The contribution of retrotransposons to canine genome variation

Domestic dogs, Canis lupus familiaris , have emerged as an important model system for studies of the genetic basis of phenotypes, patterns of genome variation and evolution, and for identifying loci relevant to human health and disease. The emergence of genome-scale sequencing data has revealed a disproportionate contribution of transposable elements to genetic variation in canines relative to humans, including insertions linked to traits and diseases. Insertions include LTR and non-LTR retrotransposons, such as Endogenous Retroviruses (ERVs), Long Interspersed Element-1 (LINE-1), and Short Interspersed Elements (SINEs). LINE-1 is an autonomous retroelement that encodes the proteins necessary for its retrotransposition and is currently active in canines. In addition, proteins encoded by LINE-1 s have mobilized SINEs and created gene retrocopies throughout the canine genome. In this review, we offer an overview of the classes of retrotransposons found in canine genomes and describe their contribution to traits and disease.