Gene Mutation in Dalmatians Sheds Light on Kidney Stones in Humans

Nov. 8 -- FRIDAY, Nov. 7 (HealthDay News) -- A gene mutation that causes the high levels of uric acid that lead to bladder stones in Dalmatians has been identified by U.S. researchers, who said the finding may provide clues about kidney stones in humans.

Among mammals, only humans, great apes and Dalmatians produce elevated levels of uric acid in their urine and blood. Other dog breeds don't usually produce uric acid.

The team in the School of Veterinary Medicine at the University of California, Davis, analyzed DNA and urine samples from hundreds of dogs and found that mutations in the SLC2A9 gene caused elevated uric acid in Dalmatians. The study was published in the Nov. 7 issue of PLoS Genetics.

In Dalmatians, high uric acid levels result in the formation of bladder stones that often have to be removed surgically. In humans, high levels of uric acid can cause kidney stones, hypertension and gout -- a painful inflammation of the joints.

Humans also carry the SLC2A9 gene, but the exact mechanism that causes high uric acid levels in humans and great apes hasn't been pinpointed. This finding in Dalmatians may help in that research.

"This defect [in Dalmatians] has been reported for nearly a century, and was probably unintentionally introduced as breeders worked to select more distinctive spotting patterns," study author Danika Bannasch, a veterinary geneticist, said in a PLoS Genetics news release.

"This trait can now be removed from the breed by crossing Dalmatians with the normal offspring of the original Dalmatian-pointer breeding that occurred in the early 1970s," Bannasch said. "The result is a healthy dog that looks like a Dalmatian, maintains the Dalmatian breed characteristics and is genetically almost identical."

More information

The U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases has more about gout.

SOURCE: PLoS Genetics, news release, Nov. 6, 2008