The similarities of AD and FTLD pathologies in DNA damage and repair or in HMGB1-TLR-PKC pathway prompted us to investigate more comprehensively whether and how common pathomechanisms are shared between the two largest groups of dementia affecting the function and cell death of cerebral neurons together with intracellular7–11,40,42,43 and/or extracellular44 protein aggregations. The gene discussed is PRRT2; the disease is Alzheimer disease.