Learning About Parkinson's Disease
What do we know about heredity and Parkinson's disease?
Genes Linked to Early- and Late-Onset Parkinson's
Genes and Environment Most Likely Cause Parkinson's
What determines who gets Parkinson's disease?
Is there a test for hereditary Parkinson's disease?
Current NHGRI Clinical Research on Parkinson's Disease
Additional Resources for Information on Hereditary Parkinson's Disease
(On Online Health Resources page)
What do we know about heredity and Parkinson's disease?
Parkinson's disease is a chronic and progressive disorder of the nervous system that causes tremors and muscular rigidity. It affects about 500,000 to one million people throughout the United States.
There are several types of Parkinson's disease. The two most prevalent are "early-onset" and "late-onset." Early-onset Parkinson's begins before age 50 and accounts for between 5 and 10 percent of all cases. Late-onset Parkinson's starts at age 50 or older and accounts for most cases of the disease.
For many years, researchers debated whether genes or the environment caused Parkinson's. Scientists have linked susceptibility to early-onset Parkinson's to variations in genes on two chromosomes: 4 and 6. Most significant were variations in the "Parkin" gene on chromosome 6, frequently found in families with early-onset Parkinson's. However, researchers continued to think that environmental factors were primarily responsible for late-onset Parkinson's.
Genes Linked to Early- and Late-onset Parkinson's
However, recent research from Duke University Medical Center (November 2001) indicates that heredity plays a part in late-onset Parkinson's as well as early-onset. The Duke study, funded in part the National Institutes of Health (NIH), conducted genetic analyses of blood samples from 174 families with Parkinson's disease.
The study turned up strong evidence that several genes may influence the development of late-onset Parkinson's. The Parkin gene mutation on chromosome 6 (previously linked to early onset Parkinson's Disease) was also detected in families with late-onset Parkinson's. But the strongest linkage to late-onset Parkinson's occurred on chromosome 17, near the Tau gene. This gene has previously been shown to be involved in other degenerative diseases of the nervous system. In addition, variations in genes on chromosomes 5, 8 and 9 were also linked to Parkinson's.
Genes and Environment Most Likely Cause Parkinson's
Inheriting a mutation in a Parkinson's-linked gene does not mean that an individual will develop the disease. In some illnesses, such as Huntington's disease, a single defective gene causes the disease in everyone who inherits it. But in Parkinson's disease, inherited mutations, perhaps in several genes, convey susceptibility. Some people who inherit mutations will get the disease, but others won't.
What determines who gets Parkinson's disease?
Scientists believe that environmental factors trigger the disease in people with a genetic susceptibility. Researchers don't know which environmental factors, but they speculate that pesticide exposure, head injury or hormonal therapy may be triggers.
Is there a test for hereditary Parkinson's disease?
Researchers have made great advances in finding genetic linkages to Parkinson's disease. But there is still no widely available genetic test for the disease.
NHGRI Clinical Research
The ClinicalTrials.gov listing of National Human Genome Research Institute (NHGRI) Parkinson's disease studies currently recruiting participants.