Gene Replacement Therapy Clinical Trial for Participants With Spinal Muscular Atrophy Type 1

Inclusion Criteria: * Participants with SMA Type 1 as determined by the following features: a. Diagnosis of SMA based on gene mutation analysis with bi-allelic SMN1 mutations (deletion or point mutations) and 1 or 2 copies of SMN2 (inclusive of the known SMN2 gene modifier mutation (c.859G\>C))2 * The first 3 participants enrolled must meet the criteria for the Intent-To-Treat Population * Participants must be \< 6 months (\< 180 days) of age at the time of onasemnogene abeparvovec-xioi infusion * Participants must have a swallowing evaluation test performed prior to administration of gene replacement therapy * Up-to-date on childhood vaccinations. Seasonal vaccinations 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 * Parent(s)/legal guardian(s) willing and able to complete the informed consent process and comply with study procedures and visit schedule Exclusion Criteria: * Previous, planned or expected scoliosis repair surgery/procedure during the study assessment period * Pulse oximetry \< 96% saturation at screening while the participant is awake or asleep without any supplemental oxygen or respiratory support, or for altitudes \> 1000 m, oxygen saturation \< 92% awake or asleep without any supplemental oxygen or respiratory support Pulse oximetry saturation may decrease to \< 96% after screening provided that the saturation does …