Analyses of fALS have revealed the causative genes of ALS such as TARDBP (which encodes TDP-43), SOD1, FUS, C9ORF72, ATXN2, OPTN, VCP, UBQLN2, UBQLN4, SQSTM1, TBK1, and so on, but the mechanism of ALS onset has remained elusive. This evidence concerns the gene ATXN2 and amyotrophic lateral sclerosis.