For example, a study employed a scAA9 vector carrying an endogenous human survival motor neuron 1 (SMN1) promoter to drive SMN1 expression specifically in neurons.115 This approach demonstrated a remarkable safety profile, notably decreasing liver toxicity, and enhanced therapeutic efficacy in the SMNdelta7 mice with spinal muscular atrophy (SMA). The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.