Motor unit gains in treated spinal muscular atrophy patients.

Over the last 5 years, three gene-targeting therapeutics have been approved for spinal muscular atrophy (SMA) including the splice switching oligonucleotide nusinersen in 2016, the gene therapy onasemnogene abepavovec in 2019 and the splice switching small molecule risdiplam in 2020. Although past and ongoing clinical trials demonstrate improvements in motor function scores in treated SMA patients of variable magnitude, the changes of motor neuron structure and function that underlie these clinical outcomes are unknown. In the paper by Kariyawasam et al 1 this knowledge gap is explored in 20 children with symptomatic SMA of various types, who were treated with nusinersen for 1–2 years in the commercial setting and evaluated sequentially with a novel motor unit …