Tyrosinase-related protein 1 (TYRP1) gene polymorphism and skin differential expression related to coat color in Mongolian horse

The purpose of this study was to evaluate the association among the polymorphism of the tyrosinase-related protein 1 (TYRP1) gene, differential expression in the skin, and coat color in Mongolian horses. The polymorphisms of TYRP1 in five groups of Mongolian horse, Sanhe horse and thoroughbreds were genotyped using PCR-SSCP. The relative gene expression level of TYRP1 in the skin tissues among different coat color Mongolian horses was determined using quantitative real-time PCR. The association of the TYRP1 polymorphisms with coat color was analyzed. A missense mutation (C189T) in exon 2 of TYRP1 was detected in the Mongolian horse, resulting in two genotypes: CC and CT. The TT genotype was not observed in these Mongolian horses. Allele C was found to be the predominant allele in black, bay, and chestnut horses. The results showed the TYRP1 gene polymorphism to be closely associated with dark coat color (P=2.3×10−6). The expression level of the TYRP1 gene was the highest in the chestnut skin tissues and the lowest in the gray skin tissues of Mongolian horses. These results suggest that the allele and expression of the TYRP1 gene are associated with coat color and colored coat formation in Mongolian horses. This is the first report of the association of the TYRP1 gene polymorphism with coat color in the Mongolian horse.