DRPLA is diagnosed with a genetic test that checks whether a person has the specific change in their DNA that causes the condition. In DRPLA, this test looks for a section of the ATN1 gene that repeats the letters CAG many times. If someone has 48 or more CAG repeats, it confirms that they have DRPLA.
DRPLA is autosomal dominant, meaning that an affected person has a 50% chance of passing the expanded repeat to each child. Because of anticipation, children may inherit a larger repeat expansion than their parent, leading to earlier or more severe symptoms. This information is especially important for family planning and for relatives considering predictive testing.
Genetic testing can be used in two contexts:
- Diagnostic testing for individuals already experiencing symptoms suggestive of DRPLA.
- Predictive (presymptomatic) testing may be available to adults with a family history of DRPLA. Predictive testing is not recommended for individuals under 18 unless there is a clear medical benefit.
Undergoing genetic testing is a personal choice and should be discussed with your doctor on an individual basis. As part of the process, you will usually speak with a genetic counsellor. They can help you understand what the test involves and support you in deciding whether it might be right for you.
Eligibility, costs, and availability vary significantly by country and healthcare system. Some regions offer testing through national health services or research programs, while others require specialist referral or insurance approval. We recommend starting with your local healthcare provider or genetics clinic to understand your options. You can also reach out to us, and we may be able to direct you to resources tailored to your needs and local regulations.
To read more about how ataxia is diagnosed, refer to this page.
If you are based in the United States and would like more information, visit this page about genetic counseling and testing by CDC.
If you are based in the United Kingdom and would like more information, visit this page about genetic services and testing by Genetic Alliance UK.