SMN1 and spinal muscular atrophy, type II: Genetic SMN-modulating or replacement therapies (i.e. nusinersen, risdiplam and onasemnogene abeparvovec) improve survival in patients with SMA type 1 and motor function in patients with SMA types 1–3, but their effects on fatigability are unclear.8–15 A post hoc analysis of fourteen patients with SMA types 2 and 3 suggested a possible beneficial effect of nusinersen on fatigability.55 Additional, larger studies are still needed to assess the effects of genetic therapies on fatigability and NMJ function.