MAPT and Alzheimer disease: Besides atrophy and neuronal as well as synaptic loss, there are two pathologic hallmarks of Alzheimer’s disease (AD): extracellular accumulation of amyloid beta peptide in the form of amyloid plaques and hyperphosphorylation of tau protein which polymerizes in the form of paired helical filaments, the key component of intraneuronal neurofibrillary tangles [1].