Mutations in SOD1, TDP-43 and fused in sarcoma (FUS) causes familial ALS (Rosen et al., 1993; Sreedharan et al., 2008; Kwiatkowski et al., 2009); TDP-43 mutation has also been seen in some familial cases of FTD. The gene discussed is FUS; the disease is frontotemporal dementia.