Although both radioligand classes showed binding to 4R non-AD tau in brain of patients with corticobasal degeneration or progressive supranuclear palsy in vivo (Josephs et al., 2016; Hammes et al., 2017; Smith et al., 2017), and likewise to post mortem examination (Josephs et al., 2016; Kikuchi et al., 2016), other studies did not find significant binding in 4R-tauopathies, e.g., using 18F-T807 (Coakeley et al., 2016; Marquie et al., 2017). This evidence concerns the gene MAPT and tauopathy.