SMN1 and proximal spinal muscular atrophy: The search used a focused set of key terms, including “spinal muscular atrophy,” “SMA,” “exosome,” “extracellular vesicle (EV),” “neuromuscular junction (NMJ),” “axon”, “muscle signaling,” and “SMN deficiency.” Both preclinical, clinical, and translational evidence were included, with additional articles identified through citation tracking.