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International effort on equine genetics continues making strides

By Kelley Weir & Heidi Jeter

A major Morris Animal Foundation initiative was begun five years ago and is still going strong in advancing the health of horses through genetics research. In 2006, an international team of equine researchers began sequencing and assembling the horse genome, which was completed in early 2007. The collaboration involved scientists at 20 universities around the world. Today, scientists from more than 30 elite academic institutions throughout 14 countries continue to use the initial maps and sequence of the horse genome to identify the molecular basis for diseases that affect horses.

A significant part of this international effort, known as the Equine Consortium for Genetic Research (ECGR), was the largest equine health study in Morris Animal Foundation’s history. Led by Dr. James Mickelson at the University of Minnesota, the goal of the ECGR was to bring together the best equine researchers in the world in a collaborative effort to improve equine health by using the mapped equine genome to determine the location of genes that are either the cause of or are integrally associated with specific disease traits in horses.

Over the past five years, the ECGR has made major inroads in research by funding eight research groups at five North American institutions. Members of the ECGR and scientists all over the world have used single nucleotide polymorphism (SNP) chips—a genetic tool developed with funding from Morris Animal Foundation, the U.S. Department of Agriculture (USDA) and various European partners.

The ECGR funds have been used to study recurrent exertional rhabdomyolysis, commonly known as tying up, in thoroughbreds; lavender foal syndrome in Arabians; extreme lordosis, or swaying of the back, in saddlebreds; dwarfism in miniature horses; and susceptibility to cribbing and immune/infectious diseases in a number of breeds. Other genome researchers are studying osteochondrosis, recurrent airway obstruction, metabolic syndrome, laryngeal paralysis, polysaccharide storage myopathy, cervical stenosis and many other equine conditions.

“The SNP chips allow us to identify those genes that contribute to a genetic disease much more quickly,” Dr. Mickelson explains. “We can then hope to more rapidly find the specific gene and mutation and develop a DNA test to determine a horse’s genetic risk for susceptibility to that particular disease."

For breeders in the industry, the use of genetic tests will allow them to select away from horses with known mutations to improve the overall health and well-being of their breeds. Horse breeders maintain meticulous pedigree records for many horse breeds, some extending back more than 300 years. Deep pedigree records, coupled with excellent health and performance records, provide excellent material for quantitative trait loci studies.

Based on the consortium’s initial success, the University of Minnesota group received a $550,000 grant from the USDA to study the genetic basis for metabolic syndrome, which may predispose horses to a particular form of laminitis. The group is also developing online tools to provide information to the equine industry and help them get involved in research.

“Our researchers are also investigating how the expression of all the genes in the genome responds to complex disease processes such as laminitis and osteoarthritis,” Dr. Mickelson says. “Future studies will now continue this work on many other breeds and many other conditions.”

The ECGR has greatly enhanced the ability of clinical and basic scientists to study genetic processes contributing to high-priority equine diseases and enhance knowledge regarding normal cellular processes governing equine biology, thereby benefiting the entire horse industry.

Overall, probably the biggest success the ECGR has had so far is that it is leading the way in developing and capturing the potential of the equine genome sequence for translational purposes, Dr. Mickelson says. The current equine genome research environment has greatly enhanced the ability of all equine scientists to perform successful research and, in so doing, to identify genes and genetic mechanisms that contribute to susceptibility to diseases both known and unknown.

“We hope to be able to do for the horse what can already be done for human and canine research,” Dr. Mickelson says. “We have teams of researchers in the United States and around the world in position to continue this exciting work. We envision a day in which owners and veterinarians can improve the quality of life of their horses by ensuring that genes that cause highly deleterious conditions are reduced or eliminated.”

Posted by on August 22, 2011.

Categories: Animal health, Horse diseases, Horse health


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