International researchers have identified a gene mutation that "has a favourable effect on harness racing performance" in a study recently published in Nature magazine.
The study's findings show that a "premature stop codon" or mutation of the DMRT3 gene affects the pattern of a horse's gait. The researchers state that, "Our discovery positions DMRT3 in a pivotal role for configuring the spinal circuits controlling stride in vertebrates. The DMRT3 mutation has had a major effect on the diversification of the domestic horse, as the altered gait characteristics of a number of breeds apparently require this mutation."
The gene mutation was identified through comparing 40 Icelandic horses that could pace with 30 that could not.
The study found that Standardbred horses have a high frequency of the DMRT3 mutation allowing the breed "to trot or pace at high speed without breaking into a gallop, the natural gait at high speed for horses." The study explains that Standardbreds are bred to trot or pace, but both have the gene mutation and "[t]hus, the mutation may promote the ability to trot or pace at high speed and genetic modifiers determine the gait to which the horse is best suited."
The study, called "Mutations in DMRT3 affect locomotion in horses and spinal circuit function in mice," was conducted by a team of researchers from Sweden, U.S.A. and Iceland and is available in its entirety here.