Spinal Muscular Atrophy (SMA) | Symptoms and Causes

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What are the symptoms of spinal muscular atrophy?

Symptoms of spinal muscular atrophy (SMA) vary greatly depending on the type. Children with more severe forms of SMA usually have more severe symptoms that are noticeable within the first six months of life. Those with milder forms have less severe symptoms that may not be noticeable until the child is 18 months or older.

Symptoms of SMA may include:

  • muscle weakness and decreased muscle tone
  • limited mobility
  • breathing problems
  • problems eating and swallowing
  • delayed gross motor skills
  • spontaneous tongue movements
  • scoliosis (curvature of the spine)

What are the causes of spinal muscular atrophy?

SMA is an autosomal recessive disease. This means that (most of the time) both parents must carry the genetic mutation for a child to have the condition.

The gene affected in SMA is the “survival of motor neuron” gene (SMN1 and 2). In 95 percent of SMA cases, both copies of the SMN1 gene are missing.

If someone in your family has SMA, your chance of being an SMA carrier significantly increases. When both parents are carriers, there is a one in four (25 percent) chance with each pregnancy that they will have a child with SMA.

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