Spinal muscular atrophy

Also called SMA

A genetic condition destroying the nerves that drive muscles. New treatments have changed it from fatal to manageable for many.

What it is

Spinal muscular atrophy is caused by a faulty SMN1 gene, which means motor neurones in the spinal cord degenerate. Muscles weaken progressively, and breathing and swallowing are affected in the more severe types.

It affects around 1 in 10,000 births, and around 1 in 40 to 50 people carry the gene without knowing.

This is one of the few entries in this library where the story has recently changed completely. Type 1 SMA was until recently the commonest genetic cause of death in infancy. Three treatments, nusinersen, risdiplam and the gene therapy onasemnogene abeparvovec, are now available on the NHS, and treated early they alter the course dramatically.

Because outcomes depend so heavily on treating before motor neurones are lost, newborn screening for SMA is the subject of active debate in the UK.

Signs you might notice

Type 1, from birth to six months: floppiness, weak cry, difficulty feeding and breathing, tongue fasciculations, and never sitting unaided.

Type 2, from 6 to 18 months: sitting but never walking independently, scoliosis, and respiratory weakness.

Type 3, after 18 months: walking then losing it, frequent falls, difficulty climbing stairs.

Type 4, in adulthood: milder proximal weakness.

Across all types: intellect is entirely unaffected, and sensation is normal.

How it can affect day-to-day life

Respiratory care is the centre of daily management: cough assist, non-invasive ventilation, and treating chest infections aggressively and early. A chest infection is the event most likely to cause deterioration.

Nutrition and swallowing need active management, since dysphagia is common and aspiration is dangerous.

Scoliosis progresses and needs monitoring and often surgery.

Equipment and housing adaptation lead times are long, and anticipating needs a year ahead is what keeps a child in education and a family functioning.

Supporting someone well

Treat chest infections early and aggressively, and have a plan agreed in advance.

Use the cough assist regularly, not only during illness.

Anticipate equipment: order for where the person will be in six months.

Presume competence absolutely. Intellect is unaffected, and children with SMA are frequently underestimated because of their physical presentation.

Ask about treatment eligibility and about newborn screening if there is a family history.

Get genetic counselling; carrier testing matters for the wider family.

Fiducia Guardian holds the respiratory plan, equipment, medicines and the full team, which in SMA spans neurology, respiratory, orthopaedics, dietetics and therapy.

Where to get help

Care should come from a specialist neuromuscular centre.

SMA UK provide family support, equipment grants and information on treatments.

Any respiratory deterioration needs prompt specialist assessment rather than routine care.