Japanese Chin Coat Color DNA Study

an update and information page for the owners of Japanese Chin who have contributed DNA brushes to the study


This webpage was posted on Oct. 21, 2006 and last updated on JUne 1, 2008 by Sheila Schmutz

The Study

We are grateful to Leanne Bertani, M.D. for coordinating the samples, photos, consent forms, etc. for this study conducted on behalf of the Japenese Chin Club of America, who funded the study. We also thank the dogs and their owners who contributed to the study. The dogs donated DNA via cheek brushes, hair clippings and posed for the photographs.

The 11 DNA brushes arrived in Saskatoon at our lab by October, 2006. Two more arrived a few months later. The collection represents a wide variety of coat colors, but as we've discovered, probably not all the possible colors that occur.

Call names that were provided will be used, not the registered names of the dogs. Generic information will be posted on this site. Specific information will be emailed to the owner of a specific dog. We have begun DNA testing but it will likely take a couple of months before we complete the testing and analyze the results.


The coat colors listed for Japanese Chin include:


The major question being asked is do both "e/e" clear red and "ay/-" sable red occur in Japanese Chin? Therefore the first DNA test run was to detect "e/e".

Lilly was the first Chin whose brush arrived. She tested E/e which means her reddish color is of the sable type caused by an ay allele. Her owners say she has a few black hairs intermingled amongst her red ones, which is another typical feature of sable red dogs. These are not obvious on the photo however.

Elmo, shown on the left, is considered lemon whereas YaYa, on the right, is considered red. Both tested "e/e" or clear red. The difference in shade is caused by another gene.

Ruby, on the right, is also "e/e" clear red.

Elmo, YaYa, and Ruby all tested at/at at the agouti gene. Why aren't they black-and-tan then? That's because e/e is epistatic or masks any allele at any other locus that causes black hair anywhere on the body.

Tootie, shown on the left, is another Chin that tested "e/e" or clear red. She is ay/at and so is actually a sable red too. Although most sables, like Lilly above have a few black hairs, because Tootie is "e/e" these would not occur in her.


Marik, shown on the left, is the sire of Czar, on the right, a brown and white pup. Both tested E/e. Marik is therefore a sable red. Czar must have one KB allele since he is brown, whereas Marik would be ky/ky.

Marik tested ay/at. Since ay is dominant, to at and he is ky/ky, his sable coloration is what shows.

Czar tested ay/ay, or homozygous for sable but isn't showing sable coloration. That is because he is KB/ky and the KB masks the alleles of the agouti gene.

Czar is the only Japanes Chin in this group that tested b/b at the TYRP1 locus. Both b alleles are the bs allele. His sire, Marik is the only other dog that had a b allele.

Baby, on the left, is a black dog with white, typically. She tested E/e at MC1R and must has one KB allele and one ky allele. Like Czar her KB allele prevents her tan points from showing. She tested at/at.

Rudy, on the right, is another black and white dog. However he tested E/E at MC1R and KB/KB. He is ay/ay, but again his sable is masked because he has a KB allele.


Tink is a black-and-tan dog with white, typically called a tricolor. She tested E/e at MC1R and "at/at". She also tested ky /ky, as expected, which allows her tan points to show.


What gene causes the white markings of Japanese Chin? Karlsson et al. (2007) reported that the gene MITF caused white markings in some breeds. We therefore expanded this study to include many breeds and indeed the same mutation that causes piebald to extreme white spotting in their report, is present in all Chin. Since this pattern is "fixed" in Chin, i.e. all have it, they also are all "s/s".


Links

Dog Coat Color Genetics Main Page

Japanese Chin Club of America

Japanese Chin Club of America Breed Standard includes an explanation of coat colors accepted for show

Colors of the Japanese Chin by Adrienne Wilder


Sheila M. Schmutz, Ph.D.

Department of Animal and Poultry Science

University of Saskatchewan

Saskatoon, Canada S7N 5A8

phone: (306)966-4153 fax: (306)966-4151

e-mail sheila.schmutz@usask.ca