MAPT and Alzheimer disease: Decreased cerebrospinal fluid (CSF) levels or documentation of plaque deposition of β-amyloid42 (Aβ42), reduced cortical temporo-parietal 18F-fluoro-2-deoxy-d-glucose uptake (18F-FDG) on positron emission tomography (PET), and increased CSF levels of total-tau (t-tau) and phosphorylated-tau (p-tau) have been considered biomarkers of AD neuropathology and are currently used to support AD diagnosis in both clinical practice and research [21–24].