Scientists are gaining unexpected insights into how genes influence the movement of horses as analysis techniques improve, a prominent equine geneticist says.
Dr Gus Cothran, a clinical professor in the Department of Veterinary Integrative Biosciences at Texas A&M University, was commenting after a recent study revealed that the smooth movement seen in gaited breeds is caused by a genetic mutation that can be found across the world.
The paper, “Worldwide frequency distribution of the ‘Gait keeper’ mutation in the DMRT3 gene”, was published this week in the journal, Animal Genetics. Cothran was one of the authors.
Now that we have the genetic tools with enough power, we are beginning to find unexpected insights into how genes influence movement,” Cothran said.
Dr Leif Andersson, a co-author and also based at the Texas university, said: “We have previously demonstrated that a single mutation in the DMRT3 gene has a large impact on gaitedness in horses, and it was therefore named ‘Gait keeper’.
“This gene codes for a protein in a specific subset of neurons in the spinal cord that coordinates the movements of the animal’s legs. The mutated version of the gene causes a truncation of the DMRT3 protein – a genetic ‘mistake’ that allows horses to pace and amble.
The research showed that the mutation arose only once and then spread across the world via positive selection, Andersson said. In other words, early humans probably noticed that some horses had the ability to move in unique ways, and they then selected those horses for breeding, most likely because they offered a smoother, more comfortable ride, called a “running walk” in some breeds.
Horse breeds that are known to perform these so-called ambling gaits are referred to as “gaited”, and the researchers found that the mutated version of the gene is common in these breeds.
They analyzed genes of 4396 horses from 141 breeds and found that the mutation is spread across Eurasia from Japan to the British Isles, in Iceland, in South and North America, and in breeds from South Africa.
“During such ambling gaits the horse has at least one foot on the ground, which means that the vertical movement of the rider is minimal,” Andersson explained.
“For instance, Paso Fino is a breed from Latin America in which the frequency of the ‘Gait keeper’ mutation is nearly 100 percent. It is claimed that the Paso Fino gait is so smooth that you can have a glass of wine in your hand without letting it spill!”
Cothran said he and Andersson were hoping to continue the work with the goal of understanding how other genes can influence the basic gait pattern inferred by DMRT3.”