SMN2 and spinal muscular atrophy, type 1: Phase 3, open-label, single-arm, single-dose study of Zolgensma in patients with SMA Type 1 who were either symptomatic or pre-symptomatic with no functional SMN1 gene and 1 or 2 copies of SMN2 and who are <6 months (<180 days) of age at the time of gene replacement therapy (Day 1)