Baseline characterisation of adults living with spinal muscular atrophy in the UK: insight from the Adult SMA REACH Real-World Data Collection Study.

Spinal Muscular Atrophy (SMA) is a rare, inherited neuromuscular disease affecting infants to adults. 5q-SMA is primarily caused by a homozygous deletion of exon 7/8 in the SMN1 gene. The disease is classified into 5 subtypes (SMA type 0-4) based on the age of disease onset and highest level of motor function attained. However, knowledge about the adult SMA population and the natural progression of the disease in this group remains limited. To address this gap and gain a comprehensive understanding of the natural history of SMA in the UK, the Adult SMA REACH data collection study was launched in 2020. This study supports the implementation and approval process of disease-modifying therapies for adults living with SMA - further information can be found from ClinicalTrials.gov with trial identifier NCT06978985, (https://clinicaltrials.gov/study/NCT06978985). Adult SMA REACH study collected data nationally from 19 sites over a period of four years. In this report, we present baseline data from 376 adults with SMA, captured before or at the initiation of treatment as part of the Adult SMA REACH study. We here characterise the cohort by SMA type and functional status at treatment onset using demographics and a series of functional outcome measures used in SMA.