Differential diagnosis between AD and FTD may be challenging as AD may manifest with behavioral disturbances (the “frontal variant” (Dubois et al., 2014)) whereas, on the other side, memory disturbances may manifest in FTD, particularly in carriers of GRN and chromosome 9 open reading frame (C9orf72) mutations (Galimberti et al., 2015, Pietroboni et al., 2011). This evidence concerns the gene C9orf72 and Alzheimer disease.