Spinal muscular atrophy (SMA) is a rare inherited neuromuscular condition which affects the motor nerve cells in the spinal cord. It causes progressive muscle weakness and loss of movement due to muscle wasting (atrophy). It is the number one genetic cause of death of infants.
There are different forms of SMA and a wide spectrum of how severely children and adults are affected. This section gives an overview of the most common form – 5q SMA – which includes SMA Types 1, 2, 3 and 4.