TUESDAY, Aug. 30 (HealthDay News) -- A genetic variation that reduces the risk of Parkinson's disease by nearly 20 percent in many populations has been found by an international team of scientists.

They also identified other variants of the same gene -- LRRK2 -- that double the risk of Parkinson's in whites and Asians.

The Genetic Epidemiology of Parkinson's Disease consortium's findings are from a genetic analysis of samples from more than 8,600 Parkinson's patients and almost 7,000 controls across 15 countries on five continents.

The investigation was led by neuroscientists at the Mayo Clinic in Florida, and the findings appear in the Aug. 31 online issue of The Lancet Neurology.

"The idea that Parkinson's disease occurs mostly in a random sporadic fashion is changing," lead investigator Owen Ross said in a Mayo news release. "Our study, one of the largest to date in the study of the genetics of Parkinson's disease, shows that a single gene, LRRK2, harbors both rare and common variants that in turn alter the susceptibility to Parkinson's disease in diverse populations."

These and future genetic findings could eventually help identify people at risk for Parkinson's and possibly lead to new treatments, Ross said.

One expert who was not involved in the study agreed that the findings hold promise.

"The finding that some variants in the LRRK2 gene can reduce the risk of Parkinson's disease is very interesting," said Dr. Andrew Feigin, associate professor of neurology and molecular medicine at the Feinstein Institute for Medical Research in Manhasset, N.Y. "[It] suggests that in addition to there likely being numerous genetic mutations that increase the risk of apparently sporadic disorders, there are also likely to be many genetic variations that reduce risk," he added.

"Though this observation may not lead directly to better treatments for Parkinson's disease, understanding how different genetic mutations in the same gene lead to increased or decreased risk for Parkinson's disease may provide clues to developing novel therapies," Feigin said.

Experts estimate that up to 2 percent of people over the age of 65 develop Parkinson's disease.

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