An Expressed Fgf4 Retrogene Is Associated with Breed-Defining Chondrodysplasia in Domestic Dogs

Going Retro In a year celebrating Darwin, the question of how new functional genes arise during evolution is of particular interest. Through a multibreed genetic analysis of the domestic dog, Parker et al. (p. 995 , published online 16 July; see the Perspective by Kaessmann ) find that the short-legged phenotype that characterizes at least 19 common dog breeds, including the corgi, dachshund, and basset hound, is specifically associated with the expression in developing bone of a gene encoding fibroblast growth factor 4 ( fgf4 ), a member of a gene family previously implicated in dwarfism in humans. Interestingly, the culprit fgf4 gene in dogs has the hallmarks of a “retrogene,” a gene that arises when a parental gene is duplicated through an RNA-based copying mechanism.