MAPT and early-onset autosomal dominant Alzheimer disease: The main hallmark of Alzheimer’s disease (AD) is the accumulation of plaques of amyloid β (Aβ) peptide and neurofibrillary tangle aggregates of hyperphosphorylated, misfolded tau protein, causing an adverse effect on neuronal functions and eventually leading to their degeneration and progressive cognitive impairment [1].