MAPT and Alzheimer disease: Beside neurofilament light chain, both the amyloid-b (Ab) peptide as well as hyperphosphorylated forms of the microtubule-associated protein tau play an important role as biomarkers, as senile plaques consisting of aggregated Ab-peptides and neurofibrillary tangles which consist of hyperphosphorylated tau proteins represent the main histopathological hallmarks of AD (4, 5).