Polymorphisms in TNC and COL5A1 genes are associated with risk of superficial digital flexor tendinopathy in National Hunt Thoroughbred racehorses.
Authors: Tully L J, Murphy A M, Smith R K W, Hulin-Curtis S L, Verheyen K L P, Price J S
Journal: Equine veterinary journal
Summary
# Editorial Summary: Genetic Risk Factors for Superficial Digital Flexor Tendinopathy Superficial digital flexor tendon injury represents a significant welfare and economic concern in National Hunt racing, yet individual horses show markedly different susceptibilities to this condition even under similar training regimes. Tully and colleagues conducted a case-control study genotyping 270 affected racehorses and 270 matched controls across seven candidate genes involved in extracellular matrix structure and remodelling, identifying two polymorphisms with significant associations. Horses heterozygous for the TNC BIEC2-696469 variant showed protective effects (odds ratio 0.57 after adjustment for confounders), whilst those homozygous for the COL5A1_01 variant carried nearly threefold increased risk compared to wild-type homozygotes. These findings provide the first genetic evidence that inherent differences in tendon matrix composition and integrity—determined by variants in genes encoding tenascin-C and type V collagen—meaningfully influence SDF tendinopathy susceptibility in Thoroughbreds. Future incorporation of such genetic markers into breeding selection and early risk stratification protocols could enable more targeted preventive management, whilst identifying high-risk individuals for enhanced monitoring and potentially modified training schedules during critical developmental phases.
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Practical Takeaways
- •Genetic screening for TNC and COL5A1 polymorphisms may enable identification of racehorses at elevated risk of SDF tendinopathy before clinical disease develops, allowing targeted preventive management strategies
- •Horses homozygous for the COL5A1 variant allele warrant heightened monitoring and conservative training protocols given their substantially increased tendinopathy risk
- •Genomic testing could complement traditional selection criteria in breeding programs to reduce heritability of SDF tendinopathy susceptibility in Thoroughbred racing populations
Key Findings
- •Heterozygosity for TNC BIEC2-696469 polymorphism reduces SDF tendinopathy risk (OR 0.56, P=0.01), remaining significant after adjustment for age and racing background (OR 0.57, P=0.03)
- •Homozygosity for COL5A1 COL5A1_01 variant allele increases SDF tendinopathy risk nearly 3-fold (OR 2.82, P=0.01), remaining significant after adjustment (OR 2.77, P=0.03)
- •Genetic variants in TNC and COL5A1 genes are associated with susceptibility to SDF tendinopathy in National Hunt Thoroughbred racehorses