Phase 1 Trial: Natural History Comparison 9 Compared to well-characterized natural history 100% of SMA Type 2 children will never walk without support 95% of children will never stand without assistance More than 30% will die by 25 years of age COHORT: PATIENTS LESS THAN 24 MONTHS OF AGE Compared to well-characterized natural history These patients experienced a mean change of =-0.33 points (standard deviation =4.07) over 12 months Suggests minimal change over a 12-month interval in natural history populations COHORT: PATIENTS BETWEEN 24 AND 60 MONTHS OF AGE The study cohorts will be compared to eligibility-matched, patient-level data drawn from the Pediatric Neuromuscular Clinical Research Network (PNCR) that mirrors the well-characterized natural history WELL-CHARACTERIZED NATURAL HISTORY COMPARISON Kaufman et al. Prospective cohort study of spinal muscular atrophy types 2 and 3; Neurology. 2012 Oct 30; 79(18): 18891897. Mercuri et al. Patterns of disease progression in type 2 and 3 SMA: Implications for clinical trials; Neuromuscular Disorders. 2016 Feb; 26(2): 126-31.