Since mutations in SOD1, which encodes superoxide dismutase 1 (SOD1), were first discovered to cause ALS in 1993 (Rosen et al., 1993), at least 27 genes have been found to be definitively associated with familial ALS, including transactive response DNA binding protein (TARDBP), fused in sarcoma (FUS) and chromosome 9 open reading frame 72 (C9ORF72; Chia et al., 2018). This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.