SMN2 and proximal spinal muscular atrophy: The three currently available FDA-approved therapies for SMA are (1) the gene therapy Onasemnogene abeparvovec (sold under brand name Zolgensma®) that delivers to the cells functional SMN1 gene via the adeno associated virus vector; (2) the antisense oligonucleotide (ASO) Nusinersen (sold under brand name Spinraza®) that, via displacing splicing repressors hnRNPA1/A2 from their binding site, increases the levels of mRNA with exon 7 produced from SMN2; and (3) the small molecule SMN2 splicing modifier Risdiplam (sold under brand name Evrysdi®).