C9orf72 and frontotemporal dementia: The overlap of ALS and FTD is further backed up by recent findings in genetics, in particular by the detection of mutations in the TARDP-gene coding for TDP-43 and, more importantly, of hexanucleotide expansions in the C9ORF72 gene as causal for ALS and FTD (DeJesus-Hernandez et al., 2011; Renton et al., 2011; Al-Chalabi et al., 2012; Robberecht and Philips, 2013).