Understanding Genetics

People with Parkinson's disease (PD) experience major differences in their symptoms, responses to medications and side effects of treatments. Understanding genetic differences across people with Parkinson's can help uncover important clues about how and why each person's experience with PD differs.

Genetics is the field of science that examines how traits are passed down, or inherited, from parents to children through genes. Genetics has transformed our knowledge of PD and paved the way for many innovations in treatment.

The study of genetics begins with our DNA. Think of our DNA as a cookbook that contains about 23,000 genes, or recipes, that make us who we are. A gene is like a recipe used to build a protein (that helps our bodies perform different jobs to function normally). Changes, known as mutations, in our genes can change the recipe — altering the shape and normal function of proteins in our body.

Changes in our genes are mostly harmless, but in some cases, they can affect our risk of getting a disease. Understanding these changes in genes is the basis for the Parkinson's Foundation PD GENEration: Mapping the Future of Parkinson's Disease study, which aims to determine the genetic makeup of 15,000 people with Parkinson's in the U.S.

In addition to genetics, environmental factors and lifestyle choices strongly determine if Parkinson's will develop. Understanding the role of genes and PD can help pave the way to understanding the biological causes of disease and developing novel therapies to treat Parkinson's.

Common Genetic Mutations

One major challenge in treating Parkinson's is that no one can predict how the disease will manifest in different people. No two people with Parkinson's seem to experience the exact same symptoms, age of onset, rate of progression and even treatment response. Genetics may help explain some of these differences.

Scientists have identified mutations (or changes) in several genes associated with Parkinson's. However, certain mutations seem to be more common than others.

These gene mutations change the role a protein plays and influences the risk for developing Parkinson's. Not all people with gene mutations develop Parkinson's and by understanding different inherited genetic backgrounds of people with Parkinson's, we can begin to understand what causes some people to develop certain symptoms while others do not.

Below are the most common mutations in genes that are associated with Parkinson's. Each mutation interrupts a protein from its normal workload, increasing the risk of developing Parkinson's:

• GBA: most common Parkinson’s-related gene, accounting for 5 to 10% of people with PD. Carriers may experience PD symptoms at an earlier age compared to people who don’t have a genetic form of PD. Learn more about GBA.
• LRRK2: plays a role in about 5% of those with a family history of Parkinson’s. Carriers have been reported to have milder symptoms of dementia and depression. Learn more about LRRK2.
• PRKN: the most common genetic mutation associated with young-onset Parkinson’s, which appears before age 50. Carriers may be more likely to experience early symptoms such as bradykinesia (slowness of movement) and rigidity. Learn more about PRKN.
• SNCA: first PD-related gene to be identified, commonly associated with young-onset Parkinson’s. Carriers usually have a parent with Parkinson’s. SNCA variants are a rare cause of Parkinson’s. Learn more about SNCA.
• PINK1: second most common gene associated with young-onset Parkinson’s. Carriers generally experience slow disease progression and respond well to the PD medication levodopa. Learn more about PINK1.
• PARK7: Variants in this gene are tied to young-onset Parkinson’s and lead to a decrease in a protein called DJ-1 that is essential for nerve cell health. Learn more about PARK7.
• VPS35: Only discovered in 2011, this is a rare genetic mutation recently tied to Parkinson’s. Learn more about VPS35.

Genetic Research

Genetic research has made great strides to help scientists better understand the biology of Parkinson's and guide the development of treatments for all people with PD. In the near future, knowing a person's genetic background may help predict the most effective treatments.

The Parkinson’s Foundation genetic study, PD GENEration, provides genetic testing and genetic counseling at no cost to people with Parkinson’s. The study’s comprehensive genetic test identifies variants in all of the above Parkinson’s-related genes.

Identifying whether you carry a genetic mutation can help you better manage your disease alongside your doctor and determine if you are eligible to enroll in more clinical trials. Enroll now in the PD GENEration study online.