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Originally Posted by pstinard  Hi Diana, just because a dog looks piebald doesn't mean that it is caused by a mutation in the piebald gene--there could be other as-yet undiscovered mutations in other genes that could cause the same appearance. I hadn't seen any proof that the Biewer coat color gene is due to a mutation in the MITF (piebald) gene. This Biewer/Maltese cross proves it to me. Maybe others have done this test, but I hadn't come across it yet. To me, the question remains, is the DNA sequence of the mutation in the piebald gene in Biewers the same as the DNA sequence of the mutation in the Maltese (and other breeds with proven piebald genes)? If so, that would prove to me that the origin of the piebald gene in Biewers is a cross of a Yorkshire Terrier with some other breed carrying a piebald gene. Genetically speaking, new mutations don't occur in the exact same place with exactly the same DNA sequence, and the piebald mutations in other breeds have a very distinctive DNA sequence. I don't care what Mr. Biewer said back in the 1980's, if the piebald gene came from some other breed that was crossed into his Yorkshire Terrier lines, then the Biewer is the result of a mixed breed dog. It wasn't necessarily Mr. Biewer who did this--it could have already been in the lines he got from England. I'm just trying to get at the truth. |
Evidently, the Healthgene company knows the answer to this question, because they have a test for the piebald gene in Yorkshire Terriers and Biewers:
Parti Color Yorkshire Terrier l Coat Color Test - HealthGene
I have sent them a technical email asking them for details about what they are testing for, and how they determine the difference between the piebald mutation and the normal Yorkshire Terrier MITF gene. If the answer is by the presence of the SINE DNA insertion and/or the length polymorphism in the regulatory region of the piebald version of the MITF gene, then it's case closed for me.