C9orf72 and amyotrophic lateral sclerosis: Mutations in more than 30 genes have been identified to cause ALS, including SOD1, TARDBP, FUS, and C9orf72. Approximately 50–70% of ALS patients with a family history of the disease can be attributed to mutations in these genes; however, these mutations are found in only 3% of the Japanese patients with sporadic ALS2.