MAPT and tauopathy: It has been proposed that the H1 haplotype, one of two common genetic variations at the MAPT locus, may be related to the occurrence of “pure” tauopathy and may be linked to elevated amounts of tau in plasma [72, 393] and synucleinopathies [170, 492], whereas the alternate H2 haplotype correlates with reduced expression of tau protein and thus may have a protective effect [501].