Professors Jim Mickelson and Stephanie Valberg of the University of Minnesota College of Veterinary Medicine are among the authors of “Genome Sequence, Comparative Analysis, and Population Genetics of the Domestic Horse,” to be published in the November 6 issue of the journal Science. It will be the first published report of the horse genome sequence.
“The sequencing of the equine genome and the publication of this paper in the prestigious journal Science is an important advance for veterinary medicine, as well as human health,” said Trevor Ames, dean of the College of Veterinary Medicine. “Jim Mickelson, Stephanie Valberg, and their team have achieved a major scientific milestone that will benefit animals and people.”
Sequencing of the horse genome began in 2006, building upon a 10-year collaborative effort known as the Horse Genome Project, in which an international team of scientists built preliminary maps of the horse genome and began using genomics tools to address health issues in horses. Mickelson and Valberg played substantial roles in the project, particularly in building the initial maps of the horse genome and demonstrating that the horse genome maps and DNA sequence tools could be used to identify disease-causing mutations. A team of researchers at the Broad Institute, a research collaboration of the Massachusetts Institute of Technology and Harvard University, completed the sequencing and assembly of the horse genome in collaboration with other scientists at 20 universities around the world.
The sequencing of the horse genome allows scientists to better understand genetic aspects of equine physiology and develop new therapies for many diseases in which gene mutations play a major role, such as muscle diseases, orthopedic diseases, recurrent airway disease, metabolic syndrome, colic, laminitis, and immune-mediated diseases. The genome sequence will also provide new insights into behavioral disorders, resistance and susceptibility to infectious diseases, and performance traits.
The $15 million effort to sequence the approximately 2.7 billion DNA base pairs in the horse genome was funded by the National Human Genome Research Institute, one of the National Institutes of Health. The DNA used in the sequencing effort came from Twilight, a Thoroughbred mare at Cornell University College of Veterinary Medicine in Ithaca, N.Y. Researchers obtained the DNA from a small sample of the horse’s blood.

In addition to sequencing the horse genome, researchers produced a map of horse genetic variation using DNA samples from a variety of modern and ancestral breeds. This map will provide scientists with a genome-wide view of genetic variability in horses and help them identify the genetic contributions to physical and behavioral differences between breeds, as well as to disease susceptibility.
The research could also have implications for human health, as there are more than 80 known genetic conditions in horses that are genetically similar to disorders seen in humans, including musculoskeletal, neuromuscular, and respiratory diseases. Comparing horse and human genomes will help medical researchers learn more about the human genome and serve as a tool for veterinary researchers to better understand the disease that affect horses. Valberg, Mickelson, and assistant professor Molly McCue are currently using the horse genome sequence to study inherited musculoskeletal, neuromuscular, and metabolic disease in a number of horse breeds.