Genetic Testing and You

From James Beck, Ph.D., Director of Research Programs

The genetic testing company 23andMe recently announced that it had reached its goal of enrolling 10,000 people with Parkinson’s into its genetic testing program. I personally think that is fabulous.

While genetic abnormalities that lead to Parkinson’s disease are rare, finding these cases has been a boon to understanding PD for all. From the location and then discovery of the first PD gene by PDF’s first supported fellow, Roger Duvoisin, M.D., and his colleagues in 1996 to the more recent genetic discoveries of today, PDF steadfastly supports research into understanding how genetics and PD interact.

As we move forward, genetic testing is becoming more sophisticated and cheaper too as the cost drops faster than comparable advances made in computing technology. This is akin to buying the original IBM PC desktop one day and then next year being able to bring home the latest iPad.

Low costs are making genetic testing more ubiquitous and that is causing some problems. For scientists, the problems are a bit academic—they are drowning in data. For the PD community, these problems hit closer to home. Genetics testing has the potential to bring forth knowledge that before was unknowable—the future. The question now is are we ready?

Deciding to voluntarily undergo genetic testing is a very personal decision; and, like many other endeavors, it is not always happy sailing. This is why, in response to the many questions and concerns PDF has received about genetic testing, PDF tasked our Medical Policy Committee to provide guidance for those interested in gene testing.

Why does this matter? Let me tell you the story I heard about a person with PD who decided to buy a gene test kit.  This person wanted to see if he had a genetic cause to his disease.  Not surprisingly, the answer was no; he did not have a mutation in the few PD genes that are examined on a consumer level. However, he got more than he bargained for and what he did find out was not good. In his DNA were two copies of the bad variant of the APOE gene. He now knew he was at a 10-fold increased risk of developing Alzheimer’s disease—information he did not want nor was he prepared to know.

Fortunately, most scientific studies involving gene testing do not reveal the results to those who participate. Providing a blood sample for PD research remains a very easy way for everyone to become participants in the research process, moving us all closer to finally tackling this disease.

As it stands today, nearly 90 percent of the people with PD do not have a clearly attributable genetic cause to their disease. Since consumer testing only looks at a handful of the known PD genes, the odds of using a consumer test to unveil a personal PD-genetic link are rare. And for those who do, that knowledge will not affect their current medical care. The bottom line with genetic testing is to look before leaping. Take the time to understand what you are buying and deciding what that knowledge is worth to you.

3 thoughts on “Genetic Testing and You

  1. Mariodacatsmom

    Since I’m a senior over 70 and both my husband and I have PD, I’d still like to be tested just to see where it came from. Might be valuable for our daughter. My mother also had Alzheimers and PD. Double Whammy! Thank you for your very informative articles – I always read them.

  2. Linda Morgan, Person with Parkinson's

    My understanding is that 23andme goes to particular ‘lengths’ to ‘lock’ specific results such as the PD gene results and Alzheimer’s. If the individual really did not want to know his APOE gene status until he was prepared he could have chosen not to ‘unlock’ the data. In other words it does not appear un-expectantly on the data page , for example. One has to read an explanation and then choose to know and unlock the information. That said, I agree we need to be prepared before we leap. Thank you, Dr. Beck!

  3. Dr. James Beck

    @Mariodacatsmom – You bring up an interesting issue that I hope you also consider…how knowledge of your own genes affects others. Some children want to know, others do not. Part of involving a genetic counselor is to help facilitate some of these important and frank conversations. Good luck on your decision.

    Linda Morgan – Yes, I too know that 23andMe does not allow one to easily happen upon what could be upsetting results. For those who carry a mutation in LRRK2 (one of the few genes tested), there is even a video featuring a brief discussion by Dr. William Langston. This company also now offers a discount for a telephone consultation with a genetic counselor, which is important.

    That said, I believe that people should be fully informed before being faced with the decision to read or not to read that section of their genetic testing report.

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