MONDAY, Sept. 17, 2007 (HealthDay News) -- People who carry a certain gene mutation appear to have a greater risk for getting Parkinson's disease and for getting it at a relatively early age, new research suggests.
The study authors also found that because Ashkenazi Jews -- those with an Eastern European background-- are more likely to carry this gene mutation, this population may run an even higher risk for the disease. An estimated 90 percent of American Jews are of Ashkenazi lineage.
Study lead author Lorraine N. Clark, a researcher at Columbia University, described her team's findings as "unique and different."
"We specifically compared patients who had an early onset Parkinson's before age 50 with patients who had a later onset after age 50, and also with patients with and without Jewish ancestry," she said. "And we showed that mutations are twice as common among early onset Parkinson's and also that they're more frequent among patients with Jewish ancestry."
Clark serves as an assistant professor in the department of clinical pathology with the Taub Institute for Research on Alzheimer's Disease and the Aging Brain, as well as the Center for Human Genetics, both at Columbia University.
The findings are published in the Sept. 18 issue of the journal Neurology.
Parkinson's disease is a brain disorder that affects 1.5 million Americans, according to National Parkinson Foundation estimates. Approximately 60,000 news cases occur each year, striking men and women equally, usually over the age of 65.
The disease is characterized by widespread damage to dopamine-producing nerve cells, impeding their ability to regulate body movement and muscle control. Key signs of the disease include tremors, stiffness, balance problems, and slowness of movement. Patients may also experience difficulty with speech and depression. There is no known cure.
To explore potential genetic underpinnings to the onset of Parkinson's, Clark and her colleagues decided to focus on the GBA gene. Mutations of this gene have already been identified as the cause of Gaucher disease, a rare fat-storage disorder that disrupts spleen and brain function.
Gaucher's and Parkinson's have some links, the study authors noted. In some cases, Gaucher's patients have a family history of Parkinson's, while others actually develop neurological features of Parkinson's. It is also one of the most prevalent genetic illnesses among Ashkenazi Jews.
For the new study, the researchers conducted a sequencing analysis of the GBA gene among 278 Parkinson's patients, 178 of who were of Jewish ancestry dating back to all four grandparents. A similar analysis was done among 179 men and women without Parkinson's.
Clark and her team found that 14 percent of the Parkinson's patients had GBA mutations, compared to just 5 percent of the healthy patients. And, while GBA mutations were found among 22 percent of Parkinson's patients who were diagnosed with their illness before the age of 50, only 10 percent of patients diagnosed after 50 had such abnormalities.
Teasing out information on Jewish patients, the researchers found that while nearly 17 percent of Jewish Parkinson's patients had GBA mutations, the figure was 8 percent among non-Jewish Parkinson's patients.
Clark called the study findings preliminary, and she cautioned that it remains unclear whether a single GBA mutation is a cause of Parkinson's or merely a part of a larger puzzle.
Still, she believes the findings could prove helpful in opening up new avenues of research into the disease.
"This is a gene we hadn't really thought about before," she said. "And it implicates new pathways that might be important in the pathogenesis of Parkinson's disease which could lead to the development of new treatment strategies. I do think, however, that further studies are needed in larger patient populations before we could use this work in diagnostic testing and counseling."
Robin Elliott, executive director of the Parkinson's Disease Foundation in New York City, called the new research "very interesting and very worthwhile, solid work in one of the most fruitful areas of Parkinson's research.
"Genetics and the study of genetics has been one of the most exciting areas of Parkinson's in the last 10 years," he said. "In 1996, we had not a single gene associated with the disease, and now it's up to 12 or 13. So, this is a very important study that pushes the science even further, and gives us the basis for more work."
More information
To learn more, visit the Parkinson's Disease Foundation.
