This is an open-label, single-arm, multicenter clinical study to evaluate the effectiveness and safety of risdiplam administered in pediatric participants with SMA and 2 SMN2 copies who previously received onasemnogene abeparvovec and experience a plateau or decline in function. Participants to be enrolled are children \<2 years of age genetically diagnosed with SMA.
<2 years of age at the time of informed consent
Confirmed diagnosis of 5q-autosomal recessive SMA, including genetic confirmation of homozygous deletion or compound heterozygosity predictive of loss of function of the Survival of Motor Neuron 1 (SMN1) gene
Confirmed presence of two SMN2 gene copies as documented through laboratory testing
Administration of onasemnogene abeparvovec pre-symptomatically or post-symptomatically
Previous or current enrolment in investigational study prior to initiation of study treatment
Any unresolved standard-of-care laboratory abnormalities per the onasemnogene abeparvovec prescribing information
Concomitant or previous administration of an SMN2-targeting antisense oligonucleotide
Concomitant or previous use of an anti-myostatin agent