Does Parkinson's run in families?

If you have Parkinson’s, it’s likely you have idiopathic Parkinson’s. This means the exact cause of the condition isn’t known.

A combination of your genes, lifestyle and exposure to things in the environment can mean that some people are more at risk of developing Parkinson's than others. 

How do genes increase the risk of Parkinson’s?

A gene is a section of DNA. It contains the instructions needed to make proteins, which play an important role in how your body works.

Everyone has differences in their genes that make them unique as a person. Small differences in genes can increase or decrease the risk of someone developing Parkinson's.

Families share differences in their genes. They are also often exposed to the same risk factors in the environment, such as diet or pollution. 

This means some families have a higher chance of getting Parkinson's, just like some families are more likely to have heart disease or diabetes because of their genes. However, in these situations, there's no clear pattern showing if or how Parkinson's is passed down.

The GBA1 gene

The most common gene differences that increase the risk of Parkinson’s are in the GBA1 gene.

• Differences in this gene are common. They’re found in up to 10% of people with Parkinson's.
• Not everyone with a difference in the GBA1 gene will get Parkinson's, but it increases their risk. Up to 13% of people with this gene difference develop Parkinson's by the age of 80.
• The way this is passed on is not yet clear. It doesn't seem to have a big effect on the family's overall risk of developing Parkinson's.
• People with differences in this gene may have worse movement and thinking and memory symptoms.

Will I pass Parkinson’s on to my children?

Rare differences in a single gene causes Parkinson's in about 4% of people.

These genes can be passed on between parents and children.

But carrying the gene difference doesn't guarantee your children will get Parkinson's - it often also depends on your partner's genes.

The LRRK2 gene

This is the most common gene to have differences known to cause Parkinson’s.

• Around 1% of people with Parkinson’s in the UK have a difference in the LRRK2 gene, which explains the cause of their condition. Differences in this gene are more common in certain populations, including people of North African and certain Jewish (Ashkenazi) heritage.
• Up to 40% of people who have the most common difference in this gene develop Parkinson's by the age of 80. It’s unclear why some people don’t go on to develop Parkinson’s.
• Someone with this gene difference has a 1 in 2 (50%) chance of passing it to their children.
• Your Parkinson’s symptoms may start later in life and be more mild if you have a difference in this gene.  

What if I'm a younger person with Parkinson’s?

Younger people with Parkinson's are more likely to have a rare gene difference that has caused their Parkinson’s. But this doesn’t mean they will definitely pass Parkinson’s to their children. 

This is a list of some of the genes linked to people developing Parkinson’s younger:

The PRKN gene

• Differences in this gene are more common for people diagnosed with Parkinson’s at a younger age (before 50).
• Between 2 and 15% of people diagnosed at a younger age may have a difference in the PRKN gene.
• If your Parkinson's is caused by differences in the PRKN gene, your children are unlikely to develop the condition. That's because both parents usually need this rare gene difference to pass it on. However, your children could still carry the differences in the gene.

The PINK1 gene

• Between 1 and 9% of people who have developed Parkinson’s at a younger age have a difference in the PINK1 gene.
• If your Parkinson's is caused by differences in the PINK1 gene, your children are unlikely to develop Parkinson’s. That's because both parents usually need this rare gene difference to pass it on. However, your children could still carry the differences in the gene.

The PARK7 (DJ-1) gene

• 1-2% of people who have developed Parkinson’s at a younger age have a difference in the PARK7 gene.
• If your Parkinson's is caused by differences in the PARK7 gene, your children are unlikely to develop Parkinson’s. That's because both parents usually need this rare gene difference to pass it on. However, your children could still carry the differences in the gene.

The SNCA gene

• Differences in this gene are very rare. They’re found in fewer than 0.1% (1 in 1,000) of people with Parkinson’s.
• Someone with this gene difference has a 1 in 2 (50%)  chance of passing Parkinson’s to their children.

Genetic testing for Parkinson's

Genetic testing checks your DNA to find differences in your genes that could affect your health or be passed to your children.

If you're thinking about getting a genetic test, there are a few important things to consider first.

Who can get a genetic test for Parkinson’s?

The NHS offers genetic testing for Parkinson’s, but it's usually only for people:

• diagnosed before age 50
• with a close family member who is directly related, and who was diagnosed with Parkinson’s at a younger age.

Even then, it might depend on your specific symptoms and family history.

Talk to your GP, Parkinson's nurse or specialist about whether there is a genetic testing service available in your area.

What can the test tell me?

• Getting a positive test means you have a difference in a gene associated with Parkinson’s.
• If you already have Parkinson’s, getting a positive test doesn't change your current treatment. However, it gives doctors more information about why you developed Parkinson's, options to join specific clinical trials and potential risks to your family.
• If you haven’t been diagnosed with Parkinson’s, getting a positive test doesn't always mean you'll definitely develop Parkinson's. This will depend on the specific gene difference found.
• A positive test may allow you to join drug trials for new treatments focused on people with a specific genetic link.
• A negative test means you don’t have a difference in a gene associated with Parkinson’s. This doesn't completely rule out a genetic link, as researchers haven't discovered all the possible gene differences yet.

Can I get tested through a research study?

More people are getting genetic tests through research. This is because researchers are keen to understand more about the genetics of Parkinson’s and if certain treatments work better for people with specific genetic differences.

It is vital that these studies are representative of everyone living with Parkinson’s to ensure future treatments are relevant for everyone.

Current research studies that involve genetic testing:

• PD Frontline
  Identifying people with GBA1 and LRRK2 differences (open to all people with Parkinson’s to take part).
• Parkinson’s families project 
  Open to people with a family history or early onset Parkinson’s or a Parkinson’s related condition to take part.
• The Parkinson’s progression markers initiative 
  Open to people with and without Parkinson’s.

Learn more

• Watch Genna, who has young-onset Parkinson's, and neurologist Professor Miratul Muqit discuss genetic Parkinson's (4 minute video)
• "Genetic testing has given me a lot of answers" - Debbie's story