C9orf72 and frontotemporal dementia: It is now clear that ALS and FTD can overlap at genetic and pathological level, since genetic mutations in transactive response DNA-binding protein 43 (TARDBP), Fused-in-Sarcoma (FUS) and C9orf72 locus are associated with both disorders (Lomen-Hoerth et al., 2002; Renton et al., 2011; Al-Chalabi et al., 2012).