Aug. 27, 2009— -- Based on new research from the National Institutes of Health, first dog Bo is once, twice, but not quite three times a mutant.
Researchers from the NIH and several universities have shown that variation among the coats of different dog breeds can be traced back to three genes.
Like about half of other Portugese water dogs, Bo possesses two mutant genes that contribute to the appearance of his coat of curly hair. What he lacks is a third mutant gene which would have given him the "furnishings," or a moustache and eyebrows, that are typically seen in dogs with wiry hair. Bo's lack of furnishings means that he has the ancestral form of that gene, matching the patterns found in wolves, according to the research.
"I think he's a perfect example of a Portuguese water dog, and a Portuguese water dog is an outstanding breed." It's an outstanding choice for the first breed," said Elaine A. Ostrander, chief of the cancer genetics branch of the National Human Genome Research Institute, the study's lead author.
She noted that the lack of eyebrows and a moustache was not a hindrance to Bo, a gift to the Obamas from recently deceased Sen. Ted Kennedy, who owned several Portuguese water dogs himself.
"You don't expect Portuguese water dogs to have that," she said of the furnishings. "He looks like a very typical Portuguese water dog."
And Ostrander acknowledged that, "We haven't tested Bo" among the 76 Portuguese water dogs looked at in the study. "If the Obamas would like to contribute, we'd be more than happy to," she said.
By studying dogs' coats -- a trait easily observed by the human eye -- researchers wanted to better understand how the genes affected the coats, leading, they hope, to more specific findings in the genome later on. While the coat gene was initially found in Portuguese water dogs, researchers used genomes from 903 dogs in 80 different breeds to reach their overall conclusions.
Portuguese water dogs were chosen for the study because they have two distinct kinds of coats: some with curly hair, like Bo's, but others with long wavy hair. According to the American Kennel Club, there is no preference among breeders for one of the two coats.
"Because it does come in two coat types, that would, obviously, be a great study breed," said Lisa Peterson, a spokeswoman for the American Kennel Club.
Breeders of Portuguese water dogs are also willing to work with researchers, so, "Bo is probably one of the better-understood breeds, in terms of genetics," said Neale Fretwell, chief geneticist at Gaithersburg, Md.-based Mars Veterinary, a division of Mars Inc., the confectionery and pet food manufacturer. "That's probably good news for Bo, because the genes of his brethren have been well studied."
Fretwell, who was not involved with the research, said that the results of the study match expectations, in that three genes had a large impact.
"It really mirrors what we see in dogs in general," he said. "What gives them their characteristic traits is determined by a small number of genes."
Man's Best Research Partner?
While the three genes accounted for most of the variation, they showed up and combined a bit differently in the different breeds.
"It's not just that you have three phenotypes [observable traits] that are completely independent," Fretwell said.
While 95 percent of dogs sampled had coats that could be explained by the three genes, a few breeds showed that they must be getting some genetic information from elsewhere, so researchers still have a little work to do to explain dogs completely.
"Some of the long-haired breeds don't seem to be sharing these mutations," Fretwell said.
While the study itself may not have immediate benefits, researchers and dog advocates alike are optimistic that this line of inquiry will have benefits down the road.
"There's no direct benefit because coat variation is not a medical issue," Peterson said. "The study itself is wonderful to provide more knowledge to study traits and do more research toward canine and human health."
Ostrander said, "Dogs really give us a tremendous opportunity as geneticists to understand the genetic underpinnings of lots and lots of things that we're interested in. All the same rules, all the same methods, all the same techniques will be the same for diseases as well. They get all the same diseases humans do and the same genes are likely to be involved."
The breeding patterns of dogs -- where they have been selectively bred for specific traits for centuries -- have also been an asset.
"The dog genomes … will lead to some discoveries in some diseases in the future that will enable us to find the cause to diseases that are hard to get to the bottom of in humans," Fretwell said.
"If you find a gene in dogs, oftentimes it has the same function in humans," he said. "The gene function is very well conserved between the species."
"The process that was used to identify these coat variation genes can act as a model for studying complexly inherited disease in animals and in man," said Jerold Bell, clinical associate professor of genetics at Tufts Cummings School of Veterinary Medicine. "Another more specific benefit is that some of these coat variation genes are also linked to specific skin diseases, such as hair follicle tumors and follicular dysplasia."
Additional uses could also be found, said Fretwell, in the cosmetics industry, where hair genetics might prove a useful area of inquiry.
Safer Dog Breeding
While purebred dogs can often suffer from genetic illnesses as a result of inbreeding, genetics research may be able to lessen that problem.
"All the genetic research that's been done now enables responsible breeders to breed healthier dogs," Peterson said.
And that may be more important with time, particularly for dogs like Bo.
While breeders don't discriminate between curly- and wavy-haired Portuguese water dogs, Fretwell speculates that the curly-haired variety may find themselves a more popular variant of the breed.