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Q My two older brothers and older sister all have Parkinson's disease. My two younger brothers and I have shown no symptoms of the disease at this time. What are the odds that we three other siblings will develop PD?
DR. ZBIGNIEW K. WSZOLEK RESPONDS:
A The chance that you have the genetic form of Parkinson's disease is relatively high, but it's impossible to say how high without knowing more about your family history. For example, knowing if you have a parent or grandparent with Parkinson's can clarify whether your family carries one of five major genes thought to cause the disease.
The best advice I can give you would be to visit a genetic clinic—available at most major universities—where you can undergo a test to learn whether you are a genetic carrier or not. A genetic counselor can also explain to you the pros and cons of testing. It's important to realize that knowing you are a mutation carrier will not change anything, because we don't have a treatment available to halt progression of the disease. But some people are interested in genetic testing because they feel they can use the information to modify their lifestyle; some may choose not have children, for example, while others may decide to join clinical trials. Also, knowing whether or not you are a gene carrier may bring some piece of mind.