A pack of Seattle geneticists has gone to the dogs and returned with a fascinating ancestral history that sheds light on breed-defining traits of body and behavior -- and may help others investigate diseases shared by humans.
The researchers screened DNA in cheek swabs of 414 dogs from 85 breeds. They found such large genetic differences among breeds that DNA markers alone correctly identified the breed of 409 of the dogs.
Further analysis uncovered the evolution of "at least four distinct breed groupings," the researchers report today in the journal Science. Those range from the most wolflike family -- Asian and African breeds such as the chow chow and Siberian husky -- to a set of newly-bred European hunters, including most hounds, pointers, terriers and retrievers. The DNA even found impostors, breeds thought to be ancient that now look like newcomers, including the pharaoh hound and Norwegian elkhound.
The study proves dog fanciers could use genetics to help trace breeding. But its consequences stretch beyond the collies-and-collars set into the world of human medicine. Researchers already use dogs to hunt for genes involved in epilepsy, cancer and other ailments that plague certain breeds as well as humans, informs oregonlive.com
Researchers found that they could group types of dogs based on these variations. The majority of canines evolved into three clusters of dog variants -- hunters, herders and guard dogs -- largely as a result of breeding programs since the 19th century.
When they compared dog genes to wolf genes, researchers found that a fourth group of ancient dog types split off first. These include the Siberian husky, the chow chow and -- improbably -- the wrinkly faced Chinese Shar-Pei. An improved understanding of dog genetics could help pinpoint risk factors for common diseases, many of which are shared by humans.
"If they could trace things like epilepsy or heart problems, that would be very useful to a breeder because then we would know not to breed that into our dogs," said Keeta Weatherly of Fresno, who breeds miniature dachshunds. "We want our dogs to live long, healthy lives."
The most important work remains to be done, said UC-Davis geneticist Neff.
"We want to identify the specific genes that define a breed, so we can tell you `This dog carries the gene for herding behavior," or "He'll have a Weimaraner coat color." Then we can tell you the genetic legacy of your dog.
"This is only going to get more interesting and more exciting", reports mercurynews.com
According to adn.com the study's main contribution, however, may be in elucidating the genetic basis of both canine and human disease.
"The number-one killer in dogs? Cancer, the same thing we care about in humans," said Elaine Ostrander, a study co-author and a geneticist at the Fred Hutchinson Cancer Research Center. A year ago, Ostrander's group collaborated with Norwegian researchers to map a gene mutation for kidney cancer that appeared in the last 20 generations of German shepherds bred in Norway and the United States.
"Because we had all the pedigree information, we could trace it back 20 generations and say, 'Aha! This is where the problem is,' " Ostrander said.
A mutation in the same gene has been linked to kidney cancer in humans, demonstrating the potential for genetic detective work in dogs to aid both the canines and their human companions.
Dog owners, it seems, were especially helpful to the study. Heidi Parker, the lead author and a graduate student in Ostrander's lab, traveled to dog shows across the country to help solicit DNA from the inner cheek swabs of dogs, and met with an overwhelming response.
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