Identification of genes with nonsynonymous SNP in Jeju horse by whole-genome resequencing reveals a functional role for immune response

Jeju horse (Natural Monument number 347) is a breed of horse that has experienced long-term isolation and domestication in Jeju Island, South Korea. We evaluated genetic features of this breed, including SNP, by whole-genome resequencing using an Illumina HiSeq 2000. A total of 5,986,852 SNP were identified in 4 Jeju horses and were divided into homozygous and heterozygous SNP (2,357,099 and 3,629,753 SNP, respectively). It revealed that 63.8% of these SNP resided in intergenic regions. Immune response genes with nonsynonymous SNP were overrepresented in Jeju horses as evidenced by Gene Ontology clustering. Among these genes, Toll-like receptors (TLR) are highly enriched. Comparing TLR genes between Jeju horses and the Przewalski’s horse, TLR2 and TLR4 genes showed “possibly damaging” mutations in several regions by analysis with PolyPhen-2. These results provide a framework for further genetic studies in Jeju horse by domestication. Furthermore, research on functions of SNP-associated genes would aid in understanding the molecular genetic variation of horse breeds.