Before the new drugs for 5q SMA were developed, clinicians studied the effects of SMA on people. This is called the ‘natural history’ > of the condition. It was different for each ‘Type’ of SMA.

The symptoms and effects of SMA Type 4 begin in adulthood.

Each person is affected differently but, in general, symptoms can include:

• tired, aching muscles
• a feeling of heaviness
• numbness
• cramp
• a slight shaking of the fingers and hands
• fatigue

SMA Type 4 usually progresses slowly over time. It causes increased muscle weakness with age. This may impact on daily living activities, such as walking, dressing and bathing.

SMA Type 4:

• rarely affects swallowing or breathing
• does not affect intelligence
• life expectancy is not affected¹.

SMA Type 4 affects the lower motor neurons. This is different from Motor Neurone Disease (MND), also known as Amyotrophic Lateral Sclerosis (ALS) which affects both the upper and lower motor neurons. Though SMA is also classed as a ‘motor neuron disease’, it is not MND. Whereas MND is almost always life-limiting, SMA Type 4 is not.

England, Wales & Northern Ireland

On 14th May 2026, the National Institute of Health and Care Excellence (NICE) made new recommendations about access to the disease-modifying treatment (DMT) nusinersen. NHS England is now implementing this. Wales and Northern Ireland usually follow NICE guidance.

Nusinersen could now be prescribed to an adult who has SMA Type 4.  Anyone with this diagnosis who wishes to discuss the potential risks and benefits of nusinersen treatment  for them should do so with their clinician.

The other disease-modifying treatment, risdiplam, is only licenced for those diagnosed with SMA Type 1, 2 or 3.

Scotland

Scotland has a different system. Both nusinersen and risdiplam are only funded for SMA Types 1, 2 or 3.

If you have SMA Type 4 and live in Scotland, talk to your clinician about the risks and benefits of nusinersen treatment. This discussion would include whether it would be possible to be funded to travel regularly to a Centre in England for treatment.

Support and advice can help manage the symptoms and effects of SMA Type 4. Nationally and internationally expert clinicians, researchers and people living with SMA are working together to review and update guidelines for best supportive care and management of symptoms for all those  who have 5q SMA – children, teenagers and adults.

• Adult Onset SMA – Diagnosis & Care >
• Living With SMA – information and ideas for daily living >
• The Genetics of 5q SMA >
• Drug treatments for adults who have 5q SMA >
• Regional Neuromuscular Centres (RNMCs) providing treatment >

1. Lunn MR & Wang CH (2008) Spinal muscular atrophy. Lancet, 371: 2120-2133