spinal muscular atrophy

Spinal muscular atrophy (SMA) is an incurable autosomal recessive disease caused by a genetic defect in the SMN1 gene which codes SMN, a protein necessary for survival of motor neurons, and resulting in death of neuronal cells in the anterior horn of spinal cord and subsequent system-wide muscle wasting (atrophy).

Spinal muscular atrophy manifests in various degrees of severity which all have in common general muscle wasting and mobility impairment. Other body systems may be affected as well, particularly in early-onset forms. Spinal muscular atrophy is the most common genetic cause of infant death.

Sometimes, the term spinal muscular atrophy is used to encompass other hereditary disorders that involve death of motor neurons in the anterior horn of spinal cord - see spinal muscular atrophies.