Of note, 81A11 which recognizes R2 of the MTBD of tau does not recognize pathological tau inclusions in PSP brain as well as the other antibodies which recognize R4 and it could be speculated that this epitope is masked due to the amyloidogenic β-sheets forming in this region of tau [21, 33]. This evidence concerns the gene MAPT and supranuclear palsy, progressive, 1.