Our study included individuals with Alzheimer's disease (AD), various non-AD tauopathies, and a case of FTLD-TDP-43 type A. In AD, Flortaucipir signal showed a significant but moderate correlation with histological tau pathology, suggesting that while tau is a major contributor, other biological factors also influence Flortaucipir binding in AD. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.