HYPERVARIABLE YELLOW (A(HVY)), A NEW MURINE AGOUTI MUTATION - A(HVY) DISPLAYS THE LARGEST VARIATION IN COAT COLOR PHENOTYPES OF ALL KNOWN AGOUTI ALLELES

A new coat color mutation, which occurred spontaneously in the C3H/HeJ strain, has been identified, The original C3H/HeJ male mouse carrying the mutation was unusual because its coat color appeared mostly yello w, in contrast to the wild-type agouti coat normally exhibited by mice of the C3H/HeJ strain, Genetic crosses showed that the mutant phenoty pe was inherited as a single autosomal dominant gene, The mutation was backcrossed onto a C57BL/6J background and tested for allelism with t he agouti locus, The results showed that the mutation, named hypervari able yellow (A(hvy)), is a new allele of the agouti locus. A(hvy) is u nique because mice carrying the mutation can display a range of coat c olor from pure yellow to almost pure black, The A(hvy) mutation is res ponsible for the largest range of coat color phenotypes yet identified for any single agouti mutation.