The authors showed that a mild increase in Flortaucipir-PET binding was not a reliable indicator of FTLD-tau pathology: such signal was observed in patients with underlying 4R tau pathology (PSP, CBD) but also in a patient with bvFTD and underlying TDP-A pathology due to a GRN mutation. This evidence concerns the gene GRN and supranuclear palsy, progressive, 1.