Targets of selection in the Thoroughbred genome contain exercise-relevant gene SNPs associated with elite racecourse performance.
Athletic performance is influenced by a complex interplay among the environment and a suite of genes, which contributes to system-wide structure and function. In a panel of elite and non-elite Thoroughbred horses (n=148), we genotyped 68 SNPs in 17 putative exercise-relevant genes chosen from a genome scan for selection. We performed a series of case-control and quantitative association tests for relationships with racecourse performance. Thirteen SNPs in nine genes were significantly (P<0.05) associated with a performance phenotype. We selected five SNPs in four genes (ACSS1, ACN9, COX4I1, PDK4) for validation in an independent sample set of elite and non-elite Thoroughbreds (n=130). Two SNPs in the PDK4 gene were validated (P<0.01) for associations with elite racing performance. When all samples were considered together (n=278), the PDK4_ 38973231 SNP was strongly associated (P<0.0005) with elite racing performance. Individuals with the A:A and A:G genotypes had a 16.2-16.6 lb advantage over G:G individuals in terms of handicap rating. Re-sequencing of the PDK4 gene and further genotyping will be required to identify the causative variant that is likely influencing exercise-induced variation in expression of the gene. Notwithstanding, this information may be employed as a marker for the selection of racehorses with the genetic potential for superior racing ability.
Animal Genomics Laboratory, UCD School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. emmeline.hill@ucd.ie
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Hill
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Gu
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McGivney
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MacHugh
D000818:Animals; D016022:Case-Control Studies; D016678:Genome; D006736:Horses / Q000235:genetics* / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000502:physiology; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci