SMA, the most common early-onset degenerative neuromuscular disease, is caused in 95% of patients by a loss of the SMN1 gene, which encodes a protein with chaperone functions essential for the assembly of both nuclear and cytoplasmic ribonucleoprotein (RNP) complexes [6, 7]. The gene discussed is SMN1; the disease is proximal spinal muscular atrophy.