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

This study aimed to understand the role of the equine serotonin transporter (SLC6A4) gene in influencing anxiety traits in horses, which is a crucial aspect of their temperament. Despite identifying four polymorphisms (variations) in the gene, the researchers found no significant correlation between each gene variation and the animals’ anxiety scores.

Study Objective and Methodology

• The primary objective of the study was to investigate the role of the equine serotonin transporter (SLC6A4) gene in influencing anxiety traits in horses. Anxiety in horses significantly impacts several situations such as riding, training, and daily care.
• The researchers sought to accomplish this by studying the polymorphism (genetic variation) of the equine serotonin transporter gene.
• The examination involved comparing the coding region sequences of this gene from ten genetically unrelated thoroughbred horses. The sequence of this region was found to be highly identical to those of other mammals.
• During the study, researchers identified four single nucleotide polymorphisms (SNPs) of the serotonin transporter gene. SNPs are the most common type of genetic variation among horses.

Results and Conclusion

• Radiation hybrid mapping, a commonly used technique to locate the position of a gene, revealed that the serotonin transporter gene was located 26.92 centimorgan (cR), a unit of genetic recombination frequency, away from the neurofibromin 1 gene on the eleventh horse chromosome (ECA 11).
• The researchers then conducted an association analysis to explore the relationship between these genetic variations and anxiety in horses. For this, they used two-year-old thoroughbred horses (67 in number).
• Unfortunately, no significant association could be established between each haplotype (a combination of alleles at adjacent locations on a chromosome that are transmitted together) of the serotonin transporter gene and the anxiety score in horses.
• The study concluded that while the serotonin transporter gene displayed variation, this did not notably influence the anxiety traits in the studied population of horses.