Genomewide association study reveals a risk locus for equine metabolic syndrome in the Arabian horse.
Authors: S. L. Lewis, H. Holl, C. Streeter, Christian J. Posbergh, B. Schanbacher, N. Place, M. Mallicote, M. Long, S. Brooks
Journal: Journal of animal science
Summary
# Equine Metabolic Syndrome: A Genetic Risk Factor Identified in Arabian Horses Equine metabolic syndrome (EMS), characterised by hyperinsulinaemia and often accompanying severe obesity, remains difficult to diagnose early and lacks targeted treatments beyond dietary and exercise management, making identification of at-risk individuals crucial for prevention of secondary complications such as laminitis. Lewis and colleagues conducted a genome-wide association study in Arabian horses with histories of severe laminitis secondary to EMS, identifying a significant genetic marker (BIEC2-263524) near the FAM174A gene—which is involved in cholesterol regulation—that correlated strongly with elevated insulin levels and laminitis frequency. In a validation cohort, the same marker and a related polymorphism in the FAM174A 3' untranslated region (an 11-guanine allele) remained significantly associated with higher modified insulin-to-glucose ratios and increased body condition scores above 6.5, with near-perfect linkage between the two markers indicating a robust genetic signal. These findings suggest that genetic screening for these specific polymorphisms could identify Arabian horses predisposed to metabolic dysfunction before clinical signs develop, enabling earlier intervention and potentially preventing laminitic episodes. Further investigation into FAM174A function may clarify the biological mechanisms underlying equine metabolic syndrome and could have implications for understanding metabolic disorders across other species.
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Practical Takeaways
- •Genetic screening using BIEC2-263524 or FAM174A markers could identify at-risk Arabian horses before obesity and laminitis develop, allowing early preventative dietary and exercise interventions.
- •Horses carrying the 11-G allele at FAM174A show significantly higher insulin and body condition scores, making them candidates for stricter nutritional management and monitoring programs.
- •This genetic test could help owners and veterinarians make informed breeding decisions and implement targeted metabolic management in genetically predisposed individuals.
Key Findings
- •Genetic marker BIEC2-263524 on chromosome 14 was significantly associated with elevated insulin values (p=0.0024) and increased laminitis frequency (p=9.663×10⁻⁸) in Arabian horses with EMS.
- •The 11-guanine (11-G) allele at FAM174A showed strong correlation with elevated insulin in GWAS population (p=0.0008) and elevated modified insulin-to-glucose ratio in validation population (p=0.0055).
- •Two polymorphisms (BIEC2-263524-C and FAM174A 3' UTR-11G) are in 98% linkage disequilibrium, enabling potential genetic screening for EMS predisposition across a 150-kb haplotype.
- •Identified risk locus near FAM174A gene may play a role in cholesterol homeostasis and metabolic regulation in horses with genetic predisposition to obesity.