Genetic testing and Parkinson's
It is generally agreed that genetic as well as environmental factors lead to
the onset of Parkinson’s. Research is ongoing to determine the extent to which
both of these factors play. It is currently estimated that in approximately
five percent of cases of Parkinson’s there may be a genetic cause. This means that the remaining 95 percent have
an idiopathic form of the disease (the causes of their condition cannot be
confirmed).
Although there are a few families in which more than one person develops
Parkinson’s, it is rare for the condition to be passed down from one generation
to the next. Researchers largely agree
that the condition arises as a result of genetic susceptibility and an external trigger, such as
environmental chemicals for example, although these mechanisms are still not
fully understood by scientists.
At the time of writing (spring 2011) at least 13 genes have so far been
identified that seem to contribute to Parkinson’s. It is important to note,
however, that a mutation of one of these genes does not necessarily mean that
the condition will develop. Current genetic research tends to focus primarily
on the parkin, PINK1, PARK7, SNCA and LRRK2
genes. Mutations of these genes appear
to be part of the underlying causes of Parkinson’s, sometimes with multiple
mutations of a single gene, although the role they play and the mechanisms
involved are not yet clear.
Genetic testing for some Parkinson’s genes is now commercially available but
is primarily used for research purposes. As our understanding of genetic links
to Parkinson’s grows, scientists hope to develop reliable tests to identify who
is at risk. This should help with early
diagnosis, even before symptoms appear. As disease modifying and
neuroprotective treatments are developed together with new medications, it will
become increasingly important to assess genetic risk and to make a diagnosis as
early as possible so that treatment can begin promptly.
At present though, because our understanding of genetics and Parkinson’s is
limited, and because the incidence of genetically caused Parkinson’s is rare,
testing for the condition, which is expensive and time consuming, is not
routinely offered. If an individual is
tested though, and an increased risk is found, regular monitoring may be
arranged to detect early symptoms of the condition.
Who can help?
If you want to find out more about genetic testing your doctor should be
able to put you in contact with a specialised genetics health professional.
