The discovery of missense mutations in multiple RNA binding proteins, such as fused in sarcoma (FUS) (Kwiatkowski et al., 2009, Vance et al., 2009), transactive response DNA binding protein 43 (TDP-43) (Kabashi et al., 2008, Sreedharan et al., 2008), heterogeneous nuclear ribonucleoprotein (hnRNP) A1 and A2/B1 (Kim et al., 2013), in patients with familial forms of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), has opened up a new and highly productive avenue of research into the pathobiology of ALS and FTD. This evidence concerns the gene FUS and frontotemporal dementia.