Wednesday, July 13, 2011

Guess the Genotype #7

Can you guess this dog's genotype?

 Image is under a Creative Commons license at Wikimedia Commons.

Click "read more" to see my answer!

This is a Samoyed. The breed is white, biscuit, cream, or white and biscuit. This dog appears to be a solid white rather than cream, though it is difficult to tell since white coats are easily discolored. There are several things that can cause a dog to be solid white or to appear white.

White German shepherds are in fact a pale form of recessive red and will nearly always have a cream-tinted coat. This is most likely caused in combination with a modifier that dilutes the red in the coat to this pale cream color. This is a possibility.

Extreme white piebald can cause a solid white dog. It is unusual for the dog to completely lack color, however, and this also usually combined with a loss of some pigment in the eye rims, lips, and/or nose. Since this dog has fully pigmented skin, this is unlikely. However, piebalding is seen in the Samoyed breed.

A solid white dog can also be caused by homozygous merle, though again it is very rare for the dog to be solid white, pigment is nearly always lost, and the eyes are most often blue in whole or in part. This, however, is not possible because merle is not known to occur in Samoyeds.

So, what is this dog? In all likelihood, this dog is in fact ee recessive red with modifiers to turn in near-white.

However, there is also some evidence that shows that it could be caused by a combination of the recessive red gene (which removes all black pigment from the coat) and the recessive black gene (which removes all red pigment from the coat) working together. Though there is not a lot of evidence for it, it is an interesting hypothesis nonetheless. For the sake of argument, I am going to claim this to be the case. Thus:

This dog is possibly aa ee or fully unpigmented white (with pigmented skin).


  1. Our Saluki Spooky is an extreme white parti. He had cream spots on his head and back as a baby that faded. If you look closely you can see some small spots on his back. He also has a lot of pigment on his skin, most of his body is pigmented; he may have ticking, his full sister Cida has very heavy ticking.

    (This is Jess, btw, husband was signed in and I'm too lazy to sign out.)

  2. What I find interesting is that the inheritance of dark to light colored e/e's varies from breed to breed and from line to line. In most golden retrievers, darker colors are dominant (probably incomplete dominant) to lighter colors, fitting the chinchilla gene theory.

    Red poodles, however, are produced by a recessive allele (f):

    Different breeds have different modifiers.

  3. It is quite possible the dog in my post is an extreme white piebald. It's difficult to tell in a dog like that, but it is exceptionally common for extreme whites to have loss of pigment, especially around the eyes, if they have no colored spots at all. Spooky is a beautiful dog, by the way.

    I would love to see more research done into what controls red intensity in the various breeds. I've seen at least three proposed theoretical genes. I do wonder is there could be linkage between the chinchilla gene and the recessive red gene since so often a puppy will be born that is both and will end up looking quite different from the parents. For example, in German Shepherds the "white" puppies are born from dogs with darker red coloration if the parents are not white themselves.