The field of equine genetics got a huge boost back in 2007 when the first horse genome was successfully sequenced. Now, four years later, what is the state of that novel sequence? Nena Winand, DVM, PhD, a geneticist and assistant professor in the Department of Molecular Medicine at Cornell University in Ithaca, N.Y., and Ernie Bailey, PhD, geneticist and professor of veterinary science at the University of Kentucky’s Gluck Equine Research Center, shed some light on where the genetic sequence is and where it could be going.

Currently, researchers only have the sequence from one horse, Twilight, a Thoroughbred mare produced by a special inbreeding program to try to make this horse homozygous for most traits. "People need to realize that the genome sequence is continuously being edited and improved," said Winand. "It’s a work in progress. As a starting point in studying specific genes, for example, we first compare everything to Twilight’s sequence."

She explained, "If I have a horse in which I want to look at a defect in a certain gene, I clone that gene, sequence that gene (in the horse I’m looking at), and then compare it to Twilight’s sequence."

The genome sequence is a very useful tool to start with, but eventually, researchers would benefit from additional genetic information from different horses, she relayed