You might have heard or read the words “Spinal Muscular Atrophy” (“SMA”) in any number of broadcasts or publications over the recent weeks, given ex-Little Mix member Jesy Nelson’s recent intimate revelation that her twin babies – born in May 2025 – have been diagnosed with Type 1 of the condition. Jesy is now pushing to raise awareness for SMA and campaigning for the condition to be added to the NHS’s current offering of newborn blood spot (heel prick) screening. The heel prick test is undertaken when a baby is five days old, and screens for 10 rare, serious health conditions. SMA does not currently feature within those ten. But what is SMA?
Spinal Muscular Atrophy: A brief overview
Spinal Muscular Atrophy is a rare genetic neuromuscular condition which causes the progressive wasting (“atrophy”) and therefore weakness of the muscles. Put simply, SMA causes the nerves responsible for activating the muscles to deteriorate. When healthy, the nerves carry signals from the brain to the muscles, enabling them to contract and bring about movement. In somebody affected by SMA however, these nerves are unable to carry signals from the brain to the muscles effectively. This means that the muscles atrophy over time due to their lack of use. Depending on the type of SMA, this can be a relatively quick process which takes place over months as opposed to years. Sadly, the deterioration of the nerves is irreversible.
Types of Spinal Muscular Atrophy
By far the most common type of Spinal Muscular Atrophy is known as 5q SMA, which is caused by a mutation in the SMN1 gene on chromosome 5. 5q SMA can in turn can be separated into five “Types”. These are based on the age at which symptoms of SMA begin and the milestones an individual achieves such as sitting, standing and walking:-
Type 0
- Onset: Pre-birth.
- Symptoms: Extreme muscle weakness, significant respiratory failure.
- Prognosis: Life expectancy limited to a few months.
Type 1
- Onset: 0-6 months.
- Symptoms: Muscle weakness, inability to hold head steady/sit independently, sucking & swallowing challenges, breathing difficulties.
- Prognosis: Without treatment, life expectancy limited to around 24 months.
Type 2
- Onset: 6-17 months.
- Symptoms: Assistance required to reach seated position but sits without support, progressive muscle weakness through childhood, hand tremors, inability to stand/walk independently, weak respiratory muscles.
- Prognosis: ~70% of affected individuals reach their 25th birthday.
Type 3
- Onset: 18 months-17 years.
- Symptoms: Able to stand/walk but may require assistance, progressive difficulty walking with potential for wheelchair use later in life, balance issues, muscle twitches/hand tremors.
- Prognosis: Life expectancy unaffected.
Type 4
- Onset: 18+ years.
- Symptoms: Mild/moderate muscle weakness and fatigue, difficulty walking, muscle twitches/hand tremors.
- Prognosis: Life expectancy unaffected.
Inheritance of Spinal Muscular Atrophy
5q SMA is what is known as an autosomal recessive condition. This means that a person will only be affected by SMA if they inherit two copies of the faulty gene (SMN1) – one from each “carrier” parent.
If a child is born to two carriers, there is a:
- 50% chance they will be born a carrier of SMA;
- 25% chance they will be born completely unaffected;
- 25% chance they will be born affected by SMA.
Approximately 1 in 40 people in the UK are carriers of the faulty SMN1 gene. This equates to there being approximately 1.6 million carriers in the UK.
Treatment for Spinal Muscular Atrophy
There is no cure for Spinal Muscular Atrophy. As of 2019 however, there are several drug treatments that have been approved by the NHS. Whilst not suitable for every person affected by SMA, most sufferers of Type 1, 2 or 3 SMA can receive drug therapy and see a positive impact with regards what motor milestones they go on to achieve. These treatments effectively halt the deterioration of the nerves, meaning the muscles do not continue to atrophy. Starting treatment is therefore time-critical, with the drugs most effective when administered either before the onset or in the early stages of muscle weakness.
This makes prompt diagnosis essential, though, sadly, delays in diagnosis of SMA are not uncommon due to the generalisation of symptoms and their incorrect attribution to mild developmental delay.
How Moore Barlow can help
Should you, your child or someone you know have been affected by a delay in diagnosis of Spinal Muscular Atrophy, or should there have been a failure to genetically screen for SMA despite there being affected individuals or known carriers in your family, our team of expert medical negligence solicitors are here to help.
