Scientists at the University College Dublin, the University of Edinburgh, and the Irish equine genetic testing company Plusvital conducted a study to determine the relationship between inbreeding and the likelihood of a Thoroughbred to make it to the races. The study, titled “Inbreeding depression and the probability of racing in the Thoroughbred horse,” was published June 29, 2022 in the peer-reviewed scientific journal “Proceedings of the Royal Society B.”
The study looked at the genomes of 6,000 Thoroughbreds across Europe and Australia, and demonstrated that for every 10 percent increase in inbreeding, there was a 44 percent lower chance that the horse would make it to the races. In addition, the study pointed to a specific genetic marker which was related to a significant decrease in the likelihood that that horse would make it to the races.
According to the study, that genetic marker (EFNA5) is responsible for encoding the ephrin ligand, which is broadly expressed during tissue development and repair. Among its roles are: neonatal muscle development and regeneration, regulation of cardiomyocytes, skeletal development, fracture repair, and cartilage repair.