MAPT and Alzheimer disease: Although the aetiology of AD is still debated, the most studied pathogenic mechanism has been the “amyloid cascade hypothesis” proposed in 1991 by Hardy and Allsop, who suggested that inappropriate processing of amyloid-β (Aβ) precursor leads to the build-up of amyloid plaques, the formation of tau tangles, and ultimately to neuronal death [7].