A Study of Risdiplam in Infants With Genetically Diagnosed and Presymptomatic Spinal Muscular Atrophy

Inclusion Criteria: * Males and females aged from birth (1 day) to 6 weeks (42 days) of age at the time of first dose (Day 1); a minimum age of 7 days at first dose is required for the first infant to be enrolled * Gestational age of 37-42 weeks for singleton births; gestational age of 34-42 weeks for twins * Body weight \>= 3rd percentile for age, using appropriate country-specific guidelines * Genetic diagnosis of 5q-autosomal recessive SMA, including confirmation of homozygous deletion or compound heterozygosity predictive of loss of function of the SMN1 gene * Absence of clinical signs or symptoms at screening (Day -42 to Day -2) or at baseline (Day -1) that are, in the opinion of the investigator, strongly suggestive of SMA * Receiving adequate nutrition and hydration at the time of screening, in the opinion of the investigator * Adequately recovered from any acute illness at baseline and considered well enough to participate in the study, in the opinion of the investigator * Able and expected to be able to safely travel to the study site for the entire duration of the study and in accordance to the frequency of required study visits, in the opinion of the investigator * Able to complete all study procedures, measurements, and visits, and the parent (or caregiver), in the opinion of the investigator, has adequately supportive psychosocial circumstances * Parent (or caregiver) is willing to consider nasogastric, naso-jejunal, or gastrostomy tube placement during the stud…