Genetic Mutation May Explain Many Parkinson's Disease Cases
Oct. 5, 2000 -- Parkinson's is not a fatal disease, but it can have an increasingly devastating effect on a person's life, or on the people that take care of the patient. It's not just that the symptoms limit mobility and the medications have worrisome side effects, but also that no one can answer the question, "Why?" When a younger person like Michael J. Fox gets the disease, the burden magnifies, because the individual may have to quit working.
Some answers about the causes may be forthcoming, according to genetics researchers from Duke University. Mutations of the so-called Parkin gene are more common in people with both late- and early-onset variations of the disease, they said recently at the annual meeting of the American Society for Human Genetics in Philadelphia.
This gene already has been considered to be a culprit in the early-onset version of the disease. In 1998, Japanese researchers reported that such early-onset patients were more likely to have a mutation of this particular gene. Now, the results of the current research show a specific mutation of this gene that also may play a role in patients who get Parkinson's disease when they are older.
"This is one of the first clear findings that Parkinson's disease clearly has a genetic component to it," lead researcher Jeffery Vance, MD, PhD, tells WebMD.
The researchers enrolled more than 800 patients from 175 families with a history of Parkinson's disease; the average age of onset of the disease was 60 years. The investigators found that families had a "significant genetic effect" when more than one family member had developed the disease before the age of 40.
By doing a genetic screen, Vance and his colleagues discovered a pattern among the study participants on chromosome 6, where the Parkin gene is located. The pattern existed regardless of age of onset, says Vance, the director of the Genomics Research Laboratories at the Center for Human Genetics at Duke University in Durham, N.C. Still, while higher than chance, the rate at which this mutation was found was not extraordinarily high, found in 2 or 3% of late-onset patients, and in 6% of the total families, he says.
"When patients are diagnosed with Parkinson's disease, they should mention to their physician any other family members that have the disease," Vance tells WebMD. In the future, if further research yields similar findings, some type of genetic screening may be used for diagnostic and prognostic purposes, he says.
"Research on the genetics of Parkinson's disease is exactly on the right track, because the goal is not just to treat this condition, but to prevent it," Richard A. Levinson, MD, DPA, tells WebMD. "Approximately 1 million to 1½ million people in the U.S. live with Parkinson's disease, and the numbers will increase as the population ages." Understanding the genetic susceptibility to Parkinson's disease will help researchers understand the disease and develop more effective treatment, says Levinson, who was not involved in the research. He is associate executive director of the American Public Health Association.