Mayo Clinic researchers analyzed clinical and genetic data from 2,692 Parkinson's patients and from 2,652 age- and sex-matched healthy people.
The researchers focused on the gene that encodes a protein called alpha-synuclein or SNCA. Although only a small fraction of Parkinson's patients have SNCA gene mutations, all patients with Parkinson's disease have abnormal amounts of SNCA protein in their brains.
The gene mutation directly causes Parkinson's disease in the rare people unlucky enough to have inherited two identical copies of the mutant gene. More often, a person has a single copy of the gene — which combines with other genetic risk factors to cause Parkinson's disease.
The study's author's estimate that the SNCA gene mutation accounts for 3 percent of the cause of Parkinson's disease.
"The common DNA variants that increase Parkinson's disease risk cause the gene to produce too much alpha-synuclein protein," Demetrius M. Maraganore, M.D., a researcher on the study, wrote in a news release. "Our findings support the development of therapies that reduce alpha-synuclein gene expression. Such therapies have the potential to prevent or delay the onset of Parkinson's disease or to halt or slow its progression."
The researchers report their findings in the Aug. 9 issue of The Journal of the American Medical Association.
SOURCES: Maraganore, D.M. The Journal of the American Medical Association, Aug. 9, 2006; vol 296: pp 661-670. News release, Mayo Clinic.
By Daniel J. DeNoon. Reviewed by Louise Chang, M.D. © 2006, WebMD Inc. All rights reserved