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Coat colours in cats What are 'coat colours'? DNA tests for coat colours Breeds that can be tested The DNA tests for the alleles of the A-, B-, C- and D-locus can help the breeder to be in control of the major coat colours of the kittens born in the next generation. The DNA tests give him a choice to avoid kittens with certain coat colours in his litters or, if he likes, to produce kittens of those colours willingly. Bengaal blue tabby spotted (A-dd) black (aaD-) black tabby spotted (A-D-) The colour alleles that originally were available in only one or two breeds have been introduced in most of the breeds, a process that is still going on. So each of the colour alleles in our cat breeds originates from one and the same mutation that took place many years (many generations) ago. Therefore all the available DNA tests can be applied in almost any breed. Up to now no limitations have been found in terms of rare variants of the colour alleles only occurring in one breed or within a limited group of breeds. The interpretation of the results of the DNA tests for the A-locus and for the D-locus is quite straight forward. In terms of the outcomes of DNA tests for inherited disorders: your cat can be 'clear' from the allele a or d (its genotype is AA or DD), it can be a 'carrier' for the relevant recessive allele a or d (its genotype is Aa or Dd) or it can be 'affected' by the relevant recessive allele (its genotype is aa or dd). The test results for the B-locus and the C-locus may need some extra explanation. You should keep in mind that the test only informs you about the presence or absence of the allele that is tested for. All tests reveal the difference between the heterozygous and the homozygous genotype (so between one or two alleles) but none of the DNA tests gives any information about the other alleles involved. That is why we use the symbol 'N' for these unknown alleles. For the B-locus we get the test results: colour of the eumelanin genotype of the cat tested result of the DNA test for chocolate result of the DNA test for cinnamon black BB NN NN   Bb Nb NN   Bbl NN Nbl chocolate bb bb NN   bbl Nb Nbl cinnamon blbl NN blbl and for the C-locus we get the test results: restriction of the eumelanin genotype of the cat tested result of the DNA test for Burmese result of the DNA test for Siamese full colour CC NN NN   Ccb Ncb NN   Ccs NN Ncs Burmese cbcb cbcb NN Tonkinese cbcs Ncb Ncs Siamese cscs NN cscs The DNA tests on the alleles of the B-locus (chocolate or b, and cinnamon or bl) are of special interest for breeders of cats with the diluted colours lilac (bbdd) and fawn (blbldd). In many of those animals the difference between both colours is often hard to determine. Where the amount of eumelanin in the coat is restricted by the alleles of the C-locus (cb and cs) phenotypically there not much eumelanin left to base a judgement on. With the DNA tests on the B-locus breeders can be sure about the genotype of his breeding animals. burmese lilac: bbcbcbdd burmese lilac: bbcbcbdd en bblcbcbdd burmese lilac: bblcbcbdd burmese fawn blblcbcbdd Breeding policy Testing for coat colours