Spinal muscular atrophy (SMA) is caused by a mutation in the survival motor neuron gene 1 (SMN1). In a healthy person, this gene produces a protein that is critical to the function of the nerves that control our muscles. Individuals with SMA don’t produce survival motor neuron (SMN) protein at high enough levels. Without this protein, those nerve cells cannot properly function and eventually die, leading to debilitating and sometimes fatal muscle weakness.
SMA affects approximately 1 in 11,000 births in the U.S., and about 1 in every 50 Americans is a genetic carrier. SMA can affect any race or gender.
There are four primary types of SMA—1, 2, 3, and 4—based on the age that symptoms begin and highest physical milestone achieved.
Individuals with SMA have difficulty performing the basic functions of life, like breathing and swallowing. However, SMA does not affect a person’s ability to think, learn, and build relationships with others.