This study looks at how safe and effective a medicine called risdiplam is for young children with a disease called Spinal Muscular Atrophy (SMA). SMA is a genetic disorder that makes muscles weak. The study is for kids under 2 years old who have SMA and have already been treated with a special gene therapy called onasemnogene abeparvovec. This study is open-label, meaning everyone knows what treatment is given, and single-arm, meaning all participants get the same treatment.

Participants need to have 2 copies of a gene called SMN2, and must have received onasemnogene abeparvovec 3 to 7 months before joining the study. Children who need certain types of breathing support or have other health issues may not be able to join.

• Length of Study: Participation requires regular follow-up visits.
• Eligibility: Only for kids under 2 with specific genetic conditions.
• Risks: Potential risks related to treatment and previous health conditions.