A preclinical proof-of-principal study using SMNΔ7 (Smn−/−, SMN2+/+, SMNΔ7+/+) mice, a mouse model of severe SMA, achieved increased SMN protein levels in spinal motor neurons via single intracerebroventricular (i.c.v.)administration of nusinersen. The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.