Using an Inbred Horse Breed in a High Density Genome-Wide Scan for Genetic Risk Factors of Insect Bite Hypersensitivity (IBH).
Authors: Velie Brandon D, Shrestha Merina, Franҫois Liesbeth, Schurink Anouk, Tesfayonas Yohannes G, Stinckens Anneleen, Blott Sarah, Ducro Bart J, Mikko Sofia, Thomas Ruth, Swinburne June E, Sundqvist Marie, Eriksson Susanne, Buys Nadine, Lindgren Gabriella
Journal: PloS one
Summary
# Editorial Summary: Genetic Risk Factors in Insect Bite Hypersensitivity Insect bite hypersensitivity (IBH) represents a significant welfare and performance concern in equine practice, yet its genetic architecture remains poorly understood. Researchers exploited the naturally high inbreeding coefficient of Exmoor ponies—a breed with pronounced IBH prevalence—to conduct a genome-wide association study on 268 animals (110 affected, 170 controls) using the 670K Axiom Equine array, which yielded 452,457 polymorphic SNPs for analysis. Two genomic regions on Chromosome 8 emerged as statistically significant: the first contained the DCC netrin 1 receptor gene, harbouring the study's most significant SNP in an intronic region, whilst the second encompassed five genes (PIGN, KIAA1468, TNFRSF11A, ZCCHC2, and PHLPP1) with multiple associated variants. The DCC gene's involvement aligns with known immune and neurological signalling pathways relevant to hypersensitive reactions, suggesting both type I (allergic) and type IV (cell-mediated) immune mechanisms may be genetically determined. Although validation studies in outbred populations and functional characterisation are essential before implementing genomic selection, these findings offer a tangible foundation for breeding strategies to reduce IBH incidence and potentially inform targeted therapeutic approaches for affected horses.
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Practical Takeaways
- •Genetic testing may eventually identify horses at risk for IBH, enabling targeted breeding decisions to reduce susceptibility in inbred populations like Exmoors
- •Understanding the genetic basis of IBH could lead to earlier intervention strategies and management protocols for affected animals
- •Results are preliminary and require validation in other horse breeds and populations before implementation in practical breeding or management decisions
Key Findings
- •Genome-wide association analysis identified two regions of interest on Chromosome 8 associated with IBH susceptibility
- •Most significant SNP located in intron of DCC netrin 1 receptor gene
- •Second region contains multiple top SNPs spanning PIGN, KIAA1468, TNFRSF11A, ZCCHC2, and PHLPP1 genes
- •Study used 110 cases and 170 controls genotyped on 670K Axiom Equine Genotyping Array with 452,457 SNPs