Spinal muscularatrophy is a genetically determined group of neuromuscular diseases. It is characterised by loss of spinal cord neurons leading to progressive paresis and muscle atrophy. In the spinal cord of SA sufferers, there is a deficiency of the SN protein found in the motor neurons that innervate the muscles in healthy individuals. The disease has an incidence of 1 in 6 000 babies born and is the most common genetic cause of death in infants and young children.