MAPT and Alzheimer disease: AD is most commonly seen in elderly people and is associated with the formation of intracellular tangles of hyperphosphorylated tau and formation of plaques by beta-amyloid peptides, due to the cleavage of amyloid precursor proteins by beta and gamma-secretase which has a core dimer of Presenilin 1 and 2 (PS1, PS2) [181].