Polymorphism identification, RH mapping, and association analysis with the anxiety trait of the equine serotonin transporter (SLC6A4) gene

Equine anxiety trait is considered an important temperament in various situations, including riding, training, and daily care. This study examined the polymorphism of the equine serotonin transporter (SLC6A4) gene as a candidate genetic element influencing equine anxiety trait. The sequence of the coding region of this gene was highly homologous with those of other mammals, and four single nucleotide polymorphisms were found by comparing the sequences of ten genetically unrelated thoroughbred horses. Radiation hybrid mapping revealed that this gene was located 26.92 cR from neurofibromin 1 on ECA 11. Using two-year-old thoroughbred horses (n=67), the association of these polymorphisms with the anxiety trait was examined, but no significant association was identified between each haplotype of the serotonin transporter gene and the anxiety score.