MAPT and Alzheimer disease: For instance, in Alzheimer's disease (AD) several microRNAs can target key genes involved in the production of amyloid-beta (Aβ), inflammation and defects of neurotransmission: miR-124 targets Aβ-cleaving enzyme 1 BACE1 thus preventing Aβ formation, while downregulation of miR-15a promotes tau hyperphosphorylation (24, 25).