AAV gene therapy of the spinal cord is now FDA-approved for the treatment of infantile Spinal Muscular Atrophy (SMA) with a single IV dose of 2 × 1014 vector genome per kg (vg/kg) of the scAAV9 encoding the Survival Motor Neuron 1 (SMN1) gene [8]. The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.