C9orf72 and amyotrophic lateral sclerosis: To date, four major genes are known to cover up to 60% of familial forms of ALS and 10–13% of sporadic ALS cases, i.e., SOD1, the chromosome 9 open reading frame 72 (C9orf72), TAR DNA-binding protein (TARDBP) [30, 31], and fused in sarcoma (FUS).