MAPT and Alzheimer disease: Studies have shown that the levels of amyloid-β 1-42 peptide (Aβ42), total tau (T-tau), and tau phosphorylated at threonine 181 (p-tau) in cerebrospinal fluid (CSF) samples can be used as AD diagnostic biomarkers (Shaw et al., 2009; Hampel et al., 2010).