MAPT and Alzheimer disease: Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by amyloidopathy (lower levels of amyloid beta [Aβ] 42 or lower ratio of Aβ42 to Aβ40) and tauopathy (elevated levels of phosphorylated tau [pTau]) in the cerebrospinal fluid (CSF)) [1,2,3].