GenePD
 Frequently Asked Questions (FAQ)

1. Is Parkinson's disease inherited?

2. What is the role of genetics in common forms of PD?

3. If some forms of PD might be inherited and others not, what are some of the non-genetic causes that   might be involved?

4. I heard about a gene for PD in an "Italian Family" from the Contursi region of Italy?  What does this mean for me and my family?

5. Are there other genes known to be involved in PD?

1. Is Parkinson's Disease inherited?
There are a few families that have a form of PD that is clearly inherited. In these families, many people across several generations are found to have PD. These families are very rare but they may help us understand what causes the more common forms of PD that do not have this very strong genetic cause. A gene that causes one such form of PD has been found in a family from Italy.

2. What is the role of genetics in common forms of PD?
The cause of common or Idiopathic Parkinson’s disease is not known. Traditionally, scientists and doctors did not think that PD had a genetic basis. One reason that genes were not thought to be important in PD is that when one identical twin had PD, the other twin usually did not have PD. However, as the twins were followed for longer periods of time and as sensitive brain imaging studies were performed, convincing evidence was found demonstrating that the second twin did show an increased risk for developing PD.

Additional studies have been done to look at whether the parents or the brothers and sisters of persons with PD are at increased risk. These studies also give support to the possible role for genes in the cause of PD.

While the risk to parents and siblings is not overwhelmingly large, it is considerably larger than that seen in the general population. About 16% of the PD patients' parents (one in six) are reported to have had symptoms of PD. Similarly, about 10% of siblings (one in ten) are reported to have PD. On the other hand, the husbands and wives of persons with PD do not have an increased risk and between 1 to 2 percent of them are found to have PD.

The finding of an increased risk to the parents and siblings together with the absence of an increased risk to the husbands and wives of persons with PD gives credibility to the notion that genes may play a significant role in the cause of PD. Nevertheless, most persons with PD will not have any other relatives with the disease and this also gives support for the possibility that some people get the disease for reasons that have nothing to do with genes or inheritance.

3. If some forms of PD might be inherited and others not, what are some of the non-genetic causes that might be involved?
There may be many causes of PD. Some may be genetic and others non-genetic. Some of the non-genetic causes might be things like (1) infections or influenza, (2) exposures to toxic chemicals or pesticides or (3) head trauma or concussion. While the causes of PD are not known, it seems likely that different people may have different causes for their PD.

4. I heard about a gene for PD in an "Italian Family" from the Contursi region of Italy?  What does this mean for me and my family?
One family from Contursi was noted to have many people in several generations who had PD. In this unusual family, the disease is clearly inherited. The gene responsible for the disease was found on chromosome 4 by a team of investigators from the Robert Wood Johnson Medical School in New Jersey and the National Institutes of Health in Bethesda, Maryland. They determined that a gene called "alpha-synuclein" had an error or mutation that caused this form of inherited PD.

However, after studying hundreds of people with PD and even other families with many cases of PD, scientists have found only a few other cases of PD with the alpha-synuclein mutation.

The vast majority of families with several cases of PD do not have the alpha-synuclein mutation and as yet no cases of "sporadic" PD (persons with no family history) have been found to have the alpha-synuclein mutation.

Thus, while the finding of the alpha-synuclein mutation may prove to be important for the understanding of the cause of PD, it does not have a direct role in the cause of the disease outside the few families that have this mutation.

5. Are there other genes known to be involved in PD?
There have been some studies that suggest that other genes causing rare familial forms of PD may exist. These other genes have not yet been identified however. Most of the work to find these genes involves studies of large families with many people who have PD. If you are a member of such a family, your family may be critical in helping to learn the causes of PD. Please consider calling us to learn more about how you can help.

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