MAPT and Alzheimer disease: Molecularly, AD presents a multifactorial etiology, in which genetic and environmental factors contribute to the formation of senile amyloid plaques, composed of amyloid beta (Aβ) fibrils, and intracellular neurofibrillary tangles (primarily characterized by the abnormal accumulation of the microtubule-associated tau protein, which is hyperphosphorylated) in different brain areas [4].