What is Spinal Muscular Atrophy?

Spinal Muscular Atrophy (SMA) is a type of motor neuron disease caused by a missing or mutated gene on chromosome 5 called SMN1. This gene is essential for the health of motor neurons—nerve cells found in the spinal cord that are responsible for voluntary muscle activities such as crawling, walking, head and neck control, and swallowing. With a missing or mutated SMN1 gene, nerve cells decay, shrink, and eventually die, resulting in muscle weakness.

Spinal muscles can be affected by SMA. When spinal muscles weaken, they are no longer able to hold the spine straight. One of the most common spinal conditions for people with SMA is scoliosis. In scoliosis, the spine curves, resembling an S or a C. Scoliosis is a "three-dimensional" curve, meaning that the spine can twist in addition to curving side-to-side. As the vertebrae (the bones that make up the spine) rotate, they may cause lung problems and/or progressive deformity.

For wheelchair-bound patients with SMA, scoliosis can also cause considerable pain as the abnormal curves make sitting very uncomfortable.