SMN2 and proximal spinal muscular atrophy: In 2019, onasemnogene abeparvovec, a gene therapy applied by a one-time intravenous infusion of an adeno-associated virus vector for SMN1 correction has been approved by the FDA for patients with SMA below 2 years of age with biallelic mutations of the SMN1 gene and up to three copies of the SMN2 gene [9].