Brown and rust mutants of the Syrian hamster are p and b genes of mammalian coat colors.

The mutant genes of the Syrian hamster, which were originally designated as brown (b) and rust (r), are shown by morphological and phenotypic criteria, as well as by linkage studies in the case of brown, to be homologous with pink-eyed dilution (p) and brown (b), respectively, two well established loci in the genetics of mammalian pigmentation. It is proposed that the two mutants be appropriately redesignated.