Integrating genetics with functional genomics to dissect the aetiopathogenesis of equine exertional rhabdomyolysis

A Warmblood, one of the types of horse predisposed to ER Equine exertional rhabdomyolysis (ER) is a syndrome involving painful, exercise induced episodes of muscle stiffness and acute myonecrosis which can result in renal failure and in severe cases, death. While it is seen in many different species from humans to dogs, horses seem to be particularly predisposed. In thoroughbreds an incidence rate as high as ~5% of the population has been reported. Moreover, other pleasure horses are predisposed to the disease, in particular Warmbloods. It is known that there is a genetic component affecting ER susceptibility (h2=0.34-0.49), meaning it can be passed on from parent to offspring. However, the environment still has an important role in the occurrence of the syndrome with factors such as diet, behaviour and sex playing a role in whether a horse will develop an ER episode. We have shown previously that ER has distinct subgroup phenotypes and that these have a distinct genetic background, with the majority of the genomic markers associated with the disease located in non-coding regions of the genome.