Intravenous onasemnogene abeparvovec efficacy and safety were demonstrated in one Phase I and two Phase III studies that included symptomatic SMA type 1 patients with two SMN2 copies [14–17], and a Phase III study that included presymptomatic infants at risk of developing SMA with two or three SMN2 copies [18, 19]. This evidence concerns the gene SMN2 and proximal spinal muscular atrophy.