10 Key Facts About Spinal Muscular Atrophy

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by Wendy Henderson |

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Spinal muscular atrophy (SMA) is a rare genetic disorder where muscles in the body degenerate over time. It is a regressive disease which can, depending on its severity, lead to being unable to walk, talk, swallow and breathe. Here are some key facts about the disease based on information from the SMA Trust.


SMA is caused by a fault in the Survival Motor Neuron 1 (SMN1) gene.

Better understand the mechanisms of spinal muscular atrophy with this animated film.


Approximately one in 6,000 to 10,000 babies will be born with the condition.

Read about five frequently asked questions about spinal muscular atrophy.


There are four types of SMA, with type 1 being the most severe form and type 4 the mildest form.

Discover more information about the different types of SMA here.


Types 1 to 3 appear in childhood and type 4 SMA appears in adulthood.

Read about the three main symptoms of spinal muscular atrophy.


Type 1 SMA is often diagnosed within a few months of the infant’s life.

Find out about an amazing charity which helps parents of children with type 1 SMA.


Type 2 SMA is usually diagnosed after the age of six months when the infant fails to meet certain development milestones. Advances in medicine and technology mean that they can still live productive lives.

Find out what it’s like living with a degenerative muscular disorder. 


Type 3 SMA can occur later in a child’s life and their motor skills will start to reverse. Although many will need a wheelchair, the life expectancy is normal and they can lead full lives.

Find out more about Assistant Attorney General Steve Mikita who has type 3 SMA.


Type 4 SMA, or adult-onset SMA, is a much milder form of the disease and only slight disability will be experienced.

Discover more about the progression of spinal muscular atrophy.


SMA is an autosomal recessive neurodegenerative disease, which means both parents need to have the faulty gene and the child will receive one copy of the faulty gene from each parent.

Read more about the faulty gene responsible for spinal muscular atrophy here.


It’s estimated that between one in 40 to 60 people are SMA carriers.

Learn about the five steps of diagnosis for spinal muscular atrophy.

SMA News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.