Canine Long Hair – L Locus
Hair length in dogs is generally classified as either canine long hair (the Golden Retriever) or short (the Labrador Retriever), and is under the control of two alleles: L > l. Taking a candidate approach, Housley an Venta (2006) identified a coding variant in FGF5 gene (fibroblast growth factor), associated with long hair. A later survey showed that FGF559F alele was fixed (or nearly fixed) within most long hair breeds, consistent with a general theme that most traits shared across breeds have a common genetic basis.
The Afghan Hound and the Yorkshire Terrier are notable exceptions, however, for which long hair is not associated with the FGF559F allele, indicating that an additional FGF5 allele or a different gene is responsible for increased hair length in these breeds.
Cadieu, E., Neff, M.W., Quignon, P., Walsh, K., Chase, K., Parker, H.G., Vonholdt, B.M., Rhue, A., Boyko, A., Byers, A., et al. (2009). Coat variation in the domestic dog is governed by variants in three genes. Science 326, 150–153.
Housley, D.J.E., and Venta, P.J. (2006). The long and the short of it: evidence that FGF5 is a major determinant of canine “hair”-itability. Anim. Genet. 37, 309–315.