Unverified Color Mutation in Donskoy Cats

Donskoy (Don Sphynx) founder Irina Nemykina explains in her history of the breed how cats from her Mif cattery were taken to St. Petersburg for research and experimental breeding. Some of the kittens in St. Petersburg were then taken to Ukraine, where they were used to found the Mari’A Neon and Mon Plaisir catteries. Chocolate Donskoys were first noticed in cats descended from these Ukrainian catteries. Donskoy breeders sometimes call this color “Ukrainian chocolate.”

Although current WCF, CFA, and TICA standards for the Donskoy allow all skin colors, the chocolate phenotype, known to be caused by genotype bb or bb1 at the TYRP1 (B) locus, is considered by some experts to be a contamination of the Donskoy from a restricted outcross with Oriental breeds. This outcross was practiced widely in order to remove hair from Oriental cats and create the Peterbald breed. 

With all due respect to the experts, especially to breed founder Irina Nemykina, we think that the Donskoy’s evolution cannot be stopped. Increasing numbers of Donskoy breeders and fans love to see new features (blue eyes, for example) in these beautiful cats, and Donskoy Discovery (as it follows from the cattery name) is not an exception. For more than seven years we have been breeding show-quality Donskoys with a phenotype judges have taken to be chocolate. They do have the paw pads of a chocolate, but their skin color is unusual. We believe it makes them look especially exotic and mysterious. 

Unlike chocolate cats of other breeds our cats’ eyes become bright red in certain lighting conditions. Initially we assumed that this strange eye color resulted from their being both chocolate and dominant-hairless, or perhaps from carrying Cs or Cb genes. But there is evidence from breeders that mating of Ukrainian chocolate Donskoys with Donskoys known through lab testing to have the bb or bb1 genotype did not produce chocolate kittens. 

We have never had our chocolate Donskoys genotyped (there are no labs in Ukraine for color testing), but in order to be able to breed and show them legally, we have agreed to have them documented as having the bb or bb1 chocolate genotype.

But we now have proof that our cats must have some unverified genotype. By extremely lucky coincidence, two solid-black Donskoys, close relatives of our cats, became the foundation of Kathryn Eden's Donskoy cattery in the USA, and a few months ago delivered Milkdud--a kitten of Ukrainian chocolate phenotype (see a picture at Kathryn's Facebook site). Kathryn took a scientific approach and had genetic tests performed on her black breeding pair and two of their kittens: Milkdud and a black sibling of Milkdud from the same litter. All 4 of them are aa BB CC DD EE, which should give them a solid black phenotype. But as you can see, Milkdud is not black.

Thanks to Kathryn's initiative we now have scientific evidence that the chocolate phenotype and unusual eye color of Milkdud, as well as our own cats, are caused not by the known chocolate mutation (b) at the TYRP1 (B) locus, but by a new mutation at B or at some other locus, a mutation for which there is not yet a genetic test. Possible candidates are the other two melanosome transfer and translocation genes: Myosin Va (MYO5A) and RAB27A. Genes involved in the synthesis of eumelanin other than TYRP1, for example, TYRP2, are also possibilities.

There have been reports that some cats have had a diluted-color phenotype without having the dilution genotype (d/d) at the D locus, where D codes for melanophilin (MLPH), one of the three genes involved in melanosome transfer and translocation. Examples are the Barrington Brown cats and the pink-eyed dilution cat. Unfortunately, these cats died before their dilution genes could be found and sequenced.

At the moment, Milkdud’s and our cats’ DNA samples and hairs are under investigation by scientists in genetic laboratories. They can provide the scientific background for registering a new cat color. We will keep our readers informed about the progress and results.  

Also, we would appreciate it very much if you could contribute to our “color adventure” by providing us with relevant information and buccal swabs of your registered Donskoy or Peterbald cats of any color. We need these for our study of the genetics of the genetics of this unverified color mutation, and your cat might have it or be a carrier.