"Out, damned spot!".

Mice transgenic for the Kit Val620Ala mutation, which in humans has been associated with progressive piebaldism, exhibit dominant white spotting but show no evidence of progressive depigmentation. These results are consistent with the previous hypothesis that progressive piebaldism might result from digenic inheritance, of the KIT(V620A) mutation that causes piebaldism and a second, unknown locus that causes progressive depigmentation.