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Spinal muscular atrophy (SMA) is a genetic condition that affects the nerves in the spine. On this page, you will learn about the different types of SMA and what causes the condition.
Spinal muscular atrophy (SMA) is a rare genetic disorder in which the nerves in the spinal cord slowly become weaker or stop working. This can affect your child’s ability to crawl, walk, eat or breathe.
SMA is caused by a mutation (change) in the SMN1 gene (piece of genetic material). The change causes lower levels of survival motor neuron protein (a protein that helps certain nerves and muscles work properly). Without this protein, nerves in the spine do not work as they should.
A child can inherit SMA in an autosomal recessive manner. This means that he receives 2 copies (one from each parents) of the non-working SMN1 gene to have SMA.
There are 4 different types of SMA:
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