Systematic Literature Review of the Natural History of Spinal Muscular Atrophy: Motor Function, Scoliosis, and Contractures.

Results demonstrate that a high degree of motor function loss is inevitable, affecting patients of all ages. Additionally, data suggest that untreated patients with Types 2 and 3 SMA remain at risk of losing motor milestones during late adulthood, and patients with Types 3a and 3b SMA are at risk of loss of ambulation over time. These findings support the importance of stabilization of motor function development even at older ages. Natural history data are key for the evaluation of SMA treatments as they contextualize the assessment of long-term outcomes.