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Spinal Muscular Atrophy

SMA is a genetic neuromuscular condition. Cells in the spinal cord are damaged, which result in a generalised muscle weakness and can cause respiratory and nutrition complications. 1 in 40 of the UK population are thought to be carriers of the gene that causes SMA.


There are 4 types of SMA, ranging in severity. Type (1) being the most severe and Type (4) being the least severe.


Type 1 (Severe)

Also know as Werdnig-Hoffman syndrome. Onset before or shortly after birth. The child is unable to sit. Does not usually survive past 2 years old.

Type II (Intermediate)

Onset between 3 months and 2 years. The child is able to sit, but not stand without aid. Survival into adulthood possible.

Type III (mild)

Also known as Kugelberg-Welander disease. The onset is usually around 2 years. Able to walk. The child has a normal lifespan.

Adult Onset SMA

Number of forms differing in age of onset. Degree of weakness is variable.

Maxwell has Type II

For more information on SMA, you can visit www.jtsma.org.uk which is the UK’s leading charity for the disease.