Studies Document Genetic Mutation for Parkinson’s Disease
Researchers have discovered that a genetic mutation is responsible for a large percentage of cases of Parkinson's disease in Ashkenazi Jews and North African Arabs, according to two studies published on Thursday in the New England Journal of Medicine, the Los Angeles Times reports (Maugh, Los Angeles Times, 1/26). In the mutation, cells that make the protein dardarin -- which affects brain function -- substitute the amino acid glycine for the amino acid serine, resulting in the tremors and other symptoms that characterize Parkinson's.
According to the Washington Post, the mutated form of the gene LRRK2 was first linked to Parkinson's in 2004 by two groups of researchers. In the first of the new studies, researchers from the Albert Einstein College of Medicine tested the DNA of 120 Ashkenazi Jews with Parkinson's disease and compared it with that of 317 healthy Jews.
They found that more than 18% of Ashkenazi Jews with Parkinson's had the glycine-to-serine error, compared with 1% of healthy Jews. According to the study, about one-third of Jews with the mutation can expect to develop Parkinson's, translating into a 15- to 20-fold risk increase.
A second study led by researchers at the INSERM institute in Paris examined the same mutation in 104 North African Arabs with Parkinson's and compared their DNA with that of 151 healthy Arabs. They found that about 40% of the participants with Parkinson's had the mutation, compared with 3% of healthy participants (Weiss, Washington Post, 1/26).
Susan Bressman, a neurologist at Albert Einstein who led the first study, said, "The importance of genetics (in Parkinson's disease) has been disputed for years and years." She added that the study shows that genetics "is very important" for at least some ethnic groups. Bressman also said the discovery of the gene mutation will allow genetic counseling and early diagnosis of the disease in the affected populations (Los Angeles times, 1/26).
The first study is available online.
The second study also is available online.