ATXN2 and amyotrophic lateral sclerosis: Other mutations include TAR DNA binding protein (TARDBP), fused in sarcoma (FUS), superoxide dismutase-1 (SOD1) and, less commonly, mutations affecting other proteins like optineurin (OPTN), ubiquilin-2 (UBQLN2) and ataxin-2 (ATXN2) and recently TANK-binding kinase 1 (TBK1) play a role in some familial cases of ALS [19,20].