The differences between the silky coat of a cocker spaniel, the wiry hair of a Scottish terrier and the soft curls of a poodle are caused by variations in only three genes, scientists have discovered.

A study of the canine genome has identified the genes that together account for the seven common styles of dog coat, which are present in about 90 percent of pedigree breeds.

As well as offering insights into the evolution of the 209 distinct dog breeds, the findings have implications for understanding human genetics.

The researchers believe that similar techniques should illuminate human traits and diseases with similarly complex genetic roots, such as diabetes and cancer.

“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 Elaine Ostrander, head of cancer genetics at the U.S. National Human Genome Research Institute, who led the study.

“We think this approach will help pinpoint multiple genes involved in complex human conditions such as cancer, heart disease, diabetes and obesity. If we can decipher the genetic basis for a complex trait such as the dog’s coat, we believe that we can do it with complex diseases.”

The study, published in the journal "Science," examined the DNA of more than 1,000 dogs from 80 breeds to search for genetic variations that might contribute to the three key traits that govern coat styles: length, growth pattern and curl.

They found that each of these traits is controlled largely by a single gene that comes in different variants.

The study was conducted using a technique called the genome-wide association study, by which scientists look for genetic variants that are more common among individuals with particular traits. A similar approach has already identified genetic variations linked to more than 500 common diseases and traits in human beings.

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