The first generation of tau PET tracers, including THK family compounds and AV-1451 (also known as T807, flortaucipir), has been widely explored in vivo in AD patients, and its effects have been compared with those in controls; this has generated important information about the progression of tau pathology and its relation to functional changes in patients (see reviews [5–7]). This evidence concerns the gene MAPT and Alzheimer disease.