MAPT and Alzheimer disease: Cerebrospinal fluid (CSF) core biomarkers for AD – i.e., amyloid-beta (Aβ) 42/40 ratio, tau phosphorylated at threonine-181 (p-tau), and total-tau (t-tau) – are largely used in clinical settings, research, and drug trials (Paterson et al., 2018; Gaetani et al., 2020).