A genome-wide SNP-association study confirms a sequence variant (g.66493737C>T) in the equine myostatin (MSTN) gene as the most powerful predictor of optimum racing distance for Thoroughbred racehorses.
Abstract: Thoroughbred horses have been selected for traits contributing to speed and stamina for centuries. It is widely recognized that inherited variation in physical and physiological characteristics is responsible for variation in individual aptitude for race distance, and that muscle phenotypes in particular are important. Results: A genome-wide SNP-association study for optimum racing distance was performed using the EquineSNP50 Bead Chip genotyping array in a cohort of n = 118 elite Thoroughbred racehorses divergent for race distance aptitude. In a cohort-based association test we evaluated genotypic variation at 40,977 SNPs between horses suited to short distance (≤ 8 f) and middle-long distance (> 8 f) races. The most significant SNP was located on chromosome 18: BIEC2-417495 ~690 kb from the gene encoding myostatin (MSTN) [P(unadj.) = 6.96 x 10⁻⁶]. Considering best race distance as a quantitative phenotype, a peak of association on chromosome 18 (chr18:65809482-67545806) comprising eight SNPs encompassing a 1.7 Mb region was observed. Again, similar to the cohort-based analysis, the most significant SNP was BIEC2-417495 (P(unadj.) = 1.61 x 10⁻⁹; P(Bonf.) = 6.58 x 10⁻⁵). In a candidate gene study we have previously reported a SNP (g.66493737C>T) in MSTN associated with best race distance in Thoroughbreds; however, its functional and genome-wide relevance were uncertain. Additional re-sequencing in the flanking regions of the MSTN gene revealed four novel 3' UTR SNPs and a 227 bp SINE insertion polymorphism in the 5' UTR promoter sequence. Linkage disequilibrium was highest between g.66493737C>T and BIEC2-417495 (r² = 0.86). Conclusions: Comparative association tests consistently demonstrated the g.66493737C>T SNP as the superior variant in the prediction of distance aptitude in racehorses (g.66493737C>T, P = 1.02 x 10⁻¹⁰; BIEC2-417495, P(unadj.) = 1.61 x 10⁻⁹). Functional investigations will be required to determine whether this polymorphism affects putative transcription-factor binding and gives rise to variation in gene and protein expression. Nonetheless, this study demonstrates that the g.66493737C>T SNP provides the most powerful genetic marker for prediction of race distance aptitude in Thoroughbreds.
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This research explored the genetic basis for optimum racing distance in Thoroughbred racehorses, identifying a variant in the equine myostatin gene as the strongest indicator.
Study Overview
The researchers conducted a genome-wide SNP (single nucleotide polymorphism) association study on a group of 118 elite Thoroughbred racehorses. Their main area of interest was to identify genetic variations linked to optimum racing distance for different horses.
The horses under study were divided into two categories: those better suited for short distance races (less than or equal to 8 furlongs), and those for middle-long distance races (greater than 8 furlongs). The researchers then analyzed close to 41,000 SNPs across the genomes of these horses to identify any significant genetic variations between the two groups.
Main Findings
The study found that the most significant SNP was located on chromosome 18, approximately 690 kb from the gene encoding myostatin (MSTN), a protein that limits muscle growth and differentiation.
The same region of chromosome 18 also featured a “peak of association” with best racing distance, as indicated by eight SNPs within a 1.7 Mb section. This implies a strong connection between this chromosomal region and the ability to race over certain distances.
Among these SNPs, the one known as BIEC2-417495 stood out as the most significant in both analyses.
Validation of Prior Findings
The researchers previously reported another SNP (g.66493737C>T) in the MSTN gene related to race distance in Thoroughbreds. The current study confirmed that this SNP is indeed important.
Additional sequencing revealed other polymorphisms in the vicinity of the MSTN gene, including a SINE (short interspersed nuclear element) insertion and four novel 3′ UTR (untranslated region) SNPs. However, the original SNP (g.66493737C>T) had the highest linkage disequilibrium with BIEC2-417495, reinforcing its relevance.
Conclusion and Future Directions
The g.66493737C>T SNP in the MSTN gene emerged as the most powerful genetic marker for predicting race distance aptitude in Thoroughbred horses. However, functional studies are necessary to elucidate whether and how this polymorphism affects gene and protein expression, and in turn, racing capacities.
Such research could have significant implications not just for racehorse breeding, but also for our understanding of genetic determinants of athletic performance in other species.
Cite This Article
APA
Hill EW, McGivney BA, Gu J, Whiston R, Machugh DE.
(2010).
A genome-wide SNP-association study confirms a sequence variant (g.66493737C>T) in the equine myostatin (MSTN) gene as the most powerful predictor of optimum racing distance for Thoroughbred racehorses.
BMC Genomics, 11, 552.
https://doi.org/10.1186/1471-2164-11-552
Animal Genomics Laboratory, School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. emmeline.hill@ucd.ie
McGivney, Beatrice A
Gu, Jingjing
Whiston, Ronan
Machugh, David E
MeSH Terms
Animals
Base Pairing / genetics
Base Sequence
Breeding
Chromosomes, Mammalian / genetics
Cohort Studies
DNA, Intergenic / genetics
Genome-Wide Association Study / methods
Haplotypes / genetics
Horses / genetics
Linkage Disequilibrium / genetics
Myostatin / genetics
Phenotype
Polymerase Chain Reaction
Polymorphism, Single Nucleotide / genetics
Sequence Analysis, DNA
Sports
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