- 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."
09.17.07(Forbes)