Three approved therapies for the treatment of SMA are currently available: nusinersen, a 2-O-methoxyethyl phosphorothioate-modified antisense oligonucleotide that modifies the splicing of the SMN2 pre-mRNA, increasing the production of full-length SMN protein from the SMN2 gene; onasemnogene abeparvovec (AVXS-101), a gene replacement therapy; and risdiplam, an orally administered small-molecule SMN2 splicing modifier that was recently approved by the Food and Drug Administration for the treatment of SMA in adults and children (2 months of age and older). The gene discussed is SMN2; the disease is proximal spinal muscular atrophy.