What Is SMA

In the spine, there is a particular gene (SMN1) that produces a particular type of protein. That protein is essential to the healthy development of motor neurons, which people need in order to do many things: breathe, swallow, walk, run.

In SMA patients, the SMN1 gene is defunct and either doesn’t produce the necessary proteins at all or doesn’t produce enough of them. So the motor neurons are weak or die off, leaving the body’s muscles to atrophy without use.

Learn about 25 years of FightSMA-funded research

Click here to see list of FightSMA-funded institutions

Watch video of researchers explaining SMA and how FightSMA is working toward a cure.

Click here to read information about SMA from the National Institute of Neurological Disorders and Stroke (NINDS).

Click here to research SMA clinical trials.

FightSMA // What is SMA Infographic

SMA is generally classified into four Types, based on a clinical identification of distinguishing physical milestones.

It is important to note that identifiable symptoms of SMA fall along a spectrum, and there can be overlap between the classification of Types. As a genetic disease, SMA presents a wide variability of progression and onset, and each patient will be unique.


Symptoms present by 6 months

The most severe form of the disease, Type 1 SMA symptoms are present during infancy. Affected children will not acquire the power, the strength, and the endurance to sit up independently, to crawl, or to walk. The challenge of basic respiration often poses the most critical risks to the health of an SMA 1 patient. It takes a team, usually captained by the family, and implemented in a neuromuscular center to meet the needs to provide for the ultimate healthcare support for a Type 1 infant.


Symptoms present by 18 months

Type 2 SMA usually comes to medical attention before the age of 18 months because of respiratory insufficiencies experienced by the child. Early motor milestones, such as achieving head control, turning and rolling in the crib, are frequently passed on time. SMA 2 presents a significant list of medical challenges, and the potential for surgical interventions may be more frequent; a child affected by Type 2 is unlikely to walk unassisted.


Onset in childhood

Children may be diagnosed with Type 3 SMA as early as 18 months of age or as late as adolescence; many are diagnosed before the age of three. Children with SMA 3 be ambulatory with at least some to full walking, but may lose this ability later in life.


Onset in adulthood

Diagnosed after the age of 18 and by the age of 50, the symptoms of Type 4 SMA can otherwise be similar to that seen in Type 3, including muscle wasting, weakness, and tremors. The muscles used for swallowing and breathing are less likely to be affected in adult onset SMA.