Using autoradiography and immunohistochemistry, our study had three main objectives: 1) to evaluate the binding properties of AV-1451 to AD-tau and compare it to several non-AD tauopathies; 2) to evaluate the specificity of AV-1451 binding in disorders not associated with significant tau deposition such as TDP-43 proteinopathies and α-synucleinopathies; and 3) to investigate the nature and patterns of “off-target” AV-1451 binding. This evidence concerns the gene MAPT and synucleinopathy.