We all thought we had brindle in dogs pretty much figured out. We all knew that brindle was recessive to dominant black and dominant to wild-type (KB>Kbr>ky). Recent research however, has thrown that idea on it’s head. Researchers in Europe have discovered that, at least in some breeds, brindle dogs test positive for the dominant black allele. That’s right, some brindles test positive for dominant black. Wait you ask...Wouldn't that make them black? Well it turns out, no, it doesn't. In fact, all the brindle dogs tested (14 brindle Boxers and and 10 brindle Great Danes), tested heterozygous for the dominant black allele and wild-type (KBky) .
So what does this mean? Well, that remains to be determined. It may mean that brindle is not at the K locus at all but is a yet to be discovered modifier of dominant black (KB). It’s possible that Akita-inu’s are homozygous for this yet to be determined mutation so that all Akita-inu’s that are positive for the CBD103 G23del mutation (dominant black) are brindle rather than dominant black. It could also mean that their are different types of brindle among dogs with some breeds having a brindle allele at the K locus and some breeds having a modifier at another locus. Or maybe, it’s something entirely different. It’s really too early to say.
In the meantime if any of you have had brindle dogs test positive for Dominant Black I’d like to hear from you! Please comment with your test results and breed.
Candille, S., Kaelin, C. & Cattanach, B. A β-defensin mutation causes black coat color in domestic dogs. Science 318, 1418–1423 (2007).
Ciampolini, R. et al. Characterization of different 5’-untranslated exons of the ASIP gene in black-and-tan Doberman Pinscher and brindle Boxer dogs. Animal genetics 44, 114–7 (2013).
Oguro-okano, M., Honda, M., Yamazaki, K. & Okano, K. Protein Genes , and Their Association with Coat Color Phenotypes in Akita-Inu Dogs. (2011).