Cis- and Trans-Effects Underlying Polar Overdominance at the Callipyge Locus

Abstract

The callipyge phenotype is a muscular hypertrophy of sheep that is characterized by a unique mode of inheritance, referred to as polar overdominance, in which only heterozygous individuals inheriting the CLPG mutation from their sire express the phenotype. We herein report recent advances towards understanding the molecular mechanisms underlying polar overdominance. They involve an interplay between cis- and trans-effects of the CLPG mutation (Fig. 4.1).