Jim Mickelson and Stephanie Valberg

Feed Loader, U's College of Veterinary Medicine

U pair helps decode the horse genome

  • Article by: JENNA ROSS
  • Star Tribune
  • November 9, 2009 - 11:28 AM

More than a decade ago, two University of Minnesota professors thought the idea of decoding a horse's DNA was "a pipe dream."

Today, it's a paper published in the journal Science.

Profs. Jim Mickelson and Stephanie Valberg are two authors of that study and part of an international team that has spent years investigating, mapping and now sequencing the genome of the domestic horse.

The discovery is being celebrated by a scientific community that says it could change how diseases in both horses and humans are diagnosed and treated.

It already has, the professors say.

Scientists released a draft sequence of the horse genome in 2007, and researchers began using it immediately, Valberg said.

Without the sequence, it had taken the researchers four years to find the genetic basis for a disease fatal in foals called glycogen branching enzyme deficiency.

With the sequence, they tracked down the cause of another affliction, a painful muscle cramping called "tying-up disease," in six months to a year.

Having a complete, detailed picture against which researchers can compare "greatly speeds up our ability to identify genes that can cause disease," Mickelson said.

The study reported that a horse's DNA sequence is strikingly similar to a human's. "Indeed, 17 [of the 33] horse chromosomes (53 percent) comprise material from a similar human chromosome (in the dog, it is 29 percent)," it says. So discoveries in one species can have implications for the other.

Physicians have been calling the U researchers about their work with "tying-up disease," thinking that they might be able to identify an analogous genetic mutation in people with similar symptoms.

Mickelson and Valberg, both in the U's College of Veterinary Medicine, have been involved since the beginning of what's known as the Horse Genome Project.

More recently, a team of researchers at the Broad Institute -- a partnership between the Massachusetts Institute of Technology and Harvard University -- completed the sequencing of the horse genome.

The Horse Genome Project started its mapping from scratch, gradually becoming more complete. Mickelson compared it to Google Maps:

"The first level is a very low resolution of what the chromosomes look like," he said. "Now they're down to the absolute highest resolution you can get."

Scientists figured out the human genome years ago. They've also sequenced the genomes of about two dozen mammals, including the rat, mouse and sheep. Also this week, researchers announced they had the rough sequence of a domestic pig.

"The pigs are where we were at two years ago," said Mickelson, who then laughed. "Not that there's any competition. It's purely fact."

Jenna Ross • 612-673-7168

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