Gene makes racing dogs fast, study finds

WASHINGTON (Reuters) - A gene that helps control muscle development makes all the difference between an elite racing dog and a freak that is put down at birth, scientists reported on Tuesday.

Racing whippets that carried one copy of the mutated gene were among the fastest runners, but those that carried two copies became unattractively bulky and were usually destroyed by breeders, the researchers said.

The next step may be to look for this gene in human athletes to see if it helps explain what makes some competitors excel, said Dr. Elaine Ostrander of the National Human Genome Research Institute, who led the study.

The gene controls a muscle protein called myostatin.

"Our work is the first to link athletic performance to a mutation in the myostatin gene and could have implications for competitive sports in dogs, horses and possibly even humans," Ostrander said.

Ostrander's team has been studying dogs to find the genes for various traits and just last month reported that a gene called IGF1 was responsible for making small dogs small.

They believe this has implications for differences in human size, as well.

While studying whippets, a small, very thin racing breed, they noticed ones that were big and bulky called "bully" whippets.

"They were very, very heavily muscled," Ostrander said. "We were really struck by their remarkable physical appearance."

But breeders do not like them. "The bottom line is, these dogs are not given a chance. When they are born, breeders in this community will describe their appearance as grotesque," she said. Such whippets are usually put down immediately.

The dogs resembled a breed of Belgian blue cattle and certain pigs, and Ostrander's team knew that in livestock this muscling came from a mutation in the myostatin gene.

"The same turns out to be true in whippets," she said.

GORGEOUS DOGS

Ostrander's team then looked at the parents of the mutant whippets. "They were absolutely gorgeous dogs," she said.

Well-muscled and sleek, they lacked the anorexic appearance of most racing whippets, Ostrander said. It turned out the parents each had just one copy of the mutated genes, while their "bully" offspring carried two copies.

When they learned one of these parents was called "Fast Eddie," Ostrander's team knew what to look for next.

"We wanted to know whether or not this was something that could explain racing speed," she said. So her team visited a dog track and got DNA samples from the dogs.

Racing whippets are classified as A, B, C or D, with A racers being the fastest, Ostrander said.

They found the mutation in 12 of 41 dogs graded A or B racers, and in just one of the 43 dogs in the slowest racing grades, the researchers report in the Public Library of Science journal PLoS Genetics.

The gene, called MSTN, affects "fast-twitch" muscle, which is linked to sprinting ability.

Tests of greyhounds, close relatives of whippets, did not find the gene, and Ostrander noted that in cattle with the mutation the lungs are abnormally small.

She believes the gene may affect lung size and thus stamina, which would not matter for whippets, which run a short course. But this would be devastating to a greyhound bred to run longer distances.

Checks of other dog breeds such as Rottweilers, bulldogs and bull terriers found no evidence of the mutation.