MAPT and Alzheimer disease: Currently, CSF biomarkers are formally integrated into diagnostic criteria for AD (Aβ1-42 peptide, total tau (t-tau), and phosphorylated-tau (p-tau) proteins) and Creutzfeldt–Jakob Disease (CJD) (the detection of prion protein (PrP) scrapie using the real-time quaking-induced conversion assay (RT-QuIC)) [9,20,21,22].