Genetic risk factors for osteochondrosis in various horse breeds.
Authors: Naccache F, Metzger J, Distl O
Journal: Equine veterinary journal
Summary
# Editorial Summary Osteochondrosis (OC) and its progression to osteochondrosis dissecans (OCD) represent a significant economic and welfare burden in equine practice, yet genetic contributions to disease susceptibility remain incompletely understood across different breeds. Naccache and colleagues conducted a comprehensive review of quantitative and molecular genetic studies, synthesising findings from genome-wide association scans utilising SNP50 and SNP70 chip technology across multiple breeds including Thoroughbreds, Standardbreds, trotters, and warmbloods. Heritability estimates varied substantially by breed and anatomical site: hock OC showed moderate-to-high heritability in Hanoverians and Norwegian trotters (0.29–0.46) but minimal genetic variation in Thoroughbreds, suggesting breed-specific genetic architectures. Four chromosomal regions (ECA 3, 14, 27, and 29) emerged as consistent OC risk loci across validation studies, with a particularly strong association identified on ECA 3 upstream of the LCORL gene and hock-OCD phenotypes. For practitioners, these findings underscore that genetic predisposition to OC is breed-dependent and site-specific, warranting selective breeding strategies tailored to individual populations, whilst emerging functional genomic approaches—including gene expression profiling and next-generation sequencing—may eventually enable molecular prediction and targeted intervention to reduce disease incidence.
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Practical Takeaways
- •Genetic predisposition to osteochondrosis varies significantly by breed; breeding selection based on identified genetic markers may help reduce disease incidence in high-risk populations
- •The LCORL gene region on ECA3 represents a validated genetic risk marker for hock-OCD and could be incorporated into genetic testing panels for breeding decisions
- •Understanding breed-specific heritabilities helps practitioners set realistic expectations for OC prevention through management versus genetics in different horse populations
Key Findings
- •Heritability for hock OC ranges from 0.29-0.46 in Hanoverian warmblood and Norwegian trotters, but is very low in Thoroughbreds
- •Genome-wide scans identified OC risk loci on horse chromosomes 3, 14, 27, and 29, with strongest association for hock-OCD on ECA3 upstream of the LCORL gene
- •SNP validation studies in Spanish Purebred and Hanoverian warmblood horses confirmed OC risk loci across multiple breeds
- •Gene expression and RNA sequencing approaches offer potential to identify candidate genes and clarify pathophysiological mechanisms underlying OC development