Myth busting: Parkinson’s is a genetic condition

Is Parkinson’s genetic?

Only 10-15% of Parkinson’s cases are thought to be genetic. Most cases are actually caused by a mixture of genetics, environmental and lifestyle factors.

The interaction between genetics and environmental factors is not yet fully understood. But we do know that certain genetic mutations can increase your risk of developing Parkinson’s.

Genetics

Scientists have been studying the genetics behind Parkinson’s for decades. Comparing the genetics of people living with Parkinson’s has helped to discover dozens of gene mutations that can contribute to its development.

By comparing genetics, symptoms and the personal circumstances of people living with Parkinson’s, scientists have identified gene mutations that increase the risk of Parkinson’s:

• GBA – The most common genetic mutation, it accounts for 5-10% of all people with Parkinson’s. GBA is linked to an earlier onset of symptoms when compared to people with an idiopathic form of Parkinson’s.
• LRRK2 – Present in about 5% of people with a family history of Parkinson’s. It’s associated with milder symptoms of depression and dementia.
• PRKN – Most common with people who have young onset Parkinson’s. Carriers of this gene are more likely to experience slowness of movement (bradykinesia) and rigidity.
• SNCA – SNCA is associated with young onset Parkinson’s. This variant of Parkinson’s is rare, and carriers often have a parent with Parkinson’s.
• PINK1 – The second most common gene found in people with young onset Parkinson’s. PINK1 carriers typically experience a slow progression of symptoms.
• PARK7 – Mutations in this gene are related to young onset Parkinson’s. It causes a decrease in DJ-1 proteins, which are important for nerve cell health.
• VPS35 – VPS35 was only linked to Parkinson’s recently, and relatively little is known about what Parkinson’s looks like for carriers.

Carrying one of these gene mutations does not guarantee you will develop Parkinson’s. Similarly, it’s possible to develop the condition even if you don’t carry any of the known genetic mutations.

Environmental factors

Researchers have identified dozens of environmental factors that may contribute to developing Parkinson’s. Like with genetics, there’s no consensus, and the current research often shows conflicting results.

Below are some environmental factors that are thought to contribute to Parkinson’s:

• • Age – Age is the greatest risk factor associated with Parkinson’s. Most people begin to experience the onset of symptoms at age 60. Parkinson’s occurs in people aged 20 to 50 in about 20% of cases. This is referred to as young onset, or early onset, Parkinson’s.

• Gender – Parkinson’s occurs slightly more frequently in men than women.

• Head trauma – Traumatic brain injury is a risk factor for Parkinson’s. However, not everyone who experiences head injury will develop Parkinson’s.
• Farming chemicals – Research has shown a strong link between Parkinson’s and exposure to pesticides and herbicides. These chemicals build up in our soil and waterways, so you can be at risk even if you don’t have direct contact with these types of chemicals.
• Exposure to metals – Long-term exposure to heavy metals (like iron, mercury, manganese, copper and lead) are linked to cases of Parkinson’s.
• Trichloroethylene (TCE) – Solvents and cleaning chemicals that are classed as TCEs have been linked to Parkinson’s. These chemicals are a common environmental contaminant, so you can be at risk of exposure, even if you don’t work with these chemicals directly.

Lifestyle factors

Lifestyle factors like nutrition and exercise are also thought to play a role in Parkinson’s. Research suggests that regular exercise and higher levels of vitamin D can reduce the likelihood of Parkinson’s. Taking vitamin supplements can have adverse effects on your health – consult your doctor before taking any supplements.

Like with environmental factors, it’s challenging to pinpoint the effect that lifestyle has on Parkinson’s. More research is needed, but we generally recommend staying active and maintaining a balanced diet if you want to manage your risk.

What if I carry the gene for Parkinson’s?

Carrying a gene mutation that’s related to Parkinson’s does not guarantee you will develop the condition. Some people never develop Parkinson’s, despite carrying mutations in the associated genes (e.g. LRRK2 and GBA).

If you are genetically predisposed to Parkinson’s, you may be at greater risk from environmental or lifestyle factors. The complexity of the condition and environmental factors makes it difficult to determine your personal risk of developing Parkinson’s.

If I have Parkinson’s, will my children get it too? Will I inherit Parkinson’s from my parents?

Most people with a genetic link to Parkinson’s will never develop the condition.

Parkinson’s is inherited in just 10% of cases. This suggests that your children are unlikely to develop Parkinson’s, and that it’s unlikely you’ve inherited it from your parents.

How can I find out if I have the gene for Parkinson’s?

In Australia, genetic testing is usually only available if you are diagnosed with Parkinson’s and there is a suspected genetic cause. You can also participate in the Australian Parkinson’s Genetics Study (AGPS), regardless of whether you have Parkinson’s.

Contact us for more information on your Parkinson’s journey

Parkinson’s is not solely a genetic condition. It’s caused by complex interactions between genetic mutations, lifestyle and environmental factors. While the condition isn’t fully understood, researchers are working hard to develop treatments that improve care and wellbeing.

You can contact Parkinson’s Australia for more information. We’re a national advocacy body that works on behalf of Australians living with Parkinson’s.