C9orf72 and frontotemporal dementia: This continuum has been reinforced on two levels: i) pathological - TAR DNA binding protein 43 kD (TDP-43) is the principal protein inclusion in ALS and in a subgroup of FTD cases [9], [10]; and recently ii) genetic – by identifying a unique expansion in the intron of C9ORF72 on chromosome 9 (9p21) in families affected by ALS, FTD or ALS-FTD.