SOD1 and amyotrophic lateral sclerosis: Familial ALS (fALS) accounts for approximately 10% of all cases, and its causative gene defects have been identified, including mutations in genes encoding superoxide dismutase 1 (SOD1), fused in sarcoma, TAR DNA-binding protein-43 (TDP-43), optineurin, and C9ORF72 [2].