More than 20 causative genes and proteins, including TAR DNA-binding protein 43 (TDP-43), fused in sarcoma (FUS), C9orf72, and ataxin-2, have been identified by recent genetic analysis of ALS patients and pathological examination of patient’s neurons, and these genes and proteins have been extensively investigated in terms of the pathology of ALS [4,5,6,7,8,9,10,11]. The gene discussed is C9orf72; the disease is amyotrophic lateral sclerosis.