Understanding Genetic Conditions: Spinal muscular atrophy (SMA)

Genetic conditions are individually rare but when combined are likely to affect 1-2% of babies born every year and while genetic conditions are hugely variable in the way they impact health growth and development, they are rarely curable. 

Spinal muscular atrophy (SMA) is a devastating genetic disorder that affects the nerve cells in the spinal cord, leading to muscle weakness and atrophy. This condition can range from mild to severe, with the most severe form, known as SMA type 1, appearing in infants before the age of six months. These infants may have difficulty with movements such as sucking and swallowing, and may eventually lose the ability to move or breathe on their own.

SMA is inherited in an autosomal recessive manner, meaning that for an individual to be affected they need to inherit two copies of the SMN1 (Survival Motor Neuron) gene with a deleterious variation, one from each parent. Approximately 1 in 40 people are carriers of SMA. Carriers are healthy and have no way of knowing this unless reproductive carrier screening is performed as part of pre pregnancy planning of early pregnancy care. When a couple are both found to be carriers of SMA, there is a 25% (1 in 4) chance with each pregnancy of having a child with SMA.

Carrier screening is recommended by RANZCOG and RACGP (the governing bodies for Obstetricians and GPs in Australia and New Zealand). For couples who find out that they have a high chance of having a child with SMA there are many options they can consider to reduce the chances of having an affected child. These can include, but are not limited to prenatal diagnosis of a naturally conceived pregnancy or IVF with Preimplantation Genetic Testing (PGT). For couples who know of their risk in advance, medicare support is available for both prenatal diagnosis and IVF. Your doctor is likely to recommend speaking to a genetic counsellor about your options.

Overall, SMA is a serious genetic disorder that can have a significant impact on individuals and their families. While the management and treatment for SMA has come a long way, it is still considered to be a life limiting condition Even though there is no cure, there are treatment options available to help manage the symptoms of the condition and improve the quality of life for those living with SMA.

One of these options is drug treatment called Nusinersen (marketed as Spinraza). This drug works by increasing the amount of the SMN protein, which is essential for the survival of motor neurons. It has been shown to improve muscle function and mobility in individuals with SMA. Another potential treatment option for SMA is gene therapy. In recent clinical trials, gene therapy has shown promise in improving muscle function and supporting life in individuals with SMA. However, more research is needed to fully understand the effectiveness and safety of this approach.

Carrier screening is an essential option for those who want to understand the chance of having a child with SMA. Eugene’s reproductive carrier screening test is designed to let couples and individuals know if they are carriers of SMA, as well as more than 560 other genetic conditions. This information supports people to make informed decisions about their family planning and pregnancy care options.Eugene’s genetic counsellors support you before, during and after results, and can help you make the best decision based on your values and needs.

Explore the latest reproductive carrier screening options fully supported by our genetic counsellors.