책임운영기관 농촌진흥청 국립축산과학원 (로고)

This study was conducted to analyze the genetic polymorphisms of dopamine receptor D4 (DRD4) in horse breeds and its association with substrate characteristics in Jeju crossbreds (Jeju Horse × Thoroughbred). Polymorphisms in DRD4 are candidate genes associated with temperament in various mammals, including humans. Single nucleotide polymorphism (SNP) G292A in the exon 3 region of the horse DRD4 has a reported association with curiosity and vigilance in thoroughbreds. Sanger sequencing was used to identify polymorphisms of the mutations in DRD4 in three horse breeds. The SNP frequency in Jeju horses was significantly different from the frequency in other breeds. Character evaluation, conducted in the Jeju crossbreds and scored using a temperament test and contact test, revealed a high correlation between each test. Comparison of the polymorphism in the DRD4 of horses and the results of the character evaluation revealed lower scores for all temperaments in horses carrying allele A. Comparison of the SNP of G292A and blood dopamine levels in Jeju crossbreds showed 2.87 times higher levels for the GA type than for the GG type. This study identified an association between DRD4 polymorphism and various test methods for evaluating horse temperament and levels of neurotransmitters. Further research could validate the use of this gene as a genetic marker for character evaluation.