Spinal muscular atrophy

Spinal muscular atrophy (SMA) is a type of congenital neuromuscular disease affecting anterior horn cells of the brainstem and spinal cord.

The condition typically affects young children. Presents with progressive proximal predominant muscle wasting and weakness of varying severity. Lower extremities can have greater involvement.

SMA can be classified into four types 3:


Inherited as an autosomal recessive form which mutations to SMN1 (survival motor neurone 1) gene on chromosome 5 3.


Shows wasting of musculature. Mild types tend to demonstrate fatty infiltration of muscular bundles with increased intramuscular fat planes 1. Intermediate forms may show ragged atrophy of muscles while the severe forms often show gross atrophy. 

Treatment is mainly supportive. Carries a poor prognosis. Overall length of survival depends on type.

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Article Information

rID: 10154
Section: Pathology
Synonyms or Alternate Spellings:
  • Spinal muscular atrophy (SMA)

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Cases and Figures

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    SMA : age 10 yrs
    Case 1: type 2, age 10 yrs
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    SMA : age 12 yrs
    Case 1: type 2, age 12 yrs
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