Parkinson's Disease Blog

Does Parkinson’s have a genetic component even though it is not hereditary?

Another way of putting this question might be: ‘Does Parkinson’s have something to do with a person’s genes (the building blocks controlling the amount and type of proteins produced), which then affects various interactions with each other and environmental factors, even though it is not handed down directly from parent to child?’ This is an important question, but it is impossible to give a simple answer.

Researchers went through a stage of thinking that the genetic component in Parkinson’s was very small because it was very rare for both members of a set of twins to get the illness. However, this was true both of identical and non-identical twins. To really test whether or not there is a genetic component, oneneeds to see a difference between the two types of twins. As an example, if there was a strong genetic component, both members of sets of identical twins would get the illness much more frequently than non-identical twins. The numbers of twins found and tested was initially insufficient to come to a definite conclusion, but recent work suggests a considerable genetic component in people who develop Parkinson’s under the age of 50, and little or no genetic influence in those who develop it later.

Most people now believe that, as with many other common conditions, Parkinson’s is likely to have a genetic component which makes some individuals susceptible to something in the environment, perhaps a chemical or a virus. Intriguing though this is, it does not alter the fact that the risk of the children of people with Parkinson’s also developing the condition is negligible.