MAPT and Alzheimer disease: In the biological context, two main etiological effectors have been identified for AD: (i) Neurofibrillary tangles (NFT), derived from the progressive aggregation of the hyperphosphorylated protein tau inside the neurons, assembled in oligomeric structures referred to as paired helical filaments (PHF) [5,6,7,8]; and (ii) senile plaques (SP) formed by deposits of the amyloid-β (Aβ) peptide (39 to 42 aminoacidic residues).