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Genome project
Coat Colors & Fur Types
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Feline
Genome project
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Coat Colors & Fur Types
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The mutations that cause several coat colors in cats have now been identified. DNA tests are being developed and will be available as commercial services soon. Tests for agouti, sepia, and points are available. Tests for complete albino, chocolate and cinnamon are under develeopment. Patents are pending for several tests, but licenses will be available to any interested DNA typing service laboratory, worldwide. All tests can be performed on DNA acquired from buccal (cheek) swabs.
BackgroundThe basic coat colors of the cat are defined by less than 10 genes. Fur length and style, ear type, and tail type genes are controlled by at least another 10 major genes. The Lyons' feline genetics laboratory has been identifying pedigrees and collecting DNA samples from cats throughout the world in order to identify the mutations causing cat coat and body traits. The Waltham Pet Nutrition Centre has provided the Lyons' laboratory with DNA samples from their cat colony and Waltham has continued support of the coat color studies. The Winn Feline Foundation and both UC Davis and the UC Davis, School of Veterinary Medicine, Center for Companion Animal Health have also provided support for the research.GeneticsA variety of information is available for the inheritance and genetics of feline coat colors. Our favorite references are provided on the references pages. The table below presents the basic coat color genes for cats. Other modifying genes also exist but are not well documented. Dominant variants (alleles) for each gene are generally written as capital letters. Some colors have more than one variant (allele) and the dominance of the alleles is shown by the greater than ">" symbol. Wildtype implies the most frequent variant found in the feral population, prior to the development of cat breeds. Wildtype variants may or may not be dominant and is some cases, the true wildtype variant may not be known.
Although many of the same breeds are recognized worldwide, different registries accept various breeds in different colors. Within and across breeds, different nomenclature for the same color can be used in different cat associations. Examples are red Abyssinians and cinnamon Oriental Shorthairs. These two names for light brown color represent the same color variant (bl) at the gene called Brown (B). Thus, when mutations for coat color variants are identified, caution should be used with genetic testing and all color variants across breeds and associations should be confirmed to be identical.Additionally, when other color variants, such as dilution, sepia, mink, points, orange and white spotting are also within the same cat, some cats can easily be mislabeled and registered as the wrong color. Genetic testing will allow breeders to correctly identify the color of their cats, preventing misassignment of color class and reducing the need for test crossing. Breeders can also be more confident with the exchange of cats between registeries and parts of the world since they will be able to clearly identify wanted or unwanted carriers of different color vairants. Since breeders will be more confident, they will be able to more readily add genetic diversity to their cats and reduce the need for 8 or longer generation pedigrees. AgoutiThe agouti gene normally makes a cat's fur have more than one band of color, generally black (eumelanin) and yellow (phaeomelanin) bands are present. "Wildtype" agouti cats are brown tabbies. The fur is not actually brown, but the black-yellow-black banding of pigment in the fur makes the cat appear brown. This should not be mistaken with the gene called Brown. The wildtype, agouti variant, A, is dominant, hence cats that are AA or Aa can not be distinguished. Only genetic testing, either with DNA or breeding, can prove a cat to be a carrier. Non-agouti cats, aa, are solid (self) in color. Tabby patterns are still present but are difficult to identify since the fur surrounding the pattern is the same color. Some pattern can often be seen in cats that are orange or orange dilution (cream) solids.
The genetic test can identify if a cat is AA versus Aa, thus can identify cats that are carriers of the solid, non-agouti variant. The test is valid for all colors of cats. The non-agouti variant is caused by a deletion of 3 nucleotides in the exon 2 DNA sequence of the agouti gene, a.k.a. ASIP (agouti signaling protein). Please see the published work by Eizirik et al., for a description of the mutation identification. This test is not under any patent restrictions. This test is currently available through the UC Davis Veterinary Genetics Laboratory and may be offered by other laboratories worldwide. (top)BrownThe gene for brown alters the amount of black pigment only, reducing it to a brown tone. The wildtype variant, B, is normal black, the b variant produces chocolate, a.k.a. chestnut or brown, and the light brown variant, bl, is cinnamon or red in an Abyssinian. Brown tabbies with brown variants at the B gene are lighter brown in color. Breeds such as the Havana Brown are fixed for the brown variant, bb. Red Abysinnians are blbl. Since there is more than one variant, the variants form an "allelic series where B is dominant to b, and b is dominant to bl: B > b > bl. Cats that are bbl are very rare, thus some tone in color could be noticed, but this needs to be supported by genetic testing. Cats that are Orange will also have lighter shades with brown variants. The tabby pattern will also be a lighter shade in tabbies, cats that are AA, or Aa. The mutations for the brown variants have been identified by the Lyons' feline genetics laboratory. The cinnamon variant is a single nucleotide variant that causes a stop in the DNA sequence and inhibits the production of most of the normal protein. The gene for Brown is called TYRP1, tyrosine-related protein 1. The chocolate mutation is currently identified by several mutations that do not appear to alter the normal protein significantly. Thus, more research should help identify the true cause for chocolate within the TYRP1 gene. All chocolate cats tested to date have the same variants, thus, DNA testing for carriers could be performed if related cats are also provided, such as parents or offspring. The DNA tests can distinguish cats that are BB, or Bb, or Bbl, or bbl, or blbl. A patent has been filed for these tests but a license will be available to all interested laboratories. The research describing these mutations have been submitted for publication. This test will become available through the UC Davis Veterinary Genetics Laboratory and may be offered by other laboratories worldwide. The Color gene. C, produces the enzyme Tyrosinase (TYR) which controls melanin production. Mutations in this gene have been shown to cause color variants in other species, such as mice and rabbits. The TYR gene has been implicated to cause cat "point-restriction" color for over 20 years. The wildtype allele, C, produces normal pigment production, regardless of color. The cb variant, a.k.a. sepia or burmese, is a temperature sensitive mutation that causes nearly full color production at the extremities, such as the ears, tails, faces and paws, but less pigment in warmer areas of the cat, such as the body. The produced brown coloration, sable, is still black pigment and has nothing to do with the Brown gene. Cats that are cscs are the familiar points coloration found in Birmaa, Siamese, Himylayans and several other breeds. Full albino cats are cc and this coloaration is now recognized in Colorpoint Shoirthair cats. Since there are multiple variants, the gene has the allelic series, C > cb = cs > c. Cats that are cbcs are intermediate between cbcb and cscs in color and difines the mink Tonkinese. The mutations causing the Color variants are direct DNA changes. The cb mutation causes a change in the protein sequence, as does the mutation for cs, but cs is at a different position in the DNA sequence. The c mutation that leads to complete albinism is a single nucleotide change that stops the DNA seqeunce from producing the full-length normal protein. The DNA test will identify all variants, CC, Ccb, Ccs, Cc, cbcb, cbcs, cbc, cscs, csc and cc. A patent has been filed for these tests but a license will be available to all interested laboratories. The research describing these mutations have been submitted for publication. This test will become available through the UC Davis Veterinary Genetics Laboratory and may be offered by other laboratories worldwide. Research is continuing in the Lyons' feline genetics laboratory to identify many other coat color mutations for cats. DNA samples collected for diversity and gene pool projects are often used to support these studies. Additional samples of cats with different coat colors are always welcome. Please consider participation, you may get your cats tested for free! Please visit the DNA sampling & shipping protocols on how to send in samples. Cats with unusual colors, such as goldens or carmels are highly desired. Cats that are dominant white, hearing and non-hearing, are also highly desired.Join the Project!Breeders and cat owners cat assist the research for PKD in various ways. Some breeders have donated blood samples, PKD status and pedigree information for family studies. Others have donated blood samples from affected cats for mutation screening. Kidneys of deceased cats can be donated for analysis by researchers involved with human PKD studies. Collaborating owners can attend PKD clinics and have a majority of their cats screened for free or for a minimal cost. Some individuals choose to donate money to the Winn Foundation that is specifically marked for PKD research.This research is not breed or association specific!(top)
Last update: November 30, 2004 This site is under continual development. Please visit again soon! Many of the current pages are the place holders for future information. Please provide suggestions to the webmaster: felinegenome@ucdavis.edu |
DNA tests available soon for coat
colors! 
