Spinal Muscular Atrophy (SMA) Support Group

The most common form of SMA is caused by mutation of the SMN gene, and manifests over a wide range of severity affecting infants through adults. This spectrum has been divided arbitrarily into three groups by the level of weakness: Infantile SMA, Intermediate SMA, and Juvenile SMA.

The course of SMA is directly related to the severity of weakness. Infants with the severe form of SMA frequently succumb to respiratory disease due to weakness of the muscles that support breathing. Children with milder forms of SMA naturally live much longer although they may need extensive medical support, especially those at the more severe end of the spectrum.

Although gene replacement strategies are being tested in animals, current treatment for SMA consists of prevention and management of the secondary effect of chronic motor unit loss. It is likely that gene replacement for SMA will require many more years of investigation before it can be applied to humans. Due to molecular biology, there is a better understanding of SMA. The disease is caused by deficiency of SMN (survival motor neuron) protein, and therefore approaches to developing treatment include searching for drugs that increase SMN levels, enhance residual SMN function, or compensate for its loss.

Much can be done for SMA patients in terms of medical and in particular respiratory, nutritional and rehabilitation care. However, there is currently no drug known to alter the course of SMA. Significant progress has been made in preclincial research towards an effective treatment. Several drugs have been identified in laboratory experiments that hold promise for patients. To evaluate if these drugs benefit SMA patients, clinical trials are needed. In a clinical trial a new medication is tested while the patients are carefully monitored for their safety and for any possible drug effects, positive or negative.