The 20 cases with a negative [18F]flutemetamol PET were either normal (n = 7) or had a non-AD dementia (Lewy body disease (n = 3), vascular dementia (n = 6), neurofibrillary predominant dementia (n = 1), argyrophilic grain disease (n = 1), progressive supranuclear palsy (n = 1), and frontotemporal lobar degeneration with TDP-43 pathology (FTLD-TDP) (n = 1)). The gene discussed is TARDBP; the disease is Classical progressive supranuclear palsy.