MAPT and Alzheimer disease: The pathological hallmark of AD includes the presence in the brain of extracellular amyloid plaques (consisting of the 42-amino acid beta-amyloid protein or Aβ; Glenner and Wong, 1984; Masters et al., 1985), neurofibrillary tangles (filaments inside neurons consisting of tau protein; Iqbal et al., 1986; Kosik et al., 1986; Lee et al., 1991), and cerebrovascular amyloid deposits in the walls of blood vessels (containing Aβ 1–40 and 1–42; Pardridge et al., 1987).