Abstract
The roan coat color is described as the dispersion of white hairs within an otherwise solid background color coat. This phenotype is primarily expressed on the body of the horse, with the head and legs exhibiting few to no white hairs. Previous studies mapped the locus for roan to the KIT region and observed linked variants in a small number of breeds. However, utilizing those linked markers to determine the roan genotype in other breeds has seen limited success. In this communication we identify a second roan allele (RN2) which, in conjunction with a previously observed roan allele (RN1) discovered in previous studies, accounts for approximately 74%, or 188 horses, out of a sample size totaling 257 roan horses. These two alleles were present in the non-roan population (N = 3212) at less than 1%, only in horses with light coat color and dilution alleles, likely obscuring the roan phenotype. Future work is required to identify additional alleles responsible for additional roan-type horse coat color phenotypic variation.