Home Page Forums Darwin’s Ark New discovery: another gene that can cause blue eyes in dogs

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    This was discovered by researchers at Embark, the commercial dog ancestry testing company (which is also a research company). From their website:

    “Two genes that influence the Merle (M-locus) and Piebald (S-locus) coat color traits were already known to predict when a dog is more likely to have blue eyes. However, even after taking those two genes into account, some cases of blue eyes remain unexplained. For example, some dog breeds, like Siberian Huskies and [non-merle] tri-colored Australian Shepherds, occasionally have blue eyes which can not be explained by M-locus or S-locus….[W]e discovered a genetic mutation, specifically a duplication of DNA sequence near ALX4 (a gene on dog chromosome 18 involved in craniofacial, skin, and hair follicle development)…we think that this duplication may disrupt the process by which pigment is deposited in the iris of the eye during development. It turns out that this newly discovered genetic variant can help explain up to 75 percent or so of cases of blue eyes in our dataset…”

    (Although they don’t mention it above, albinism, as occasionally seen in Dobermans and a few other breeds, is another already-known genetic cause of a few cases of blue eyes in dogs, as is the “panda” mutation found only in certain German Shepherds.)

    So, if you’ve previously tested your dog with Embark, and your dog has blue eyes or you have reason to suspect it might carry for them, be sure to log in over there and check your dog’s traits results, because they’ve updated all results to reflect this new finding. They’re especially interested to hear from anyone with a blue-eyed dog that ISN’T merle or piebald (or albino or panda) AND also DOESN’T carry this newly discovered mutation, since that will help them clarify just how many cases of blue eyes this finding might still leave unexplained.

    Also of note, it sounds like this mutation more or less behaves in an incompletely dominant fashion. They don’t actually use that term, I’m just inferring it from the fact that they do mention that dogs carrying one copy of this mutation might have just one blue eye, or even no blue eye at all yet still be able to pass blue eyes on to its offspring. They don’t specifically mention split eyes, which I know also sometimes occur in Huskies and some other non-merle dogs, but perhaps that too would fall under the heading of variability in expression seen with this mutation.

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    kathleen morrill

    Excellent summary, Jennifer!

    This is a great example of how citizen science can help power new discoveries. There’s so much to be learned from what *doesn’t* meet our expectations about a dog from their DNA. 🙂

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