SOD1 and amyotrophic lateral sclerosis: Over 20 genes have been identified and/or implicated so far in ALS, with the most common mutations involving the genes encoding for superoxide dismutase 1 (SOD1), TAR DNA-binding protein (TARDBP), fused in sarcoma (FUS), and chromosome 9 open reading frame 72 (C9orf72) [8].