Onasemnogene‐abeparvovec administration to premature infants with spinal muscular atrophy

Abstract Twin girls born at 30 weeks' gestation with spinal muscular atrophy (SMA) received onsasemnogene‐abeparvovec (OA) at 3.5 weeks of life. They had no treatment‐related adverse events, normal acquisition of motor milestones, and normal neurological examination at 19 months. Genotyping revealed 0 copies of SMN1 and a single, hybrid SMN2 gene containing the positive genetic modifier c.835‐44A>G. This was associated with full‐length SMN2 blood mRNA expression levels similar to a 2 copy SMA infant. The observed favorable outcomes are likely due to the genetic modifier combined with early drug administration enabled by prematurity.