Epsilon Archive for Student Projects

Abstract

A genome-wide association analysis of Icelandic horses has shown that a mutation in DMRT3, doublesex and mab-3 related transcription factor 3 (‘gait keeper’ mutation), has a strong impact on gait pattern. The DMRT3 mutant allele (A) has been found in high frequency in gaited breeds, and breeds used for harness racing, while non-gaited breeds were homozygous for the wild-type allele (C). Icelandic horses have the ability to perform alternate gaits besides the three basic gaits (walk, trot, canter/gallop) such as flying pace and tölt. Homozygosity for the DMRT3 nonsense mutation enables pace and has a positive effect on the quality of tölt (beat quality, speed capacity and suppleness). CA Icelandic horses on the other hand have better scores for walk, trot, canter and gallop. Previously, two border-line significant single nucleotide polymorphisms (SNPs) have been associated with tölt in another genome-wide association study (using breeding values as the phenotype). The aim is to validate the two tentative associations in additional Icelandic horses. In this study we want to confirm the association of two SNP markers, one on Chromosome 13 and one on Chromosome 28 with breeding values (EBVs) for tölt (tölt, slow tölt and direct tölt). We also want to investigate the genotype frequencies in; American Curly, American miniature horse, American Saddlebred, Friesian, Hackney, Morgan, Peruvian Paso, Rocky Mountain and Swedish Warmblood. TaqMan SNP Genotyping Assays was used to genotype the individuals for the SNP markers of interest. The association was confirmed for EBVs on Chromosome 28 (tölt P=0,03*, P=0,03*) and also Chromosome 13 (tölt P=0.009**). Next step is to fine map the confirmed genomic regions.