(DOG GENETICS) While the physical difference between a great dane and a chihuahua is apparent, the genetic makeup of all dog breeds is pretty much the same. In fact, there are only seven genetic variations that differentiate the thousands of dog breeds living today. — Global Animal
Only seven genes differentiate all dog breeds from one another.

The New York Times, Sindya N. Bhanoo

Spaniels have notably floppy ears, basset hounds have extremely short legs, and St. Bernards are large and big boned. Not to mention Chihuahuas.

Humans have bred dogs to produce tremendous variety. But a new study reports that the physical variance among dog breeds is determined by differences in only about seven genetic regions.

These seven locations in the dog genome explain about 80 percent of the differences in height and weight among breeds, said Carlos Bustamante, a geneticist at Stanford University and one of the study’s authors. The findings, published in Public Library of Science-Biology, are a result of what is the largest genotyping of dogs to date, involving more than 1,000 dogs and 80 breeds.

“We are trying to identify genes that might be important in governing the differences between different dogs,” Dr. Bustamante said. The project was conducted jointly by researchers at Stanford, Cornell University and the National Human Genome Research Institute.

A stronger understanding of dog genomes may shed more light on how genes are involved in disease processes, said Elaine Ostrander, a geneticist at the National Human Genome Research Institute and another author of the study. For instance, it has been hypothesized that osteosarcoma, a type of bone cancer, is a common disease in long-legged breeds, she said.

“Now we have this much deeper lexicon for what genes are really important,” she said, adding that the findings can help researchers investigate the validity of such claims.

Discoveries about dog genomes may in turn help researchers understand the role of genetics in human disease.

“Dogs are still man’s best friend,” she said, “just now in a whole new way.”

More: http://www.nytimes.com/2010/08/17/science/17obdog.html?_r=1&ref=science