MAPT and early-onset autosomal dominant Alzheimer disease: Flortaucipir (previously 18F-T807; 18F-AV-1451) is currently approved by the U.S. Food and Drug Administration (FDA) as TauvidTM: ‘a radioactive diagnostic agent indicated for PET imaging of the brain to estimate the density and distribution of aggregated tau neurofibrillary tangles (NFTs) in adult patients with cognitive impairment who are being evaluated for Alzheimer’s disease.’9 It was the first tau PET tracer to be introduced and has been widely adopted and validated in several research and clinical settings.