MAPT and Alzheimer disease: There are now a number of tau PET tracers available for research purposes.9 The most widely used tracer, [18F]flortaucipir, has been shown to reliably detect tau as assessed by neuropathology10,11,12,13 and has been approved by the US Food and Drug Administration for use in the US as a diagnostic marker of neurofibrillary tau in AD.14 It is expected that tau PET will also be available for clinical use in other parts of the world within the coming years.