A Kit Mutation Associated with Black-Eyed White Phenotype in the Grey Red-Backed Vole, Myodes rufocanus

Abstract. Mutations in genes causing leucism are often accompanied by serious disease limiting individual fitness in laboratory animals. Mammalian species with all-white fur exist in the wild; however, the causative genes have not yet been identified, because of the difficulty of the forward genetic approach—comparisons between individuals with different phenotypes. In this study, we conducted linkage analyses using six candidate gene markers on a wild leucistic female grey red-backed vole (Myodes rufocanus) and inbreeding F1 and F2 offspring displaying variations in coat colors, agouti, and leucism. We found that the white-furred variant was associated with a specific Kit allele characterized by a nonsynonymous substitution at amino acid position 604, leading to the replacement of glycine with arginine. In addition, the leucistic phenotype was accompanied by a small portion of black hairs, which increased with growth. Our results showed a candidate gene causing leucism in viable wild animals and provided an opportunity to consider the necessity to study growth-associated traits for coat color analyses.