Dog Genome Findings May Benefit Human Health

Scientists studying the genetic background of dogs, which has revealed more than 150 inherited canine disorders resembling specific human diseases, say their work will provide information that can be used to improve human health.

The study, published in the May 21, 2004, issue of Science, has revealed distinct DNA blueprints for each of the 85 varieties of purebreds analyzed. The researchers expect that understanding these genetic relationships will help them uncover the genes responsible for the physical features and behaviors unique to each breed as well as the diseases to which they are commonly susceptible, such as cancer, deafness, blindness, heart disease, and hip dysplasia.

"This study helps us understand the genetic relationship between breeds, a finding that will facilitate our efforts to map disease genes and genes for what are known as complex traits, which result from the interaction of multiple genes,” said Dr. Elaine Ostrander, of the Fred Hutchinson Cancer Research Center (Seattle, WA, USA; www.fhcrc.org), who is head of the dog genome project there.

Since any traits associated with a given breed must result from a shared set of genetic determinants, these genes stand out much more obviously than they would in a population of unrelated, or genetically dissimilar, animals. Since most breeds were developed within the last 300 years, the researchers expect that each distinctive trait has arisen from a small number of genes. These features make it easier to identify a gene or genes responsible for a specific trait.

"There are more than 400 breeds of dog, and each is an isolated breeding population,” remarked Dr. Ostrander. "What that means is that each dog breed is like a little Iceland, an isolated population that allows us to simplify a complicated genetic problem.”

To analyze the similarities and differences among purebred dogs, researchers contracted breed clubs and collected DNA samples from five animals from each of 85 breeds. They then genotyped the DNA, using microsatellite analysis. They found that the DNA sequences of microsatellites from dogs within a breed were much more similar than those among breeds.

They were able to sort the breeds into four groups of genetically similar varieties. One group represents an ancient group of animals with Asian and African origins that includes breeds such as the Alaskan Malamute and Siberian Husky, and shows the closest relationship to the wolf. A second group contains Mastiff-like breeds that share common physical characteristics. A third group includes Shetland and Belgian sheepdogs and Collies. The fourth group includes animals with hunting-associated behaviors.

The researchers are now using the information from their analysis to study specific canine diseases. In addition to cancer, they are studying the genetics of blindness and soon will begin a study on the genetics of obsessive-compulsive disease.

"We could not have done the work without the involvement of pet owners, breeders, and community leaders who support the work we're doing to improve both canine and human health. This is just the way science is supposed to be done,” said Dr. Ostrander.


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Fred Hutchinson Cancer Center