MAPT and early-onset autosomal dominant Alzheimer disease: We recently developed a positron emission tomography (PET) probe, [18F]PM‐PBB3, to detect tau lesions in diverse tauopathies, including mixed three‐repeat and four‐repeat (3R + 4R) tau fibrils in Alzheimer's disease (AD) and 4R tau aggregates in progressive supranuclear palsy (PSP).