31 August 2009

Three Genes Determine The Nature of a Dog's Coat

How did the dog get its coat? Kipling never pondered that question — he was more concerned with how the leopard got its spots, among other things — but scientists have. And the answer, they report in Science, lies in just three genes.

Edouard Cadieu and Elaine A. Ostrander of the National Human Genome Research Institute, part of the National Institutes of Health, and colleagues looked at the genetic differences within single breeds that have more than one coat type. Purebred dogs are particularly suited for this kind of study, Dr. Ostrander said, because they have been selectively bred to segregate traits — there are long- and short-haired dachshunds, for example.

The researchers then used that information to look at a large dataset of genetic information from about 900 dogs representing 80 breeds. They were able to identify mutations at specific points, or loci, on three genes linked to fur length, curliness and growth pattern (bushy eyebrows, beards and other features that dog breeders refer to as furnishings).

Then they looked at these three loci, on the genes of another 662 dogs representing 108 breeds — from fluffy Old English sheepdogs to short-haired pugs. They found that the presence of the mutations or not, in various combinations, accounted for the variation in coat in 95 percent of the breeds. Only a few breeds, including Afghan hounds, have coats that can’t be explained by these genes.

There’s a certain elegance to the findings, Dr. Ostrander said. “We look at so much of the complexity in the world around us and say, Oh gosh, the underlying genetics must be so complicated,” she said. “But we’re beginning to feel that in fact nature is simple.”

The eventual goal, Dr. Ostrander said, is to use the same kind of sampling and comparison techniques to uncover how genetic variations combine to cause human diseases.

[Source: NYTimes.com]