Last year, The Horse reported that scientists had discovered a single gene mutation that was responsible for the lateral ambling/pacing gaits of gaited breed horses such as Saddlebreds, Icelandics, and Standardbreds.

But new research has revealed that the same mutation could actually be responsible for success in trot racing, too. Despite the irony, it appears that this DMRT3-gene mutation, called the Gait Keeper gene, is associated with better performance at harness tracks.

“It seems that besides enabling ambling and pacing, this Gait Keeper gene seems to also inhibit transition from the trot to the gallop,” said Leif Andersson, PhD, researcher at Uppsala University and the Swedish University of Agricultural Sciences. Maintaining a trot at high speeds without breaking into a gallop is a critical component of harness racing.

“We’ve already seen that Icelandic horses that are homozygous for the Gait Keeper mutation (meaning they have inherited the mutation from both parents and, thus, have two copies) are worse in the gallop than Icelandics that only carry one copy of the mutation,” Andersson said. “So we think that the Gait Keeper promotes the trot in favor of the gallop.”

Andersson and colleagues investigated breeding and performance records of two breeds of trot-racing horses—the Standardbred and the Nordic Trotter (a heavier, draft-type trotting horse). They also analyzed these breeds’ DNA, with birth dates going back to 1950.

They found