Spinal Muscular Atrophy (SMA) is a genetic disease that affects nerve cells called motor neurons, which control voluntary muscle movements. In this condition, muscles cannot respond properly to signals from nerve cells in the spinal cord. This leads to the progressive weakening, shrinking, and eventual loss of function (atrophy) of the muscles.

Consequently, patients lose control over their arm, leg, head, and neck muscles. Basic movements such as walking, crawling, head and neck control, swallowing, and breathing are also adversely affected. Although SMA causes severe muscle loss and weakness, senses such as sight, hearing, taste, smell, and touch, along with mental and emotional functions, remain entirely normal.