Using an acetylation-specific tau antibody recognizing residue K280, tau lesions were readily detected in all 4R-tauopathies analyzed including AD, corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), and a panel of familial AD cases, but not 3R-tau predominant Pick’s disease (PD) lacking exon 10 that harbors the K280 residue4. The gene discussed is MAPT; the disease is frontotemporal dementia.