Canine-gene research may help lives of humans

What does the huge Alaskan Malamute, arctic sled dog of the frigid northern tundra, have in common with the diminutive Pekinese, pampered lap dog of Chinese nobility? It turns out that they are among the most ancient breeds of dogs, splitting their lineage from the wolf centuries ago.

That was one of the many startling conclusions of the research reported recently in Science magazine by researchers from the Canine Genome Project at the Fred Hutchinson Cancer Research Center in Seattle.

The genetic data showed the Asian spitzes, Shar Pei, Shiba Inu, Akita and Chow Chow were the most genetically distinct and thus the oldest breeds. Also included in this group were the arctic sled dogs, the Siberian Husky and Malamute. And these breeds do resemble each other.

But the other three dogs in this grouping were the Basenji, Saluki and Afghan hound — dogs that neither resemble each other nor come from similar geographic locations. This finding may indicate migration patterns of early humans and dogs during the domestication of the dog. The three Asian lap dogs were the next most distinct breeds, and all the other breeds tested split into a grouping of modern European breeds.

There were some expected findings, as many of the herding dogs grouped together, as did many of the mastiff-related dogs. The Belgium Sheepdog and Belgium Tervuren are considered separate breeds by the American Kennel Club but in Europe are considered varieties of a single breed. These two breeds could not be separated genetically, indicating that the split is too recent to have resulted in sufficient genetic variation.

There were some surprises, too.

Some historically older breeds – the Norwegian elkhound, Pharaoh hound and Ibizan hounds – clustered genetically with the modern European breeds, reflecting some admixture of other genes.

“This work doesn’t address the question of when breeds were actually formed, but rather their genetic relatedness,” said Dr. Elaine Ostrander, a geneticist involved in the project.

While it is interesting to know these dog lineages, and any dog parent is fascinated when considering their pet’s family tree, this still leads one to ask: Why would researchers at the Fred Hutchinson Cancer Research Center care about the evolution of the dog or strive to scientifically differentiate between the breeds?

It turns out the researchers had a serious reason for looking for genetic differences between dog breeds.

For any individual, dog or human, to develop a disease, it takes interplay between environmental factors and genetic factors. It is then of great interest to scientists to be able to look at the underlying genetic factors that lead to the development of specific diseases. It turns out that dogs are a good place to look for these genetic factors.

Dogs are known to suffer from around 350 identified diseases that have been shown to have a genetic basis, and many diseases that dogs get are also seen in humans. Veterinarians and dog breeders know that certain diseases tend to cluster in specific breeds, indicating a genetic component to the development of these diseases.

If scientists can unravel how the genetics contribute to the development of diseases like cancer, heart disease, epilepsy, blindness and deafness, this could provide valuable information of how to prevent and treat those diseases in humans, as well as dogs.

Dogs have been bred for centuries, resulting in specific populations of similar looking dogs bred for specific traits.

Later, with the development of breeds with pedigrees and selective breeding, these populations became closed. That meant that there was less genetic variation within a breed, and this current research was launched to determine the degree of genetic differences between the breeds.

Based on DNA isolated from cheek swabs from 85 breeds, the results were clear cut: the researchers were able to identify sets of genetic markers that were specific to each breed. This gave them the ability to both look at dog evolution and genetically identify the breeds. In other words, with a few exceptions, they could group the boxers with the boxers and the elkhounds with the elkhounds by looking at their genes.

“So if we were looking at a specific disease that is in one breed, we could look at closely related breeds to see if that genetic mutation is in the related breeds, because they may have inherited the same ancient mutation as well,” explained Ostrander. “Once we find the identified disease gene in the dog, we can look to see if this gene or the mutation is important in similar diseases in humans as well.

“Thus we are working to improve companion animal health and human health simultaneously.”

Dog owners can help this research progress. The Canine Genome Project is accepting canine DNA cheek swabs from specific breeds of AKC-registered dogs.

If you are interested in having your purebred dog participate in these studies, send an e-mail to cgp@fhcrc.org and provide your name, your dog’s registered name, your dog’s breed, any diagnosed disease your dog has, the age of your dog and the best way to contact you.

Through the centuries our faithful dogs have been at our sides, guarding our homes, herding our flocks, protecting our food supply from vermin, keeping us warm and giving us their love. Now they are helping us solve the diseases that affect both dogs and humans.