MAPT and Alzheimer disease: Moreover, filaments in CTE have distinct protofilament interfaces to those of AD [10] The distinct conformations of tau filaments in different tauopathies may not only explain the phenotypic and neuropathologic diversity of these disorders but also underlie the differential affinity of PET ligands, like [18F]-AV-1451, for tau aggregates in AD and non-AD tauopathies.