Is Parkinson's Disease Hereditary? Here's Why You Shouldn't Panic About Your Genetic Risk

Genetic markers for Parkinson’s disease can run in families, but it’s rare to inherit it. Here’s what to consider if a relative has Parkinson’s.

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Getty Images / AdobeStock / Jo Imperio

When people are diagnosed with Parkinson's disease, they often want to know if it's hereditary. Can their kids get it? Are their grandchildren at risk? Well, the answer is complicated. "Most of the time we don't know what is really causing the disease in people," Irene Litvan, MD, director of the Movement Disorders Center at the University of California, San Diego, told Health.

What Is Parkinson's Disease?

Parkinson's disease is a disorder of the brain that causes nerve cells to die. This disease progressively worsens over time and the cause is unknown, according to the National Institute on Aging. People with Parkinson's disease may experience any of these symptoms:

  • Shaking
  • Difficulty balancing
  • Muscle stiffness
  • Depression
  • Difficulty talking and eating
  • Changes in behavior
  • Constipation
  • Urinary problems
  • Slow movements

Just because you have a mutation on a certain gene or a relative with Parkinson's doesn't mean you're definitely going to get the disease. According to the National Institute on Aging, a combination of factors (age, environment, and yes, genetics) contribute to the disease, but the extent to which each factor impacts a person varies from case to case.

Parkinson's isn't considered a hereditary disease in most people. According to the Parkinson's Foundation, genetics is the cause in 10% to 15% of patients with Parkinson's.

Let's take a closer look at the genetic factors associated with Parkinson's disease and just how hereditary the disease really is.

What Genetic Factors Play a Role?

While there are some genetic markers for Parkinson's, they don't guarantee that a person will get the disease, according to the Parkinson's Foundation. A genetic mutation is just one of several risk factors for Parkinson's disease. According to the National Institute on Aging, there may also be lifestyle choices and environmental factors involved in the development of the disease. In fact, most people with Parkinson's disease aren't aware of any other family member with the condition, according to the National Human Genome Research Institue (NHGRI).

Causal Genetic Factors

One of the genetic factors in play is called "causal," meaning the gene itself is capable of bringing on the disease, according to this review from 2020 in npj Parkinon's Disease. This kind of genetic predisposition to Parkinson's is super rare, accounting for less than 2% of Parkinson's disease cases.

One example of a causal link to Parkinson's disease can be found in the SNCA gene. Researchers know of at least 30 mutations on this particular gene that can cause Parkinson's disease, especially in people younger than 50 years old, according to MedlinePlus.

The SNCA gene tells the body how to make a protein called alpha-synuclein. When the SNCA gene has a mutation, the body may produce too much of this protein or with an incorrect shape, according to MedlinePlus. Either of these problems can lead to a cluster of proteins, which is called Lewy bodies. Lewy bodies disrupt normal brain functioning and are associated with Parkinson's, along with a range of other diseases.

Associated Genetic Factors

Not all genetic mutations cause Parkinson's disease, though. "Associated" genetic factors for Parkinson's increase a person's odds of developing the disease, but aren't directly responsible for it. "You're susceptible, but you need something else present as well [to actually get the disease]," Dr. Litvan said. "That could be other genes or it could be an environmental factor."

An example of an associated Parkinson's gene is LRRK2. Mutations on this gene can lead to the loss of neurons (which play a role in helping the brain store memories), according to this article from 2018 in Current Neuropharmacology.

There are also mutations on the GBA1 gene, which is the most common genetic abnormality linked to Parkinson's disease. According to an article from 2018 in Parkinson's Disease: Pathogensis and Clinical Aspects, about 5% of patients with Parkinson's disease have a mutation on the GBA1 gene. If you have this genetic mutation, your risk for developing Parkinsons' disease is increased.

There are many other genetic mutations that have been linked to Parkinson's, and ongoing research will continue to uncover other markers for the disease.

Should I Get Tested for Genetic Markers for Parkinson's?

You can find out if you have certain genetic markers for Parkinson's disease with at-home genetic tests. However, Dr. Litvan is cautious about recommending genetic testing for everyone. Remember: Most people with the mutations linked to Parkinson's never get the disease, so you may end up with a ton of unnecessary stress and worry if your results reveal one of these genetic factors.

Generally speaking, you should consider testing for genetic markers for Parkinson's if you have a family history of the disease, said Lynda Nwabuobi, MD, a neurologist at New York-Presbyterian Hospital-Columbia and Cornell.

"If I see a patient who comes in and they have Parkinson's, their mother had Parkinson's, their maternal grandparents had Parkinson's, or they also have another sibling who has Parkinson's, there's clearly some family history," Dr. Nwabuobi told Health. "And to those individuals, I'll say, 'Let's get you genetic testing.'"

By getting tested, people with Parkinson's (or with a family history of it) can give scientists more information to work with in the grand scheme of medical research—and potentially tee themselves up for access to groundbreaking medicine.

"If you're someone who has, let's say, the GBA gene, and in five years [a treatment] comes out that's specific for patients with that gene, you would want to know, right?" Dr. Nwabuobi said. "So that's a good reason to get tested."

Summary

With all that said, a variety of factors, including genetics and your environment, contribute to Parkinson's disease. Most people that have genetic mutations associated with Parkinson's never actually get the disease. So while it can be helpful to be aware of Parkinson's genetic factors in some situations, you don't need to panic if you have one of these genetic mutations.

Keep in mind, researchers are still learning; they still don't know the exact cause for Parkinson's disease. Even with all of the information that has been discovered, there is still much more to learn.

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