Scotland introduces newborn screening for spinal muscular atrophy

The Scottish Government has launched newborn screening for spinal muscular atrophy (SMA), allowing earlier diagnosis and access to potentially life-changing treatment.

SMA is a rare genetic condition causing progressive muscle weakness, affecting breathing, swallowing and movement. Detecting SMA before symptoms appear allows treatment before motor neuron cells are irreversibly damaged. A two-year pilot study, rolled out across the whole of Scotland, will evaluate the early detection of SMA using the existing blood spot test taken around four days after birth.

'SMA can have devastating implications for babies and their families,' said Neil Gray, cabinet secretary for health and social care. 'By detecting SMA before symptoms develop, screening could allow earlier treatment which could be life-changing and help secure the best possible care and support for babies and families'.

About four babies are born with SMA in the UK every month. In about 95 percent of affected individuals, the disease is due to a homozygous deletion of both alleles of the SMN1 gene. Approximately one in 40 people carry a single SMN1 deletion, however one working copy of the gene is usually sufficient enough to produce enough SMN protein to maintain motor neuron function.

SMA causes degeneration of motor neurons in the spinal cord, which disrupts how muscles receive signals from the brain and leads to their atrophy. The disease is typically classified into five clinical types based on when symptoms appear and which physical milestones are achieved. Type 1, the most common, presents between birth and six months of age. Early detection is critical as available treatments can only prevent, not reverse, motor neuron loss, allowing children to reach near-typical developmental milestones.

Giles Lomax, CEO of the charity SMA UK said: 'The future for anyone diagnosed with SMA [now] is very different compared to their peers who were diagnosed symptomatically. These babies will now have the opportunity to grow up without life-long health care needs and the complexity and challenges of living with SMA.

Newborn screening for SMA is part of Genomics England's Generation Study, a wider programme which also aims to sequence the whole genomes of 100,000 newborns to identify treatable rare genetic conditions (see BioNews 1172, 1259, 1262 and 1312).

However, the UK National Screening Committee does not currently recommend SMA screening in England, Wales or Northern Ireland after a 2023 review concluded that evidence on its cost-effectiveness is currently insufficient. SMA UK, clinicians and patients continue to campaign for its inclusion on the newborn screening programme.