Multiple Retrocopies Recently Derived within Canids.

Two transcribed retrocopies of the fibroblast growth factor 4 () gene have previously been described in the domestic dog. An retrocopy on chr18 is associated with disproportionate dwarfism, while an retrocopy on chr12 is associated with both disproportionate dwarfism and intervertebral disc disease (IVDD). In this study, whole-genome sequencing data were queried to identify other retrocopies that could be contributing to phenotypic diversity in canids. Additionally, dogs with surgically confirmed IVDD were assayed for novel retrocopies. Five additional and distinct retrocopies were identified in canids including a copy unique to red wolves (). The retrocopies identified in domestic dogs were identical to domestic dog haplotypes, which are distinct from modern wolf haplotypes, indicating that these retrotransposition events likely occurred after domestication. The identification of multiple, full length retrocopies with open reading frames in canids indicates that gene retrotransposition events occur much more frequently than previously thought and provide a mechanism for continued genetic and phenotypic diversity in canids.