Identification of Y chromosome genetic variations in Chinese indigenous horse breeds

Y chromosome acts as a single nonrecombining unit that is male specific and in effect haploid, thus ensuring the preservation of mutational events as a single haplotype via male lines. In this study, 6 Y chromosome–specific microsatellites (SSR) were tested for the patrilineal genetic variations of 573 male samples from Chinese domestic horse (30 breeds), Przewalski's horse, and donkey. All the 6 loci appeared as a haplotype block in Przewalski's horse and the domestic donkey. There were notable differences, however, at Y chromosome markers between horse and donkey. There were 2 haplotypes of Eca.YA16 in the domestic horse breeds, Haplotype A (Allele A: 156 bp) and Haplotype B (Allele B: 152 bp). Allele A was the common allele among 30 horse breeds, and Allele B was found in 11 horse breeds. This is the first description of a Y chromosome variant for horses. The 2 haplotypes of Y chromosome discovered in the domestic horse breeds in China could be helpful in unveiling their intricate genetic genealogy.