Thursday, May 31, 2012

Guess the Genotype #74

Can you guess this dog's genotype? Its breed?

Image is from under a Creative Commons license

This is Cinder, a Catahoula leopard dog. What's her genotype?

Cincer appears to be dominant black. I suspect that she's heterozygous for this as a large portion of Catahoulas are tan point. This would make her Kk black carrying non-black. Due to the prevalence of tan point in the breed, I also believe that she is hiding atat tan point.

Clearly, she's a merle, but is she a single merle or double merle? I have reason to believe that Cinder is MM double merle. Why is that? Genetic testing on merle Catahoulas has shown that many dogs that are believed to be non-merle test positive as merle, and also a number of dogs believed to be single merles test as double merle. It seems that many of the Irish white Catahoulas that are out there are actually double merle dogs. On top of this information, Cinder also has a white ear. She doesn't have a lot of white on her body, and this is quite an unusual feature on a dog who is genetically Irish white. In dogs that are double merle, the white on the head of the dog is frequently more prevalent than what would be seen in a dog with a single copy of the gene or no merle gene at all. I suspect that the white seen on her ears is thanks to two copies of the merle gene.

Thanks to what I said previously, I don't think Cinder has a copy of the Irish white gene. I believe that she's actually SS solid and that the white she has is caused by two copies of the merle gene. Non-merle Catahoulas frequently appear to have little to no white, so this would be appropriate.

So, that's atat Kk MM SS or double merle black (blue merle carrying tan point).


  1. I suspect that there's at least one alternate merle allele in Catahoulas (and other breeds). I am not up on allele nomenclature, but I suspect that eventually we will distinguish the variants of the allele gene. So I propose M1M2 or perhaps M2M2.

    1. It's quite possible. I know they've done some genetic testing on Catahoulas, but I don't know if they've just looked at markers or at the gene in full. I really doubt that every dog has the exact same merle gene, so it would be quite interesting if they did a wide-ranging study.

  2. Coincidentally enough, I came here to seek your thoughts on this dog; ! Do you think it's the same phenomenon?

    1. It's possible, but I really don't think so. It looks like the dog's a tweed. Tweed turns the usual two-shade merle into a more complex color with many different color variations, including the occasional patch of white. It's known to appear in the Australian shepherd breed, which is what that dog appears to be.

      It's also possible that the dog has vitiligo, but tweed seems to be the more probably explanation.

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