SOD1 and amyotrophic lateral sclerosis: Specifically, non-viral gene therapy approaches entered clinical trials for two familial forms of ALS—Cu/Zn superoxide dismutase 1 (SOD1)-linked ALS (NCT02623699 [7,8]) and the most common form of ALS caused by mutations in the chromosome 9 open reading frame 72 (C9orf72) gene (NCT03626012 [9]).