(HealthDay News) -- New research shows that only three genes are responsible for all seven types of coats found in purebred dogs.

So, whether a dog is curly-haired like Bo, President Obama's pooch, or long-haired like Lassie, variations of the genes RSPO2, FGF5 and KRT71 are responsible, according to a U.S. National Institutes of Health study published online Aug. 27 in the journal Science. The findings may also point the way toward understanding complex human diseases caused by multiple genes.

In an analysis of 80 domestic breeds that included over 1,000 dogs, it was discovered that RSPO2 is the gene associated with whether or not a dog has a mustache and large eyebrows (known as "furnishings"), FGF5 determines if a dog has short or long fur, and KRT71 is associated with being curly or wavy.

Other findings from the study include:

• Australian terriers and other wire-haired dogs have a variant form of the RSPO2 gene only.
• Airedale terriers and other dogs with wiry and curly hair have variants of the RSPO2 as well as the KRT71 gene.
• Golden retrievers and similar long-haired dogs have a variant form of the FGF5 gene.
• Bearded collies and other long-haired dogs with furnishings have variant forms of FGF5 and RSPO2.
• Portuguese water dogs, like Bo, come in curly and wavy varieties, depending on the form of the KRT71 gene.

The study, conducted at the University of Utah, also found connections between the overall health of a breed and the kind of coat for which it was bred. Dogs bred for a desired trait may become more vulnerable to cancer, immune disorders or other diseases of aging, the researchers noted in a news release from the university.

"Ultimately the most important part of this paper . . . is that we will be able to get glimpses of how major regulatory genes interact with other genes to change the functioning of an animal in a way that does not kill it, but that may eventually compromise its longevity or its functioning as it ages," K. Gordon Lark, a study author and a distinguished professor emeritus of biology at the University of Utah, said in the news release.

More information

The American Kennel Club offers details on the characteristics of different dog breeds.