C9orf72 and amyotrophic lateral sclerosis: ALS has two types: familial ALS (fALS) caused by genetic mutations, including superoxidase dismutase 1 (SOD1), alsin, senataxin, angiogenin, VAMP-associated protein B, dynactin, transactive response (TAR) DNA-binding protein 43 (TDP43), fused in sarcoma (FUS) and C9ORF72; and sporadic ALS (sALS), which includes ninety percent of all ALS cases and is induced by various environmental and genetic factors.