SMN2 and proximal spinal muscular atrophy: The US Food and Drug Administration (FDA) and European Medicines Agency (EMA) have approved three treatment options for SMA, one gene replacement therapy (omasemnogene abeparvovec) and two SMN2 splicing modifiers (nusinersen and risdiplam) (Messina and Sframeli, 2020; Wirth et al., 2020; Dimitrova, 2021).