Genetics Picture

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Piebald white spotting

It is very unclear on how piebald white spotting is inherited. The generally accepted theory is that there is an incomplete dominant gene, S (spotting), which gives any amount of white spotting. ss would then signify a cat without white. Ss would mean bi-color (white paws and legs, white on the breast and white in the face) and SS would be a highly graded white cat, like harlequin and van. It is without a doubt not the whole truth. There must be more genes that modify the expressions of these genes, since there are not three sharply divided groups of piebald cats, but instead the variation seem to be continuous.

Breeders of Birman can hardly be satisfied with the above mentioned theory. Birmans have white paws, and when two Birmans are mated all kittens get white paws. One never gets any cat completely without white and one never gets a harlequin or van colored cat.

Hence one has come up with the theory of a recessive gene for white paws. This is denominated as g (gloves). GG is according to this theory a cat without white. Gg could possibly give a cat with a white medallion or a white spot on the tummy and gg would give white paws and maybe a bit of white on tummy and throat (these spots would be concealed in the light coat of the Birman).

Now and then one sees examples of that these theories together are not enough to explain the piebald white spotting, but yet there are no other theories that explains this better. We must take into account that polygenes also are involved in this.