Researchers Link Gene Mutation to All Gaited Breeds

Researchers Link Gene Mutation to All Gaited Breeds

The researchers’ finding dispels the theory that gaitedness occurred independently in various regions, leading to dozens of gaited/pacing breeds throughout the world.

Photo: Anne M. Eberhardt/The Horse

Did you hear the one about the suave Saddlebred stallion who wanted to impress a herd of mares?

He just ambled on by.

We now know that our suave Saddlebred stallion likely has the “Gait Keeper” gene in his chromosomes.

Recent study results from an international group of researchers indicate that a horse’s ability to have gaits such as ambling and pacing comes down primarily to one particular mutated gene: the so-called Gait Keeper gene.

This Gait Keeper mutation appeared spontaneously in a single ancient domestic horse, ultimately triggering breeding programs to maintain the mutation and develop individual breeds from it, said Leif Andersson, PhD, from Uppsala University and the Swedish University of Agricultural Sciences. The exact time period that the mutation, which occurred in the DMRT3 gene, developed has not been determined, he said.

The researchers’ finding dispels the theory that gaitedness occurred independently in various regions, leading to dozens of gaited/pacing breeds throughout the world, Andersson said. “We can see this because we find exactly the same mutation in the same sequence context in all gaited horses we have tested,” he told The Horse.

In essence, humans probably found the new gaits pleasing and decided to selectively breed for the mutation in certain groups of horses, thereby creating “gaited” breeds, he said. Other genes besides the DMRT3 mutation can contribute to gaitedness, “but no other gene variant than the Gait Keeper mutation has been identified with such a strong effect on the gait,” he added.

In their study, Andersson and his international research team—from Sweden, the U.S., Japan, Germany, Spain, the Czech Republic, Iceland, Norway, and Iran— genotyped more than 4,000 horses worldwide, seeking the Gait Keeper mutation. They found the same mutation across the planet and across breeds. And they found that in the breeds considered “gaited” or “pacing,” the mutation was present in at least 50% of the represented study horses.

The Gait Keeper mutation can be heterozygous—meaning that it occurs in only one of the DMRT3 copies of a horse—or homozygous—meaning it occurs in both copies—and this can explain the difference in gaitedness among horses within a single gaited breed, Andersson said.

“For instance, if you cross two heterozygotes, then 25% of the progeny will have no copy of the mutation (called “wild-type”), and many of these will be difficult or impossible to get ambling," he said. "Half will be heterozygous, and the great majority of these will amble. Then 25% will be homozygous, and they will amble—and many of them will be able to pace as well.”

Genetic testing could help breeders selectively breed homozygous horses for a more certain chance of having offspring capable of ambling and pacing, Andersson said.

The study, "Worldwide frequency distribution of the ‘Gait keeper’ mutation in the DMRT3 gene," was published in Animal Genetics

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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