A gene linked with the immune system may play a role in developing Parkinson’s disease, researchers said on Sunday, marking a possible advance in the search for effective treatments.

They said a gene in the human leukocyte antigen region or HLA - which contains a large number of genes related to immune system function - was strongly linked with Parkinson’s disease.

“That means the immune system probably plays a role in your body developing Parkinson’s disease,” said Dr. Cyrus Zabetian of the University of Washington and Veteran’s Administration Puget Sound Health Care System, whose study appears in the journal Nature Genetics.

Zabetian said there had been hints that the immune system may be linked to Parkinson’s disease, a neurodegenerative disease that affects 1 to 2 percent of people over age 65.

“This is the best evidence we’ve seen so far,” Zabetian said in a telephone interview.

The finding came from a large, long-term study of more than 2,000 Parkinson’s disease patients and 2,000 healthy volunteers from clinics in Oregon, Washington, New York and Georgia.

Parkinson’s sufferers have tremors, sluggish movement, muscle stiffness and difficulty with balance.

Researchers looked at clinical, genetic and environmental factors that might contribute to the development and progression of Parkinson’s disease and its complications.

“We found strong evidence that a gene within the HLA region is associated with Parkinson’s disease,” Zabetian said.

HLA genes play an important role in helping the body discern between foreign invaders and the body’s own tissues.

“We don’t know specifically which gene because there is a cluster of genes in that region, but it is the first really strong link that the immune system plays a role,” he said.

That may mean infections, inflammation or an auto-immune response play some role in the development of Parkinson’s disease, Zabetian said.

“What this allows us to do is to hone in on the immune system,” he said.

Although current medical treatments may improve symptoms, none can slow or halt the progression of the disease.

The study was funded in part by the National Institute of Neurological Disorders and Stroke, one of the National Institutes of Health.

SOURCE:  Nature Genetics, online August 15, 2010.