A Study Evaluating the Effectiveness and Safety of Risdiplam Administered as an Early Intervention in Pediatric Participants With Spinal Muscular Atrophy After Gene Therapy

Inclusion Criteria:

• <2 years of age at the time of informed consent

• Confirmed diagnosis of 5q-autosomal recessive SMA

• Confirmed presence of two SMN2 gene copies

• Administration of onasemnogene abeparvovec pre-symptomatically orpost-symptomatically

• Has received onasemnogene abeparvovec for SMA no less than 3 months, but not morethan 7 months, prior to enrollment

• Has, in the opinion of the investigator, not experienced clinically significantdecline in function from the time of onasemnogene abeparvovec administration

Exclusion Criteria:

• Treatment with investigational therapy prior to initiation of study treatment

• Any unresolved standard-of-care laboratory abnormalities per the onasemnogeneabeparvovec prescribing information

• Concomitant or previous administration of a SMN2-targeting antisense oligonucleotideor SMN2 splicing modifier either in a clinical study or as part of medical care

• Requiring invasive ventilation or tracheostomy

• Requiring awake non-invasive ventilation or with awake hypoxemia (SaO2 <95%) with orwithout ventilator support

• Presence of feeding tube and an OrSAT score of 0

• Hospitalization for pulmonary event within the last 2 months, or any plannedhospitalization at the time of screening

• Any major illness requiring hospitalization within 1 month before the screeningexamination or any febrile illness within 1 week prior to screening and up to firstdose administration.