Study of Intrathecal Administration of Onasemnogene Abeparvovec-xioi for Spinal Muscular Atrophy

Key Inclusion Criteria * Patients ≥6 months and up to 60 months (1800 days) of age at time of dosing following diagnostic confirmation during screening period by genotype who demonstrate the ability to sit unassisted for 10 or more seconds but cannot stand or walk * Diagnostic confirmation by genotype includes lab documentation of homozygous absence of SMN1 exon 7; with exactly three copies of SMN2 * Negative gene testing for SMN2 gene modifier mutation (c.859G\>C) * Onset of clinical signs and symptoms consistent with spinal muscular atrophy (SMA) at \< 12 months of age * Able to sit independently and not standing or walking independently. Definition of sitting independently is defined by the World Health Organization Multicentre Growth Reference Study (WHO-MGRS) criteria of being able to sit up unsupported with head erect for at least 10 seconds. Child should not use arms or hands to balance body or support position (Wijnhoven 2004) * Be up-to-date on childhood vaccines that include palivizumab prophylaxis (also known as Synagis) to prevent respiratory syncytial virus (RSV) infections are also recommended in accordance with American Academy of Pediatrics (AAP 2009) Key Exclusion Criteria * Current or historical ability to stand or walk independently * Contraindications for spinal tap procedure or administration of intrathecal therapy or presence of an implanted shunt for the drainage of CSF or an implanted central venous (CNS) catheter * Severe contractures as determined…