SMN2 and proximal spinal muscular atrophy: Considering that peripheral delivery of nusinersen reaches the CNS before postnatal maturation of the murine blood-brain barrier (BBB) and strongly rescues a severe SMA mouse model (25,26), we focused on subcutaneous (SC) administration in neonate mice and comprehensively assessed the effects of the two ASOs on SMN2 splicing in various tissues and on phenotypic rescue.