The most common genetic causes of ALS are pathogenic rare missense mutations in the superoxide dismutase 1 (SOD1), fused in sarcoma (FUS), and TAR DNA-binding protein 43 (TARDBP) genes, as well as hexanucleotide repeat expansions in the chromosome 9 open reading frame 72 (C9ORF72) gene. Here, SOD1 is linked to amyotrophic lateral sclerosis.