Intravenous injection of self-complementary serotype 9 adeno-associated virus vectors expressing SMN1 mRNA on postnatal day 1 successfully rescued neuromuscular function and life span in SMA mice (Smn−/−SMN2+/+SMNΔ7+/+), while injections on postnatal days 5 and 10 resulted in partial correction and little effect, respectively (13). Here, SMN2 is linked to proximal spinal muscular atrophy.