanding the genetics of coloration in reptiles. Here we use a community-science approach to investigate the genetics of three color morphs affecting production of the pigment melanin. These morphs-Albino, Lavender Albino, and Ultramel-show a loss of melanin in the skin and eyes, ranging from severe (Albino) to moderate (Lavender Albino) to mild (Ultramel). To identify genetic variants causing each morph, we recruited shed skins of pet ball pythons via social media, extracted DNA from the skins, and searched for putative loss-of-function variants in homologs of genes controlling melanin production in other vertebrates. We report that the Albino morph is associated with missense and non-coding variants in the gene TYR. The Lavender Albino morph is associated with a deletion in the gene OCA2. The Ultramel morph is associated with a missense variant and a putative deletion in the gene TYRP1. Our study is one of the first to identify genetic variants associated with color morphs in ball pythons and shows that pet samples recruited from the community can provide a resource for genetic studies in this species.

PMEL p.Leu18del dilutes coat color of Kumamoto sub-breed of Japanese Brown cattle

Background

Coat color is important for registration and maintenance of livestock. Standard coat color of Kumamoto sub-breed of Japanese Brown cattle is solid brown, but individuals with diluted coat color have been observed recently. In this study, we attempted to identify polymorphism(s) responsible for coat color dilution by whole genome analysis.

Results

One of the diluted cattle possessed 7302 exonic polymorphisms which could affect genes’ function. Among them, 14 polymorphisms in 10 coat color-related genes were assumed to be specific for the diluted cattle. Subsequent genotyping with three diluted cattle and 74 standard cattle elucidated that PMEL p.Leu18del was the causative polymorphism for coat color dilution in this sub-breed. Individuals with del/del type of this polymorphism showed diluted coat color, but coat color of heterozygotes were intermediate with various dilution rates.

Conclusions

Coat color dilution of Kumamoto sub-breed was caused by PMEL p.Leu18del. The causative del allele has been detected in several genetically distant cattle breeds, suggesting that PMEL p.Leu18del can be used as a DNA marker to control cattle coat color.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08916-8.

Genetic epidemiology of blood type, disease and trait variants, and genome-wide genetic diversity in over 11,000 domestic cats

In the largest DNA-based study of domestic cats to date, 11,036 individuals (10,419 pedigreed cats and 617 non-pedigreed cats) were genotyped via commercial panel testing elucidating the distribution and frequency of known disease, blood type, and physical trait associated genetic variants across cat breeds. This study provides allele frequencies for many disease-associated variants for the first time and provides updates on previously reported information with evidence suggesting that DNA testing has been effectively used to reduce disease associated variants within certain pedigreed cat populations over time. We identified 13 disease-associated variants in 47 breeds or breed types in which the variant had not previously been documented, highlighting the relevance of comprehensive genetic screening across breeds. Three disease-associated variants were discovered in non-pedigreed cats only. To investigate the causality of nine disease-associated variants in cats of different breed backgrounds our veterinarians conducted owner interviews, reviewed clinical records, and invited cats to have follow-up clinical examinations. Additionally, genetic variants determining blood types A, B and AB, which are relevant clinically and in cat breeding, were genotyped. Appearance-associated genetic variation in all cats is also discussed. Lastly, genome-wide SNP heterozygosity levels were calculated to obtain a comparable measure of the genetic diversity in different cat breeds. This study represents the first comprehensive exploration of informative Mendelian variants in felines by screening over 10,000 pedigreed cats. The results qualitatively contribute to the understanding of feline variant heritage and genetic diversity and demonstrate the clinical utility and importance of such information in supporting breeding programs and the research community. The work also highlights the crucial commitment of pedigreed cat breeders and registries in supporting the establishment of large genomic databases, that when combined with phenotype information can advance scientific understanding and provide insights that can be applied to improve the health and welfare of cats.

Domestic cats are one of the world’s most popular companion animals, of which pedigreed cats represent small unique subpopulations. Genetic research on pedigreed cats has facilitated discoveries of heritable conditions resulting in the availability of DNA testing for studying and managing inherited disorders and traits in specific cat breeds. We have explored an extensive study cohort of 11,036 domestic cat samples representing pedigreed cats of 90 breeds and breed types. This work provided insight into the heritage of feline disease and trait alleles. We gained knowledge on the most common and relevant genetic markers for inherited disorders and physical traits, and the genetic determinants of the clinically relevant AB blood group system. We also used a measure of genetic diversity to compare inbreeding levels within and between breeds. This information can help support sustainable breeding goals within the cat fancy. Direct-to-consumer genetic tests help to raise awareness of various inherited single gene conditions in cats and provide information that owners can share with their veterinarians. In due course, ventures of this type will enable the genetics of common complex feline disease to be deciphered, paving the way for precision healthcare with the potential to ultimately improve welfare for all cats.

Recognition of Coat Pattern Variation and Broken Tail Phenomenon in the Asiatic Golden Cat (Catopuma temminckii)

Simple Summary

A variety of new survey technologies are continuously being developed and used in wildlife monitoring. Rapidly advancing and widely used camera trap survey technology has helped to capture data and gain insights into many species. The Eastern Himalayas is a global biodiversity hotspot with exceptionally high species diversity. The Asian golden cat is widely distributed in the Yarlung Zangbo Grand Canyon National Nature Reserve. It inhabits seasonal rain forests from 100 m above sea level to the Rhododendron forest up to 3500 m above sea level. Coat pattern variation in the Asian golden cat is particularly prominent in this region. The common color type is the most widely distributed, followed by nine other types. We found 10 coat pattern variations and two coat patterns with a broken tail made up 0.32% of independent photos taken during a long-term nine-year monitoring program. The variation in coat patterns is indicative of the geography of the region. Environmental conditions regulate and activate the genetic diversity of Asian golden cat phenotypes. This study further strengthened the understanding of the basic knowledge of golden cat color types and lays the foundation for exploring the diversity of golden cat color types at the molecular level.

Abstract

The Asian golden cat (Catopuma temminckii) is the most varied wild cat species in terms of coat color. Understanding coat pattern variation will help to elucidate the mechanisms behind it as well as its relationship with the environment. We conducted long-term (2013–2021) monitoring of Asian golden cats in the Yarlung Zangbo Grand Canyon National Nature Reserve, Tibet, using camera traps at 283 points over 89,991 camera days. A total of 620 cat photos were recorded, including 344 (55.48%) with recognizable color patterns. Vector graphics of the coat patterns were extracted from the field image data, which revealed 10 color types in the ratio common: cinnamon: reddish-brown long hair: ocelot: blackening: melanistic: gray: brown: brown short hair: pure black = 123:76:57:35:22:8:7:7:5:4. The genes for coat pattern variation are widespread in the Asian golden cat population and are relatively stable. The increase in population size intraspecific competition has led to the tail break phenotype in individual cats. The gene encoding for tail breakage in Asian golden cats remains unknown. This study provides basic information for understanding faunal diversity in the Eastern Himalayan biodiversity hotspot and serves as a reference for studies on the formation mechanisms for feline color pattern diversity.

Canine coat pigmentation genetics: a review

Our understanding of canine coat colour genetics and the associated health implications is developing rapidly. To date, there are 15 genes with known roles in canine coat colour phenotypes. Many coat phenotypes result from complex and/or epistatic genetic interactions among variants within and between loci, some of which remain unidentified. Some genes involved in canine pigmentation have been linked to aural, visual and neurological impairments. Consequently, coat pigmentation in the domestic dog retains considerable ethical and economic interest. In this paper we discuss coat colour phenotypes in the domestic dog, the genes and variants responsible for these phenotypes and any proven coat colour-associated health effects.

Five genetic variants explain over 70% of hair coat pheomelanin intensity variation in purebred and mixed breed domestic dogs

In mammals, the pigment molecule pheomelanin confers red and yellow color to hair, and the intensity of this coloration is caused by variation in the amount of pheomelanin. Domestic dogs exhibit a wide range of pheomelanin intensity, ranging from the white coat of the Samoyed to the deep red coat of the Irish Setter. While several genetic variants have been associated with specific coat intensity phenotypes in certain dog breeds, they do not explain the majority of phenotypic variation across breeds. In order to gain further insight into the extent of multigenicity and epistatic interactions underlying coat pheomelanin intensity in dogs, we leveraged a large dataset obtained via a direct-to-consumer canine genetic testing service. This consisted of genome-wide single nucleotide polymorphism (SNP) genotype data and owner-provided photos for 3,057 pheomelanic mixed breed and purebred dogs from 63 breeds and varieties spanning the full range of canine coat pheomelanin intensity. We first performed a genome-wide association study (GWAS) on 2,149 of these dogs to search for additional genetic variants that underlie intensity variation. GWAS identified five loci significantly associated with intensity, of which two (CFA15 29.8 Mb and CFA20 55.8 Mb) replicate previous findings and three (CFA2 74.7 Mb, CFA18 12.9 Mb, CFA21 10.9 Mb) have not previously been reported. In order to assess the combined predictive power of these loci across dog breeds, we used our GWAS data set to fit a linear model, which explained over 70% of variation in coat pheomelanin intensity in an independent validation dataset of 908 dogs. These results introduce three novel pheomelanin intensity loci, and further demonstrate the multigenic nature of coat pheomelanin intensity determination in domestic dogs.

A domestic cat whole exome sequencing resource for trait discovery

Over 94 million domestic cats are susceptible to cancers and other common and rare diseases. Whole exome sequencing (WES) is a proven strategy to study these disease-causing variants. Presented is a 35.7 Mb exome capture design based on the annotated Felis_catus_9.0 genome assembly, covering 201,683 regions of the cat genome. Whole exome sequencing was conducted on 41 cats with known and unknown genetic diseases and traits, of which ten cats had matching whole genome sequence (WGS) data available, used to validate WES performance. At 80 × mean exome depth of coverage, 96.4% of on-target base coverage had a sequencing depth > 20-fold, while over 98% of single nucleotide variants (SNVs) identified by WGS were also identified by WES. Platform-specific SNVs were restricted to sex chromosomes and a small number of olfactory receptor genes. Within the 41 cats, we identified 31 previously known causal variants and discovered new gene candidate variants, including novel missense variance for polycystic kidney disease and atrichia in the Peterbald cat. These results show the utility of WES to identify novel gene candidate alleles for diseases and traits for the first time in a feline model.

Patterns of allele frequency differences among domestic cat breeds assessed by a 63K SNP array

Cats are ubiquitous companion animals that have been keenly associated with humans for thousands of years and only recently have been intentionally bred for aesthetically appealing coat looks and body forms. The intense selection on single gene phenotypes and the various breeding histories of cat breeds have left different marks on the genomes. Using a previously published 63K Feline SNP array dataset of twenty-six cat breeds, this study utilized a genetic differentiation-based method (di) to empirically identify candidate regions under selection. Defined as three or more overlapping (500Kb) windows of high levels of population differentiation, we identified a total of 205 candidate regions under selection across cat breeds with an average of 6 candidate regions per breed and an average size of 1.5 Mb per candidate region. Using the combined size of candidate regions of each breed, we conservatively estimate that a minimum of ~ 0.1-0.7% of the autosomal genome is potentially under selection in cats. As positive controls and tests of our methodology, we explored the candidate regions of known breed-defining genes (e.g., FGF5 for longhaired breeds) and we were able to detect the genes within candidate regions, each in its corresponding breed. For breed specific exploration of candidate regions under selection, eleven representative candidate regions were found to encompass potential candidate genes for several phenotypes such as brachycephaly of Persian (DLX6, DLX5, DLX2), curled ears of American Curl (MCRIP2, PBX1), and body-form of Siamese and Oriental (ADGRD1), which encourages further molecular investigations. The current assessment of the candidate regions under selection is empiric and detailed analyses are needed to rigorously disentangle effects of demography and population structure from artificial selection.

A genetic typing method for albino mutation in the Mongolian gerbil by PCR-RFLP analysis

1. We established a PCR-RFLP analysis targeting R77H mutation in the Tyr gene as a more effective genotyping to identify carrier (C/c) with the albino allele and the agouti phenotypes. 2. Our breeding system, which targets the R77H site, is a useful cue for detecting C/c carriers with the agouti-phenotype and helps us to obtain albinos by mating agouti-phenotype carriers.

Pigmentation formation and expression analysis of tyrosinase in Siniperca chuatsi

Animal pigmentation primarily depends on the presence and mixing ratio of chromatophores, functioning in animal survival and communication. For the benthic and carnivorous Siniperca chuatsi, pigmentation pattern is key to concealment and predation. In this study, the formation, distribution, and main pattern of chromatophores were observed in the embryos, larvae, skins, and visceral tissues from S. chuatsi. Melanophores were firstly visualized in the yolk sac at segmentation stage, and then they were migrated to the whole body and further clustered into the black stripes, bands, and patches. In adult S. chuatsi, the head, black band, and body side skins mainly contained melanophores, showing as deep or light black. The abdomen skin mainly contained iridophores, showing as silvery. In the eye, the pigment layers were located in the epithelial layers of iris and retina and shown as black. Then, the pigmentation-related gene, tyrosinase gene from S. chuatsi (Sc-tyr) was analyzed by bioinformatics and quantitative methods. The Sc-tyr gene encoded a protein with 540 amino acids (Sc-TYR). The Sc-TYR contained two copper ion binding sites, which were coordinated by six conserved histidines (H182, H205, H214, H366, H370, H393) and necessary for catalytic activity. The Sc-TYR was well conserved compared with TYR of various species with higher degree of sequence similarity with other fishes (77.6-98.3%). The qRT-PCR test showed that the Sc-tyr mRNA reached the peak value at segmentation stage in the embryo development, the black skins displayed a higher expression level than that in silvery skin, and the eye had the highest expression level compared with other tissues. Further research on enzyme activity showed that the expression patterns of tyrosinase activity were similar to that of the Sc-tyr mRNA. Comparing with the results of molecular and phenotype, it was found that the temporal and spatial distributions of tyrosinase corresponded well with changes in pigmentation patterns and the intensity of skin melanization. This study initially explored the pigmentation formation and tyrosinase expression, which served as a foundation for further insight into the genetics mechanism of body color formation in S. chuatsi.

Werewolf, There Wolf: Variants in Hairless Associated with Hypotrichia and Roaning in the Lykoi Cat Breed

A variety of cat breeds have been developed via novelty selection on aesthetic, dermatological traits, such as coat colors and fur types. A recently developed breed, the lykoi (a.k.a. werewolf cat), was bred from cats with a sparse hair coat with roaning, implying full color and all white hairs. The lykoi phenotype is a form of hypotrichia, presenting as a significant reduction in the average numbers of follicles per hair follicle group as compared to domestic shorthair cats, a mild to severe perifollicular to mural lymphocytic infiltration in 77% of observed hair follicle groups, and the follicles are often miniaturized, dilated, and dysplastic. Whole genome sequencing was conducted on a single lykoi cat that was a cross between two independently ascertained lineages. Comparison to the 99 Lives dataset of 194 non-lykoi cats suggested two variants in the cat homolog for Hairless (HR) (HR lysine demethylase and nuclear receptor corepressor) as candidate causal gene variants. The lykoi cat was a compound heterozygote for two loss of function variants in HR, an exon 3 c.1255_1256dupGT (chrB1:36040783), which should produce a stop codon at amino acid 420 (p.Gln420Serfs*100) and, an exon 18 c.3389insGACA (chrB1:36051555), which should produce a stop codon at amino acid position 1130 (p.Ser1130Argfs*29). Ascertainment of 14 additional cats from founder lineages from Canada, France and different areas of the USA identified four additional loss of function HR variants likely causing the highly similar phenotypic hair coat across the diverse cats. The novel variants in HR for cat hypotrichia can now be established between minor differences in the phenotypic presentations.

Donskoy cats as a new model of oculocutaneous albinism with the identification of a splice-site variant in Hermansky-Pudlak Syndrome 5 gene

In the feline Donskoy breed, a phenotype that breeders call "pink-eye," with associated light-brown skin, yellow irises and red-eye effect, has been described. Genealogical data indicated an autosomal recessive inheritance pattern. A single candidate region was identified by genome-wide association study and SNP-based homozygosity mapping. Within that region, we further identified HPS5 (HPS5 Biogenesis Of Lysosomal Organelles Complex 2 Subunit 2) as a strong candidate gene, since HPS5 variants have been identified in humans and animals with Hermansky-Pudlak syndrome 5 or oculocutaneous albinism. A homozygous c.2571-1G>A acceptor splice-site variant located in intron 16 of HPS5 was identified in pink-eye cats. Segregation of the variant was 100% consistent with the inheritance pattern. Genotyping of 170 cats from 19 breeds failed to identify a single carrier in non-Donskoy cats. The c.2571-1G>A variant leads to HPS5 exon-16 splicing that is predicted to produce a 52 amino acids in-frame deletion in the protein. These results support an association of the pink-eye phenotype with the c.2571-1G>A variant. The pink-eye Donskoy cat extends the panel of reported HPS5 variants and offers an opportunity for in-depth exploration of the phenotypic consequences of a new HPS5 variant.

Genetic Instability of a Polydactyl Hypopigmented Cat With Squamous Cell Carcinoma-A Case Report

Polydactyly, hypopigmentation, and squamous cell carcinoma are common in cats. However, a cat exhibiting all of these conditions has not yet been reported. This study presents the case of a 14- year-old male Mexican cat, hypopigmented, with supernumerary fingers, two preaxial and one on each posterior limb, admitted to the clinic with a lesion in the left periocular region. The cat was subjected to a general physical examination, blood, and urine chemistry, as well as a biopsy and genomic instability assessment with an analysis of the red blood cells (RBC) micronucleated erythrocytes (RBC-MNE) in the peripheral blood. The biopsy was positive for squamous cell carcinoma, and the RBC-MNE count (8.6 MNE/1000 erythrocytes) was high compared to that previously described in other domestic cats or wild cats. Thus, the genomic instability of the RBC-MNE could be used as an indicator to identify clinical conditions of felines, particularly those with one of the characteristics exhibited by this Mexican cat. The RBC-MNE test is the most widely used in the world for the evaluation of DNA damage, but to our knowledge, it has not been used to identify vulnerable non-human specimens.

A genome-wide scan study identifies a single nucleotide substitution in the tyrosinase gene associated with white coat colour in a red deer (Cervus elaphus) population

Background

Red deer with very pale coat colour are observed sporadically. In the red deer (Cervus elaphus) population of Reinhardswald in Germany, about 5% of animals have a white coat colour that is not associated with albinism. In order to facilitate the conservation of the animals, it should be determined whether and to what extent brown animals carry the white gene. For this purpose, samples of one white hind and her brown calf were available for whole genome sequencing to identify the single nucleotide polymorphism(s) responsible for the white phenotype. Subsequently, samples from 194 brown and 11 white animals were genotyped.

Results

Based on a list of colour genes of the International Federation of Pigment Cell Societies, a non-synonymous mutation with exchange of a glycine residue at position 291 of the tyrosinase protein by arginine was identified as the cause of dilution of the coat colour. A gene test led to exactly matching genotypes in all examined animals. The study showed that 14% of the brown animals carry the white gene. This provides a simple and reliable way of conservation for the white animals. However, results could not be transferred to another, unrelated red deer population with white animals. Although no brown animals with a white tyrosinase genotype were detected, the cause for the white colouring in this population was different.

Conclusions

A gene test for the conservation of white red deer is available for the population of the Reinhardswald. While mutations in the tyrosinase are commonly associated with oculocutaneous albinism type 1, the amino acid exchange at position 291 was found to be associated with coat colour dilution in Cervus elaphus.

TYR Gene in Llamas: Polymorphisms and Expression Study in Different Color Phenotypes

Tyrosinase, encoded by TYR gene, is an enzyme that plays a major role in mammalian pigmentation. It catalyzes the oxidation of L-dihydroxy-phenylalanine (DOPA) to DOPA quinone, a precursor of both types of melanin: eumelanin and pheomelanin. TYR is commonly known as the albino locus since mutations in this gene result in albinism in several species. However, many other TYR mutations have been found to cause diluted phenotypes, like the Himalayan or chinchilla phenotypes in mice. The llama (Lama glama) presents a wide variety of coat colors ranging from non-diluted phenotypes (eumelanic and pheomelanic), through different degrees of dilution, to white. To investigate the possible contribution of TYR gene to coat color variation in llamas, we sequenced TYR exons and their flanking regions and genotyped animals with diluted, non-diluted, and white coat, including three blue-eyed white individuals. Moreover, we analyzed mRNA expression levels in skin biopsies by qPCR. TYR coding region presented nine SNPs, of which three were non-synonymous, c.428A > G, c.859G > T, and c.1490G > T. We also identified seven polymorphisms in non-coding regions, including two microsatellites, an homopolymeric repeat, and five SNPs: one in the promoter region (c.1-26C > T), two in the 3'-UTR, and two flanking the exons. Although no complete association was found between coat color and SNPs, c.1-26C > T was partially associated to diluted phenotypes. Additionally, the frequency of the G allele from c.428A > G was significantly higher in white compared to non-diluted. Results from qPCR showed that expression levels of TYR in white llamas were significantly lower (p < 0.05) than those in diluted and non-diluted phenotypes. Screening for variation in regulatory regions of TYR did not reveal polymorphisms that explain such differences. However, data from this study showed that TYR expression levels play a role in llama pigmentation.

Mocha tyrosinase variant: a new flavour of cat coat coloration

A novel coloration named ‘mocha’ has been identified in the Burmese cat breed from Thailand. Tyrosinase (TYR) mutations are known to be associated with coat coloration in cats, such as the sable Burmese, the points of the Siamese and albino cats. Additionally, sable Burmese that produced mocha‐colored cats had unexpected genotypes for TYR. Therefore, TYR was considered a candidate gene for mocha in cats. Sanger sequencing for genomic DNA revealed NC_018732.3:chromosome D1:45 898 609_45 898 771dup in exon 2 and intron 2 of TYR. Transcription analysis using cDNA detected c.820_936delinsAATCTC (p.I274_L312delinsNL), which caused a 111‐bp (37 amino acid) deletion in the reading frame of TYR. The identified variant was concordant with the phenotype and segregated with TYR variants in a pedigree of 12 Burmese cats. This findings of this study suggest that TYR is associated with the mocha coloration in cats. The new color variant adds to the allelic series for TYR (C > c^b = c^s > c, c²) and is recessive to full color (C); however, interactions with the c^b and c^s alleles are unclear due to the temperature‐sensitivity of the alleles.

Comparative skin transcriptome of two Oujiang color common carp (Cyprinus carpio var. color) varieties

Body color variation has long been a hot research topic in evolutionary and functional biology. Oujiang color common carp (Cyprinus carpio var. color) is a well-known economical and ornamental fish. Three main types of pigments and four distinct color patterns are typical characters of Oujiang color common carp, which makes it an excellent fish model to study body coloration. In this study, skin transcriptome assembly and comparisons were conducted in two Oujiang color common carp varieties: whole red and whole white. Transcriptome comparison revealed that more differentially expressed energy metabolism genes were upregulated in whole white compared to whole red. The results indicated that energy metabolism genes might be strongly associated with environmental adaption and growth performance and likely affect the red and white color formation in Oujiang color common carp. Our study provided direct guidance for the aquaculture industrials of Oujiang color common carp and presented valuable genetic resources for body color research in fish.

Five alternative splicing variants of the TYR gene and their different roles in melanogenesis in the Muchuan black-boned chicken

1. The TYR gene encodes tyrosinase, a multifunctional enzyme that is essential for melanin biosynthesis in melanocytes. This experiment involved the cloning and characterisation of the TYR gene in chicken. Five alternative splice variants were identified in the black feather bulb and designated as TYR-AS1, TYR-AS2, TYR-AS3, TYR-AS4 and TYR-AS5. 2. Among the 11 chicken tissues examined, the feather bulb, comb and skin showed higher levels of all TYR variants. All TYR variants were expressed at significantly different levels in black and white feather bulbs (P < 0.05) and may be involved in melanin formation in plumage. Only TYR-AS1, which plays an important role in muscle melanogenesis, was significantly differentially expressed between black and white muscle (P < 0.01). All TYR variants were expressed at significantly different levels in black and white skin (P < 0.01). 3. The mRNA expression levels of the 5 variants were closely associated with skin melanogenesis in the chicken. These findings provide new clues to the molecular mechanism of melanin formation in the Muchuan black-boned chicken.

Applications and efficiencies of the first cat 63K DNA array

The development of high throughput SNP genotyping technologies has improved the genetic dissection of simple and complex traits in many species including cats. The properties of feline 62,897 SNPs Illumina Infinium iSelect DNA array are described using a dataset of over 2,000 feline samples, the most extensive to date, representing 41 cat breeds, a random bred population, and four wild felid species. Accuracy and efficiency of the array’s genotypes and its utility in performing population-based analyses were evaluated. Average marker distance across the array was 37,741 Kb, and across the dataset, only 1% (625) of the markers exhibited poor genotyping and only 0.35% (221) showed Mendelian errors. Marker polymorphism varied across cat breeds and the average minor allele frequency (MAF) of all markers across domestic cats was 0.21. Population structure analysis confirmed a Western to Eastern structural continuum of cat breeds. Genome-wide linkage disequilibrium ranged from 50–1,500 Kb for domestic cats and 750 Kb for European wildcats (Felis silvestris silvestris). Array use in trait association mapping was investigated under different modes of inheritance, selection and population sizes. The efficient array design and cat genotype dataset continues to advance the understanding of cat breeds and will support monogenic health studies across feline breeds and populations.

Molecular cloning and expression analysis of tyr and tyrp1 genes in normal and albino yellow catfish Tachysurus fulvidraco

The full-length complementary DNA of two genes related to vertebrate albinism, the tyrosinase gene tyr and tyrosinase-related protein 1 gene tyrp1, were cloned and analysed from normal and albino yellow catfish Tachysurus fulvidraco. The open reading frames (ORF) of tyr and tyrp1 encode putative peptides of 533 and 526 amino acids (amino-acid), both of which possess two conserved copper binding sites. The homologous identities of deduced amino-acid sequences showed that both Tyr and Tyrp1 of T. fulvidraco share considerable similarity with that of channel catfish Ictalurus punctatus. Both tyr and tyrp1 were expressed in a wide range of adult tissues. Tyr gene had the highest expression level in the brain of both normal and albino T. fulvidraco. Tyrp1 had the highest expression level in the skin of normal groups, and the fin of albino groups. The messenger (m)RNA expressions of tyr and tyrp1 were detectable at different early developmental stages and varied with embryonic and larval growth. Tyr and tyrp1 mRNA have obvious tissue specificity both in normal and albino T. fulvidraco and higher expression levels were detected in the normal group revealing that tyr and tyrp1 may have an important role in pigmentation. These results will provide useful data for understanding the molecular mechanism of melanin formation and the occurrence of albinism in T. fulvidraco.

Identification and characterization of the tyrosinase gene (TYR) and its transcript variants (TYR_1 and TYR_2) in the crab-eating macaque (Macaca fascicularis)

Tyrosinase is a copper-containing enzyme that regulates melanin biosynthesis and is encoded by the tyrosinase (TYR) gene. Previous studies demonstrated that mutations in TYR could lead to oculocutaneous albinism type 1 (OCA1) owing to the failure of melanin formation. Although a previous study found that albinism in the rhesus monkey was derived from a mutation in TYR, the identification and characterization of this gene in non-human primates has not been achieved thus far. Thus, using the rapid amplification of cDNA ends (RACE) and internal reverse transcription PCR (RT-PCR) we identified the full-length sequence of TYR in the crab-eating macaque, and two different transcript variants (TYR_1 and TYR_2). While TYR_1 comprised five exons and its coding sequence was highly similar to that of humans, TYR_2 comprised four exons and was generated by a third-exon-skipping event. Interestingly, these two transcripts were also present in the African green monkey (Old World monkey) and the common marmoset (New World monkey). Deduced amino acid sequence analyses revealed that TYR_2 had a shorter C-terminal region than TYR_1 owing to the exon-skipping event. Thus, the present study is the first to identify and characterize a full-length TYR gene in a non-human primate, while the further validation of the third-exon-skipping in TYR indicates that this event is well conserved in the primate lineage. Therefore, this study provides useful and important information for the study of albinism using non-human primate models.

A novel nonsense mutation in the tyrosinase gene is related to the albinism in a capuchin monkey (Sapajus apella)

Background

Oculocutaneous Albinism (OCA) is an autosomal recessive inherited condition that affects the pigmentation of eyes, hair and skin. The OCA phenotype may be caused by mutations in the tyrosinase gene (TYR), which expresses the tyrosinase enzyme and has an important role in the synthesis of melanin pigment. The aim of this study was to identify the genetic mutation responsible for the albinism in a captive capuchin monkey, and to describe the TYR gene of normal phenotype individuals. In addition, we identified the subject’s species.

Results

A homozygous nonsense mutation was identified in exon 1 of the TYR gene, with the substitution of a cytosine for a thymine nucleotide (C64T) at codon 22, leading to a premature stop codon (R22X) in the albino robust capuchin monkey. The albino and five non-albino robust capuchin monkeys were identified as Sapajus apella, based on phylogenetic analyses, pelage pattern and geographic provenance. One individual was identified as S. macrocephalus.

Conclusion

We conclude that the point mutation C64T in the TYR gene is responsible for the OCA1 albino phenotype in the capuchin monkey, classified as Sapajus apella.

Electronic supplementary material

The online version of this article (doi:10.1186/s12863-017-0504-8) contains supplementary material, which is available to authorized users.

DNA mutations of the cat: the good, the bad and the ugly

PRACTICAL RELEVANCE

The health of the cat is a complex interaction between its environment (nurture) and its genetics (nature). Over 70 genetic mutations (variants) have been defined in the cat, many involving diseases, structural abnormalities and clinically relevant health concerns. As more of the cat's genome is deciphered, less commonly will the term 'idiopathic' be used regarding the diagnosis of diseases and unique health conditions. State-of-the-art health care will include DNA profiling of the individual cat, and perhaps its tumor, to establish the best treatment approaches. Genetic testing and eventually whole genome sequencing should become routine diagnostics for feline health care.

GLOBAL IMPORTANCE

Cat breeds have disseminated around the world. Thus, practitioners should be aware of the breeds common to their region and the mutations found in those regional populations. Specific random-bred populations can also have defined genetic characteristics and mutations.

AUDIENCE

This review of 'the good, the bad and the ugly' DNA variants provides the current state of knowledge for genetic testing and genetic health management for cats. It is aimed at feline and general practitioners wanting to update and review the basics of genetics, what tests are available for cats and sources for genetic testing. The tables are intended to be used as references in the clinic. Practitioners with a high proportion of cat breeder clientele will especially benefit from the review.

EVIDENCE BASE

The data presented is extracted from peer-reviewed publications pertaining to mutation identification, and relevant articles concerning the heritable trait and/or disease. The author also draws upon personal experience and expertise in feline genetics.

Endogenous retrovirus insertion in the KIT oncogene determines white and white spotting in domestic cats

The Dominant White locus (W) in the domestic cat demonstrates pleiotropic effects exhibiting complete penetrance for absence of coat pigmentation and incomplete penetrance for deafness and iris hypopigmentation. We performed linkage analysis using a pedigree segregating White to identify KIT (Chr. B1) as the feline W locus. Segregation and sequence analysis of the KIT gene in two pedigrees (P1 and P2) revealed the remarkable retrotransposition and evolution of a feline endogenous retrovirus (FERV1) as responsible for two distinct phenotypes of the W locus, Dominant White, and white spotting. A full-length (7125 bp) FERV1 element is associated with white spotting, whereas a FERV1 long terminal repeat (LTR) is associated with all Dominant White individuals. For purposes of statistical analysis, the alternatives of wild-type sequence, FERV1 element, and LTR-only define a triallelic marker. Taking into account pedigree relationships, deafness is genetically linked and associated with this marker; estimated P values for association are in the range of 0.007 to 0.10. The retrotransposition interrupts a DNAase I hypersensitive site in KIT intron 1 that is highly conserved across mammals and was previously demonstrated to regulate temporal and tissue-specific expression of KIT in murine hematopoietic and melanocytic cells. A large-population genetic survey of cats (n = 270), representing 30 cat breeds, supports our findings and demonstrates statistical significance of the FERV1 LTR and full-length element with Dominant White/blue iris (P < 0.0001) and white spotting (P < 0.0001), respectively.

Association of Tyrosinase (TYR) and Tyrosinase-related Protein 1 (TYRP1) with Melanic Plumage Color in Korean Quails (Coturnix coturnix)

TYR (Tyrosinase) and TYRP1 (Tyrosinase-related protein 1) play crucial roles in determining the coat color of birds. In this paper, we aimed to characterize the relationship of TYR and TYRP1 genes with plumage colors in Korean quails. The SNPs were searched by cDNA sequencing and PCR-SSCP in three plumage color Korean quails (maroon, white and black plumage). Two SNPs (367T→C and 1153C→T) were found in the coding region of TYRP1 gene, but had no significant association with plumage phenotype in Korean quails. The expression of TYR was higher in black plumage quails than that in maroon plumage quails. In contrast, the expression of TYRP1 was lower in black plumage quails than that in maroon plumage quails. This study suggested that the melanic plumage color in Korean quails may be associated with either increased production of TYR or decreased production of TYRP1.

Mutations of TYR and MITF Genes are Associated with Plumage Colour Phenotypes in Geese

The polymorphism of microphthalmia-associated transcription factor (MITF) and tyrosinase (TYR) genes have been proposed to play a vital role in coat colour genesis in mammals, but their role remains ambiguous in geese at best. Here, we cloned and sequenced 1,397 bp coding region of MITF gene and a 588 bp fragment of TYR exon 1 for polymorphism analysis among 157 domestic geese showing three types of plumage colour. We detected a total of three SNPs (c.280T>C, c.345G>A, and c.369G>A) in TYR and six haplotypes (H1–H6). Among them, haplotypes H1, H2, H3, and H5 were significantly associated with white plumage trait of Zhedong White Geese. However, only diplotype H1H1 and H3H5 were significantly associated with white plumage trait of Zhedong White Geese (p<0.01). We only detected one SNP (c.1109C>T) for MITF gene and found that genotype CT and TT were significantly associated with white plumage trait of Zhedong White Geese. Briefly, our study suggested an association between polymorphisms of TYR and MITF genes and the plumage colour trait in domestic geese.

Accumulating mutations in series of haplotypes at the KIT and MITF loci are major determinants of white markings in Franches-Montagnes horses

Coat color and pattern variations in domestic animals are frequently inherited as simple monogenic traits, but a number are known to have a complex genetic basis. While the analysis of complex trait data remains a challenge in all species, we can use the reduced haplotypic diversity in domestic animal populations to gain insight into the genomic interactions underlying complex phenotypes. White face and leg markings are examples of complex traits in horses where little is known of the underlying genetics. In this study, Franches-Montagnes (FM) horses were scored for the occurrence of white facial and leg markings using a standardized scoring system. A genome-wide association study (GWAS) was performed for several white patterning traits in 1,077 FM horses. Seven quantitative trait loci (QTL) affecting the white marking score with p-values p≤10(-4) were identified. Three loci, MC1R and the known white spotting genes, KIT and MITF, were identified as the major loci underlying the extent of white patterning in this breed. Together, the seven loci explain 54% of the genetic variance in total white marking score, while MITF and KIT alone account for 26%. Although MITF and KIT are the major loci controlling white patterning, their influence varies according to the basic coat color of the horse and the specific body location of the white patterning. Fine mapping across the MITF and KIT loci was used to characterize haplotypes present. Phylogenetic relationships among haplotypes were calculated to assess their selective and evolutionary influences on the extent of white patterning. This novel approach shows that KIT and MITF act in an additive manner and that accumulating mutations at these loci progressively increase the extent of white markings.

Pleiotropic effects of coat colour-associated mutations in humans, mice and other mammals

The characterisation of the pleiotropic effects of coat colour-associated mutations in mammals illustrates that sensory organs and nerves are particularly affected by disorders because of the shared origin of melanocytes and neurocytes in the neural crest; e.g. the eye-colour is a valuable indicator of disorders in pigment production and eye dysfunctions. Disorders related to coat colour-associated alleles also occur in the skin (melanoma), reproductive tract and immune system. Additionally, the coat colour phenotype of an individual influences its general behaviour and fitness. Mutations in the same genes often produce similar coat colours and pleiotropic effects in different species (e.g., KIT [reproductive disorders, lethality], EDNRB [megacolon] and LYST [CHS]). Whereas similar disorders and similar-looking coat colour phenotypes sometimes have a different genetic background (e.g., deafness [EDN3/EDNRB, MITF, PAX and SNAI2] and visual diseases [OCA2, RAB38, SLC24A5, SLC45A2, TRPM1 and TYR]). The human predilection for fancy phenotypes that ignore disorders and genetic defects is a major driving force for the increase of pleiotropic effects in domestic species and laboratory subjects since domestication has commenced approximately 18,000 years ago.

Genetics of Pigmentation in Dogs and Cats

Color variation in companion animals has long been of interest to the breeding and scientific communities. Simple traits, like black versus brown or yellow versus black, have helped to explain principles of transmission genetics and continue to serve as models for studying gene action and interaction. We present a molecular genetic review of pigmentary variation in dogs and cats using a nomenclature and logical framework established by early leaders in the field. For most loci in which molecular variants have been identified (nine in dogs and seven in cats), homologous mutations exist in laboratory mice and/or humans. Exceptions include the K locus in dogs and the Tabby locus in cats, which give rise to alternating stripes or marks of different color, and which illustrate the continued potential of coat color genetics to provide insight into areas that transcend pigment cell biology.

Genetic testing in domestic cats

Varieties of genetic tests are currently available for the domestic cat that support veterinary health care, breed management, species identification, and forensic investigations. Approximately thirty-five genes contain over fifty mutations that cause feline health problems or alterations in the cat's appearance. Specific genes, such as sweet and drug receptors, have been knocked-out of Felidae during evolution and can be used along with mtDNA markers for species identification. Both STR and SNP panels differentiate cat race, breed, and individual identity, as well as gender-specific markers to determine sex of an individual. Cat genetic tests are common offerings for commercial laboratories, allowing both the veterinary clinician and the private owner to obtain DNA test results. This article will review the genetic tests for the domestic cat, and their various applications in different fields of science. Highlighted are genetic tests specific to the individual cat, which are a part of the cat's genome.

Feline deafness

Cats have among the best hearing of all mammals in that they are extremely sensitive to a broad range of frequencies. The ear is a highly complex structure that is delicately balanced in terms of its biochemistry, types of receptors, ion channels, mechanical properties, and cellular organization. Sensorineural deafness is caused by "flawed" genes that are inherited from one or both parents. Hearing loss can also be acquired as a result of noise trauma from industrialized environment, viral infection, or blunt trauma. To date, it is not practical to intervene and attempt to correct these forms of deafness in cats.

A nonsense mutation in the tyrosinase gene causes albinism in water buffalo

Background

Oculocutaneous albinism (OCA) is an autosomal recessive hereditary pigmentation disorder affecting humans and several other animal species. Oculocutaneous albinism was studied in a herd of Murrah buffalo to determine the clinical presentation and genetic basis of albinism in this species.

Results

Clinical examinations and pedigree analysis were performed in an affected herd, and wild-type and OCA tyrosinase mRNA sequences were obtained. The main clinical findings were photophobia and a lack of pigmentation of the hair, skin, horns, hooves, mucosa, and iris. The results of segregation analysis suggest that this disease is acquired through recessive inheritance. In the OCA buffalo, a single-base substitution was detected at nucleotide 1,431 (G to A), which leads to the conversion of tryptophan into a stop codon at residue 477.

Conclusion

This premature stop codon produces an inactive protein, which is responsible for the OCA buffalo phenotype. These findings will be useful for future studies of albinism in buffalo and as a possible model to study diseases caused by a premature stop codon.

A population genetic database of cat breeds developed in coordination with a domestic cat STR multiplex

A simple tandem repeat (STR) PCR-based typing system developed for the genetic individualization of domestic cat samples has been used to generate a population genetic database of domestic cat breeds. A panel of 10 tetranucleotide STR loci and a gender-identifying sequence tagged site (STS) were co-amplified in genomic DNA of 1043 individuals representing 38 cat breeds. The STR panel exhibits relatively high heterozygosity in cat breeds, with an average 10-locus heterozygosity of 0.71, which represents an average of 38 breed-specific heterozygosities for the 10-member panel. When the entire set of breed individuals was analyzed as a single population, a heterozygosity of 0.87 was observed. Heterozygosities obtained for the 10 loci range from 0.72 to 0.96. The power for genetic individualization of domestic cat samples of the multiplex is high, with a probability of match (p(m)) of 6.2E-14, using a conservative θ = 0.05.

Variation in the tyrosinase gene associated with a white humpback whale (Megaptera novaeangliae)

Tyrosinase-negative oculocutaneous albinism (OCA1A) is characterized by lifelong white hair and skin, a phenotype that has been described in most mammalian species worldwide. Tyrosinase is the key enzyme in melanin biosynthesis, and mutations in the tyrosinase gene result in OCA1A. We examined sequence variation at exon 1 of the tyrosinase gene in 66 humpback whale samples collected from the east coast of Australia, including an anomalously white humpback whale known as "Migaloo." We identified 3 novel variants, including a cytosine deletion that results in a premature stop codon in exon 1. The deletion truncates the tyrosinase protein including the putative catalytic domains that are essential for tyrosinase enzymatic activity. Migaloo was homozygous for this deletion, suggesting that the albino phenotype is a consequence of inactive tyrosinase caused by the frameshift in the tyrosinase gene.

Colours of domestication

During the last decade, coat colouration in mammals has been investigated in numerous studies. Most of these studies addressing the genetics of coat colouration were on domesticated animals. In contrast to their wild ancestors, domesticated species are often characterized by a huge allelic variability of coat-colour-associated genes. This variability results from artificial selection accepting negative pleiotropic effects linked with certain coat-colour variants. Recent studies demonstrate that this selection for coat-colour phenotypes started at the beginning of domestication. Although to date more than 300 genetic loci and more than 150 identified coat-colour-associated genes have been discovered, which influence pigmentation in various ways, the genetic pathways influencing coat colouration are still only poorly described. On the one hand, similar coat colourations observed in different species can be the product of a few conserved genes. On the other hand, different genes can be responsible for highly similar coat colourations in different individuals of a species or in different species. Therefore, any phenotypic classification of coat colouration blurs underlying differences in the genetic basis of colour variants. In this review we focus on (i) the underlying causes that have resulted in the observed increase of colour variation in domesticated animals compared to their wild ancestors, and (ii) the current state of knowledge with regard to the molecular mechanisms of colouration, with a special emphasis on when and where the different coat-colour-associated genes act.

Feline genetics: clinical applications and genetic testing

DNA testing for domestic cat diseases and appearance traits is a rapidly growing asset for veterinary medicine. Approximately 33 genes contain 50 mutations that cause feline health problems or alterations in the cat's appearance. A variety of commercial laboratories can now perform cat genetic diagnostics, allowing both the veterinary clinician and the private owner to obtain DNA test results. DNA is easily obtained from a cat via a buccal swab with a standard cotton bud or cytological brush, allowing DNA samples to be easily sent to any laboratory in the world. The DNA test results identify carriers of the traits, predict the incidence of traits from breeding programs, and influence medical prognoses and treatments. An overall goal of identifying these genetic mutations is the correction of the defect via gene therapies and designer drug therapies. Thus, genetic testing is an effective preventative medicine and a potential ultimate cure. However, genetic diagnostic tests may still be novel for many veterinary practitioners and their application in the clinical setting needs to have the same scrutiny as any other diagnostic procedure. This article will review the genetic tests for the domestic cat, potential sources of error for genetic testing, and the pros and cons of DNA results in veterinary medicine. Highlighted are genetic tests specific to the individual cat, which are a part of the cat's internal genome.