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Genetics and the Potential for Developing Parkinson’s

“Am I going to get Parkinson’s?”

That was one of the questions I asked my first neurologist in the initial year we worked together in a (failed) attempt to manage my intractable migraine. While I was only in my twenties at the time, and exhibited no warning signs of the disease, it still weighed heavily on my mind due to a strong family history.

“We don’t have any tests to check for it yet,” she replied, “and even if we did, would you really want to know?”

This was 2008, and I’m still not sure if I really want to know. However, genetic testing for certain genes is now available (specifically, PINK1, PARK7, SNCA, and LRRK2), though there is still some debate over how meaningful those results will be. The science on Parkinson’s has come a long way since 2008, however, and at least some of what I read calms my nerves.

The statistics

While there are approximately 60,000 new cases of Parkinson’s disease identified in the U.S. each year, and more than four million people live with the disorder worldwide, only about 15 percent of people with Parkinson’s have a family history of the disorder, according to the U.S. National Library of Medicine.

For that 15 percent, the genetic factors of the disorder are likely of interest. As of 2014, seven genes had been identified in the development of Parkinson’s disease: SNCA (PARK1), UCHL1 (PARK 5), LRRK2 (PARK8), (PARK3), PARK2 (PARK2), PARK7 (PARK7), and PINK1 (PARK6).

Understanding genetic inheritance

We each have two copies of every gene in our body, creating a pair. We inherit one copy of the gene from our mother and the other copy of the gene from our father. We then pass down to our offspring one of the two copies of each pair. Which copy that will be — the one we inherited from our mother or the one we inherited from our father — is random. Each copy in a pair has as much of a chance to be passed down as the other.

In most cases, these copies work as they should or they are paired in such a way that the copy of a working gene makes up for the copy of a non-working gene and the person is healthy. The problem arises when this is not the case. If, for example, a person receives two non-working copies of the same gene (one from each parent) or if the working copy of a gene cannot accommodate for the non-working copy.

What does it mean for Parkinson’s?

In general, it means there is safety in numbers. The National Human Genome Research Institute believes that inheriting a non-working copy of a single one of the seven identified genes associated with Parkinson’s will not cause the disorder. Instead, they say “other complicating factors such as additional genes and environmental factors determine who will get the condition, when they get it and how it affects them.”

Basically, it appears that inheriting multiple mutations of these genes or experiencing certain epigenetic or environmental factors in addition to inheriting non-working genes most likely contributes to developing the disorder. This makes me feel better personally, because it’s statistically less likely to inherit multiple non-working genes that affect the same thing. However, there is one caveat. When discussing what makes a genetic cause more likely, the National Human Genome Research Institute does say this:

“When three or more people are affected in a family, especially if they are diagnosed at an early age (under 50 years) we suspect that there may be a gene making this family more likely to develop the condition.”

As someone whose family history lies close to that scenario, I’m concerned. Especially given that I have chronic migraine with aura, and women with aura who experience migraine in middle age are more likely than others to have Parkinson’s disease and/or symptoms of Parkinson’s later in life. Will I rush out and get the available testing, though? Probably not. After all, 15 percent is still small. Most instances of Parkinson’s disease appear to be caused by something other than genetics. I’ll probably continue to take my chances with the unknown.

What about you? Have any of you had genetic testing for Parkinson’s? If so, are you glad you did?

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The ParkinsonsDisease.net team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

Comments

View Comments (2)
  • Gabro13
    9 months ago

    Interesting article. In answer to your question, no I have never had genetic testing even though my grandmother had PD and a cousin of mind from the same side of the family has it.

    One thing you mentioned is your doctor asked if you really want to know? For me my family doctor kept asking me for 3 years about the tremor in my left hand. I kept saying everything was fine until things got to a point where she said you are going to see a neurologist. The tremors became worse and I was dropping things in the same hand. I had other things going on that I always had an excuse for. I was 49 when diagnosed.

    People always ask why I wasn’t angry that my doctor didn’t do something about it sooner. I kept telling everyone that asked “look I got 3 more years without thinking or worrying about Parkinson’s disease. That was 4 years ago. Since then the meds have climbed to levels I never thought of. Slowness, tremors both hands, and feet, legs and a number of the non motor systems. I don’t see how it could have made a difference.

    It’s not like I was not an active person as I was regular running. Full marathons, half marathons. To me when it decides to come out from behind the shadows it comes weather you do all the right things to lead a healthy life or not.

  • KellyW moderator
    8 months ago

    Hi Gabro13! I was diagnosed 16 years ago at the age of 29. My dad was diagnosed about 4 years ago at the age of 74. We are fairly certain that my Grandmother had an undiagnosed case of Parkinsons. My Dad and I both did the genetic testing through 23andme.com and neither of us tested positive for Parkinson’s.
    I asked my MDS about additional genetic testing and he said it would not change the course of treatment. Maybe one day…. we can hope.
    I think you are right. When it decides to rear its ugly face, all we can do is do our best to fight back.
    Thanks for commenting! Regards, Kelly, ParkinsonsDisease.net Team Member

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