ICD-11 definition : Spinal muscular atrophy (SMA) is a progressive disorder with loss of anterior horn
cells leading to muscle weakness and wasting. The weakness is typically symmetrical.
Typically, upper motor neuron signs are absent and there is no sensory deficit. Feeding
and swallowing can be affected, and involvement of respiratory muscles may occur.
SMA is an autosomal recessive disorder linked to chromosome 5q13 and the disorder
is caused by deletion or mutation of SMN 1 (spinal motor neuron 1) gene. The four
types of SMA I, II, III and IV are categorised based on the age of onset of the disease
and the ability to achieve motor milestones.;
Spinal muscular atrophy (SMA) is a progressive disorder with loss of anterior horn
cells leading to muscle weakness and wasting. The weakness is typically symmetrical.
Typically, upper motor neuron signs are absent and there is no sensory deficit. Feeding
and swallowing can be affected, and involvement of respiratory muscles may occur.
SMA is an autosomal recessive disorder linked to chromosome 5q13 and the disorder
is caused by deletion or mutation of SMN 1 (spinal motor neuron 1) gene. The four
types of SMA I, II, III and IV are categorised based on the age of onset of the disease
and the ability to achieve motor milestones.