SNP-based heritability and genetic architecture of tarsal osteochondrosis in North American Standardbred horses.

The research article looks into the genetic basis and heritability conditions of tarsal osteochondrosis in North American Standardbred horses using a method based on single nucleotide polymorphisms (SNPs).

Research Objective and Methodology

• The study aimed to understand the genetic influences on tarsal osteochondrosis, a common bone problem in Standardbred horses. An estimated range of 17-29% heritability, based on the pedigree data of European Standardbreds and associated trotting breeds, was the starting point of the research.
• Using a high-density genotyping method, the genetic makeup of a population of North American Standardbreds (n = 479) firmly identified with tarsal osteochondrosis was profiled.
• Genome array genotyping data were then converted to approximately 2 million SNPs for further investigation.

Results

• The SNP-based heritability of osteochondrosis in this horse population was explained by 2326 SNPs.
• Most of these SNPs (86.6%) had minor effects, indicating the complex nature of the disease, while a smaller percentage had moderate or significant effects (10%, and 2.9%, respectively).
• Using two different restricted maximum likelihood analysis methods, the heritability was estimated at 0.24 ± 0.16. These estimates were further verified with bootstrapping.

Interpretation and Future Directions

• These heritability estimates were within the previously reported range, suggesting that osteochondrosis is moderately heritable. However, a significant portion of the disease risk is attributed to environmental factors or interactions between the genotype and environment.
• Unearthing specific genes or variants that have the highest impact on disease risk may facilitate early detection of high-risk individuals in the future.