This clinical trial focuses on the long-term follow-up of patients with Spinal Muscular Atrophy (SMA), a genetic disorder that affects the control of muscle movement. The study involves a treatment called OAV101, also known by its scientific name onasemnogene abeparvovec or its code name AVXS-101. This treatment is administered as a solution for infusion, which means it is given directly into the bloodstream through a vein. The purpose of the study is to assess the long-term safety of this treatment in patients who have previously participated in clinical trials involving OAV101.

Participants in this study will be monitored over an extended period to observe any serious side effects or specific adverse events that may arise from the treatment. The study aims to understand the long-term effects of OAV101 on patients with SMA, focusing on safety aspects. The trial will track the number and proportion of patients experiencing these events throughout the study duration, which can last up to 15 years.

In addition to safety, the study will also look at developmental milestones, which are key skills or abilities that children typically achieve as they grow. Researchers will assess how many participants reach these milestones and whether they maintain them over time. Changes in motor function will be measured using specific scales, such as the Hammersmith Functional Motor Scale – Expanded and the Revised Upper Limb Module. The study will also monitor vital signs and laboratory values to identify any significant changes that could be related to the treatment.