The first proof of concept for therapeutic ASOs efficacy in preventing aberrant alternative splicing has come from the FDA-approved ASO “Spiranza”, that targets survival motor neuron 2 (SMN2) pre-mRNA to promote exon 7 inclusion and full length SMN2 protein expression and has been successfully employed to treat spinal muscular atrophy [300, 301]. The gene discussed is SMN2; the disease is proximal spinal muscular atrophy.