Key genes linked to successful racehorses identified by international team

A set of genes linked to successful racehorses has been identified by an international research team, headed up by University College Dublin professor Emmeline Hill.

Scientists from Asia, Europe, North America and Irish equine science company Plusvital compared the genomes of thoroughbred, Arabian and Mongolian racehorses to horses bred for other sports, and were able to identify a set of genes that play a significant role in muscle, metabolism and neurobiology.

These genes were found to be different in racing horses and were common to all racing breeds compared to those from non-racing breeds.

Hill, chief science officer at Plusvital, said: “Since the discovery of the ‘Speed Gene’ in 2009, we have generated genetic data for thousands of thoroughbreds and horses from other breeds.

“This is the first time this set of genes has been linked to the success of racing breeds. Two of the genes were previously identified for performance in thoroughbreds and Arabians, but the approach
we took was to ask what genes were common to all racing breeds and different from non-racing breeds.

“The very large number of horse breeds developed over the last hundreds of years all over the world have been carefully shaped by selective breeding for different traits desired by breeders. This has led to tall horses, small horses, powerful draft horses, useful riding horses, and fast racing horses.

“We have discovered a set of genes common to racing horses, but not all horses within a racing breed have the advantageous gene version, so these findings will be useful to identify the most suitable individuals within a breed for racing or for breeding.”

Co-author UCD professor David MacHugh added: “Although racing is a multifactorial trait, with management and training having a considerable influence on the success of a racehorse, this study provides good evidence for major-effect genes shaping the racing trait in horse populations.”

Published in Communications Biology, an open access journal from Nature, the research included a collection of hair samples from 100 horses owned by the Ajnai Sharga racing team at their breeding farm in Khentii province, Mongolia, the birthplace of Genghis Khan.

The scientists used the DNA from the Mongolian horses alongside thoroughbreds and Arabians to compare their genomes with 21 other non-racing breeds - including Clydesdale, Connemaras, Hanoverian, Morgan, Norwegian Fjord, Shetland, Shire - and identified seven essential genes for racing.

A set of genes linked to successful racehorses has been identifiedCredit: Edward Whitaker

Among the top genes was NTM, which functions in brain development and influences learning and memory. This gene was selected during the horse domestication process, and in thoroughbreds influences whether a horse ever races.

MacHugh said: "This finding suggests that equine neurological systems perturbed by natural and artificial selection associated with domestication may overlap with adaptive traits that are required for racing."

Dr Haige Han, another project collaborator and first author of the paper, said: "Testing these variants in new sets of hundreds of horses from racing and non-racing breeds identified seven essential genes for racing. These genes have roles in muscle, metabolism and neurobiological functions, and are central to racing ability among horse breeds.”

The researchers used gene expression data from skeletal muscle from thoroughbreds to investigate if the genes they had identified were involved in the muscle response to exercise and training.

Hill said: "By integrating these two different data sets we fine-tuned the list of racing genes to those that were most biologically relevant to racing. One of these genes was MYLK2, which is required for muscle contraction. In humans, MYLK2 is associated with exercise-induced muscle damage."

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