Since I see p-ter hasn’t posted on this, in Science, Coat Variation in the Domestic Dog Is Governed by Variants in Three Genes:
Coat color and type are essential characteristics of domestic dog breeds. While the genetic basis of coat color has been well characterized, relatively little is known about the genes influencing coat growth pattern, length, and curl. We performed genome-wide association studies of more than 1000 dogs from 80 domestic breeds to identify genes associated with canine fur phenotypes. Taking advantage of both inter- and intrabreed variability, we identified distinct mutations in three genes, RSPO2, FGF5, and KRT71 (encoding R-spondin-2, fibroblast growth factor-5 and keratin-71, respectively), which together account for the majority of coat phenotypes in purebred dogs in the United States. This work illustrates that an array of varied and seemingly complex phenotypes can be reduced to the combinatorial effects of only a few genes.