Scientists crack horse genetic code

Twilight, whose DNA was sequenced. Photo courtesy Cornell University.
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Friday, 6 November 2009

An international team of scientists, including researchers from the University of Adelaide, has cracked the genetic code of the horse.

Their findings, published today in the journal Science reveal critical information for mapping horse-related genetic diseases and understanding equine biology.

University of Adelaide genome expert and team member Professor David Adelson says the results will also be used by the racing industry to breed superior horses.

The team, led by animal geneticist Professor Claire Wade from the University of Sydney, sequenced the DNA of a thoroughbred mare named Twilight. The horse is kept at Cornell University in New York State.

"The horse's genome structure reveals remarkable similarities to humans and more than one million genetic differences across a variety of horse breeds," Professor Adelson says.

Better tests for equine genetic diseases, such as disorders of the muscle, therapies for respiratory disease and allergies in horses are already being made possible through increased understanding of equine biology, researchers say.

"There are certain genetic disorders that we know are inherited, but we don't know what's actually causing them. With these results we will be able to identify the cause and develop a genetic test to deal with them," Professor Adelson says.

One unexpected finding from the project was that the wild Mongolian horse (Przewalski's Horse) - once thought to be the ancestor of modern horses - looks very much like another horse breed, even though it has a number of different chromosomes.

Twilight's DNA reveals a genome that is slightly larger than a domestic dog and smaller than the human genome.

Professor Adelson says the horse genome is more "plastic" and changeable than that of humans. "This indicates that the horse DNA sequence is evolving at a more rapid rate."

The team also included researchers from The Broad Institute of MIT and Harvard.

Professor Adelson is Chair of Bioinformatics at the University of Adelaide. He was also part of an international project, completed earlier this year, to crack the genetic code of a female cow, the first mammalian livestock animal in the world to be sequenced.

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