Genetics

Two decades ago, researchers established that Parkinson’s has a genetic connection. Since then, genetic research has opened up a whole new world of possibilities for understanding, diagnosing and treating Parkinson’s disease (PD). It’s uncovering Parkinson’s pathways and guiding development of therapies that could potentially slow or stop PD. Today, genetic research is one of our best routes to overcoming knowledge and treatment gaps in Parkinson’s.

While many Parkinson’s patients report one or more family members with the disease, it is not always clear that one or several genes are the cause. Scientists currently believe that in the majority of cases, genetic and environmental factors interact to cause Parkinson’s disease. Research into this subject continues aggressively every day.

It’s important to note that if you do have a genetic mutation associated with Parkinson’s you do not have a 100% chance of developing the disease. In fact here are many Parkinson’s risk genes where a mutation means a very small increased likelihood of Parkinson’s.

Questions

If I have a Parkinson’s Mutation, will I get the disease?

In short: not necessarily. We know that some people have mutations in the SNCA or the LRRK2 gene and never develop Parkinson’s symptoms.

In addition, there are Parkinson’s risk genes where a mutation means an increased likelihood of Parkinson’s (not a direct causal link). Researchers are looking for other factors (environmental factors or other genetic mutations, for example) that either push or protect someone with a gene mutation to/from having Parkinson’s.

Should I get Genetically tested

There is a critical role for Parkinson’s patients and their loved ones to play in the pursuit of a cure by being genetically tested and participating in clinical research.

That said, the decision to find out one’s genetic makeup and disease risk is a personal one, and it is important to discuss with your family and health care provider. Also consult with a qualified genetic counselor both before and after receiving your results to understand all of the issues involved.

For now, learning your Parkinson’s genetic status does not change your personal prevention or treatment regimen. But by coming together, people with certain mutations can help speed discovery and make a significant contribution to Parkinson’s drug development.

Finally, remember that having a genetic mutation associated with Parkinson’s does not mean you will get the disease.

Risk Factors

Because the causes of Parkinson’s disease are unknown, there is no scientifically validated preventive course to reduce the risk of its onset. The single biggest risk factor for Parkinson’s disease is advancing age. Men have a somewhat higher risk than women.

That being said, a number of studies have highlighted factors that are associated with either greater or lesser risk of Parkinson’s disease. For example, smoking and caffeine consumption have been associated with lower rates of Parkinson’s disease, while head injury and pesticide exposure have been associated with higher risk. While such studies do not definitively link these factors with Parkinson’s disease one way or another, they highlight areas where further research may guide us to risk-prevention or treatment strategies.

Genetics and Parkinson’s is a complicated topic, and it can raise many questions. For more information on participating in genetic research or genetic testing, check out our Trial Participant Pack, which includes a book (Chapter 3 covers genetics), videos and other resources.

Genes Connected to Parkinson's

SNCA (Alpha-synuclein)

In 1997, researchers at the National Institutes of Health made the first Parkinson’s genetic connection, discovering that mutations in the SNCA gene were common in several families who had many members with Parkinson’s. While mutations in this gene are rare, they have taught us invaluable information about PD.

The SNCA gene instructs the body to make the protein alpha-synuclein, which for reasons that are not yet known, clumps in the brain cells of people with PD. Study of the SNCA gene led to this understanding that applies to nearly all people with the disease. Since then, alpha-synuclein has been a major target of new drugs for Parkinson’s.


LRRK2 (LRRK2 protein)

Another gene that plays a role in Parkinson’s is LRRK2, which accounts for one to two percent of all cases. For people of particular ethnic backgrounds — Ashkenazi (Eastern European) Jewish and North African Berber descent — mutations in the LRRK2 gene account for a much greater number of cases than in the general PD population. Mutations in LRRK2 lead to too much activity of the LRRK2 protein, though recent research indicates people without a mutation can also have overactivity of LRRK2.

Shake It Up are funding several studies into LRRK2 and you can learn more about these here.

GBA (GCase)

Mutations in the glucocerebrosidase beta (GBA) gene are the most common of the currently known PD genetic mutations and also more common in people of Ashkenazi Jewish descent. GBA mutations increase a person’s risk of Parkinson’s, but less so than mutations in SNCA or LRRK2. The GBA gene instructs production of the glucocerebrosidase (GCase) protein, and mutations are associated with not enough GCase activity.

PRKN (Parkin)

A common genetic contributor to young-onset Parkinson’s (diagnosed before age 50) is a mutation in the PRKN gene, which manufactures the parkin protein. Scientists believe the parkin protein plays a role in recycling mitochondria, or the “power plants” of cells. In the same pathway with parkin lies PINK1 — another target where researchers may be able to intervene to boost parkin activity.

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