Three genes combine for 7 coat types in dogs

WASHINGTON -- From short to shaggy, nearly all the differences in dogs' coat types result from variations in just three genes, according to researchers studying how genes work together.

"What's important for human health is the way we found the genes involved in dog coats and figured out how they work together, rather than the genes themselves," said Dr. Elaine A. Ostrander of the National Human Genome Research Institute.

"We think this approach will help pinpoint multiple genes involved in complex human conditions, such as cancer, heart disease, diabetes and obesity," Ostrander, chief of the cancer genetics branch, said in a statement.

Variations in the DNA — the blueprint for life — in more than 1,000 dogs from 80 breeds were studied by the researchers. The results were then compared to descriptions of various coat types.

The study, published Thursday in the online edition of the journal Science, found that nearly all of the varieties of dog coats can be accounted for by combinations of genes called RSPO2, FGF5 and KRT71.

The findings apply to purebred dogs: "We don't know enough about the genetics of mutts," commented co-author K. Gordon Lark, a biology professor at the University of Utah.

Dogs are descended from wolves and, like wolves, short-haired dogs such as beagles had only the ancestral forms of the three genes, none with variations.

On the other hand, dogs like President Obama's Portuguese Water Dog have variations in all three genes, producing animals with curly hair plus a "mustache" and large eyebrows.

Other findings:

• A variation in the RSPO2 gene produces wire-haired dogs.

• Combine variations in the RSPO2 and KRT71 genes and you get dogs with wiry and curly hair, such as Airedale terriers.

• A change in the FGF5 gene results in longhair breeds such as golden retrievers.

• But long-haired dogs with beards such as the bearded collie have variations in both the FGF5 and RSPO2 genes.

• And combining the FGF5 and KRT71 genes results in curly hair dogs such as Irish water spaniels.

The research was funded by the National Science Foundation, National Institutes of Health, the Nestle Purina Company, the American Kennel Club Canine Health Foundation and the University of California, Davis, Veterinary Genetics Laboratory.