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

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.