MAPT and tauopathy: The isoform components of misfolded tau conformers vary in different tauopathies [72], and even though AD belongs to 3R/4R secondary tauopathy [73], the 3R- and 4R-tau isoforms are not equally represented in misfolded tau aggregates from human AD brains, of which the content of 4R-isoforms is approximately four-times higher than 3R-tau isoforms in misfolded tau conformers (Table 3) [17].