Equine Genetics Breakthrough: The LY49B Variant
Researchers from the University of Newcastle and the University of Sydney have identified a genetic variant, LY49B, that may be a significant cause of early pregnancy loss in horses. Funded by the AgriFutures Thoroughbred Horses Program, the team is now working to develop a screening test to help breeders manage reproductive expectations.
Key Findings
The gene variant LY49B is considered lethal when present in two copies. No live horse has ever been found with two copies, indicating it causes embryonic death before implantation.
If both the mare and stallion carry one copy of the variant, there is a 25% chance per mating cycle that the embryo will not be viable.
Preliminary screening has revealed a startling prevalence: approximately 50% of Thoroughbreds carry the gene variant.
What’s Next for the Research
The research team is expanding its investigation:
- Confirming prevalence across a broader sample of horses in different regions of Australia, including Queensland, Victoria, New South Wales, and Western Australia.
- Developing a polymerase chain reaction (PCR) test to identify the gene variant in hair or blood samples, which would be more cost-effective than whole genome sequencing.
- Laboratory studies using in vitro fertilization and organoids to investigate the mechanism by which LY49B affects embryo development.
Potential Impact on the Thoroughbred Industry
"If confirmed, the gene variant could account for a 6.25% reduction in per-cycle pregnancy rates at the national herd level."
The development of a screening tool could allow breeders to make informed decisions:
- Avoiding matings between two carriers, or
- Adjusting expectations when both are carriers.
This research may help improve the overall live foal rate, which has remained at 66% for several years in Australia.