• You can find out more about SMA Types 1, 2, 3 and 4 here: What is SMA?

There are four main types of SMA:

  • SMA Type 1: Symptoms usually begin between 0 and 6 months.
  • SMA Type 2: Symptoms usually appear between 7 and 18 months of age.
  • SMA Type 3: There are two types of SMA Type 3:
  • – SMA Type 3a: Symptoms usually begin between 18 months and 3 years of age.

    – SMA Type 3b: Symptoms will usually begin after 3 years of age.

  • SMA Type 4: Symptoms begin in adulthood.

You can find out more about the symptoms, diagnosis and the effects of all types of SMA in this factsheet

Our thanks to Spinal Muscular Atrophy Support UK (SMA Support UK), a certified member of The Information Standard, who have produced these factsheets. Muscular Dystrophy UK works closely with SMA Support UK and endorses the information provided in the above factsheets.

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