The DMRT3 gene variant we have identified is permissive for alternative gaits in horses. Traditional three-gaited horses such as most dressage and show jumping horses, draft horses and Thoroughbreds are homozygous for the C-variant (CC). Horses that can perform alternative gaits have the A-variant. Most Icelandic Horses with two copies of the A variant (AA) can perform both pace and the ambling gait tölt while horses with one copy (CA) can only perform tölt.
In several of the other gaited breeds we have tested, most individuals are AA. However, unlike the five-gaited AA Icelandic horses, many of these other breeds are described to only preform an ambling gait. Both training and the genetic background may cause the differences observed in the pattern of locomotion between the different gaited horse breeds.
In a recently released publication by Promerova et al. the worldwide distribution of the DMRT3 mutation has been investigated by screening horses representing 143 breeds. The paper is published in Animal Genetics (link to Animal Genetics) and the paper is free to access until the beginning of April 2014 (link to article).
We will continue our research project on the horse breeds that have both the C and A variants in their population and try to establish the differences in gait among AA, CA and CC (if present) individuals. Such information may be useful for riders and breeders in their choice of horses, as is now possible for Icelandic horse riders through the SynchroGait test. Some Icelandic Horse riders prefer CA horses because there is no pace to “disturb” the training of the basic gaits or the tölt.
It is likely that the A variant is present in all gaited breeds, where it is highly favorable. It is worth noting that pacing is not a desired trait in some horse breeds used for disciplines such as dressage and SynchroGait can thus also be used to eliminate the pacing variant (A) in breeds where the variant does not have a favourable effect.