Dr. Liani Smit
Clinical Geneticist (PathCare)
Genetic testing for Motor Neuron Disease (MND) is complex and not yet widely accessible in South Africa. However, it can play an important role in empowering people living with MND and their families by helping them make informed care decisions and offering hope for more personalised treatment options in the future.
Understanding the Causes of MND
The cause of MND is still not fully understood for most people diagnosed with the condition. Generally, MND is divided into two types: sporadic and familial. Sporadic MND happens “out of the blue,” without any known family history, and makes up about 85-90% of cases. Familial MND, which is inherited, accounts for 10-15% of cases and is linked to specific genetic changes passed down through families.
One of the most common genetic causes of MND is a change called the C9orf72 gene repeat expansion. This cause is found in nearly 40% of familial MND cases and about 7% of sporadic cases. There are also other genetic variants that contribute to MND, but these are less common.
The Role of Genetic Testing in MND
MND is diagnosed mainly through clinical examination, where neurologists rule out other conditions that might look similar. Genetic testing can confirm a genetic cause, but a negative test does not rule out MND. As research advances and new targeted treatments become available, genetic testing is becoming a more important part of managing MND, even for those without a family history. It also helps families understand the chances of MND occurring in future generations and it can therefore help guide their lifestyle choices and family planning.
Availability and Approach to Genetic Testing in South Africa
International guidelines from 2023 now recommend that genetic testing can be offered to all people diagnosed with MND. Priority is given to those with a family history of MND or frontotemporal dementia (FTD), or those diagnosed before age 50, as they are more likely to have a genetic cause.
In South Africa, access to genetic testing is still limited, especially in the public healthcare sector. In private healthcare, testing is frequently outsourced to international laboratories. A comprehensive MND multi-gene panel, which includes the C9orf72 test, costs around R8500. These tests are generally not covered by medical aids and must be self-funded.
The preferred approach is to test an affected family member first, if possible. If a genetic cause is found, other family members may consider testing for the familial cause, after comprehensive genetic counselling.
Testing Asymptomatic Family Members
Family members who do not have symptoms but want to know their risk of developing MND may consider predictive genetic testing. This is a big decision and involves careful consideration of the emotional and psychological impact of the results on them and their family members. Predictive genetic testing is therefore only offered after consultation with a genetic counsellor, and sometimes a psychologist and neurologist, to ensure that the person is emotionally ready and has adequate support.
Genetic Counselling
Genetic counsellors are trained genetic healthcare professionals registered with the Health Professions Council of South Africa (HPCSA). They help individuals and families understand genetic test results, provide emotional support, and assist with difficult decisions. Ideally, genetic counselling should happen both before and after testing to ensure everyone fully understands what the results might mean for them and their family.
If you are interested in genetic testing or genetic counselling for MND, you can find a list of genetic professionals in the private and public sectors at, SASHG Genetic Services or you may reach out to the genetics team at PathCare for a list of genetic counsellors in private practice: geneticconsult@pathcare.net.