We will conduct a longitudinal cohort study in patients with SMA to analyse the use of an integrated set of well-established and more recently developed electrophysiological techniques – the ‘SMA Motor Map’ – to 1) provide further insight into the pathophysiology of SMA and 2) investigate its value as a biomarker to predict clinical response after treatment with SMN2-splicing modifying therapies nusinersen or risdiplam. This evidence concerns the gene SMN2 and proximal spinal muscular atrophy.