MAPT and Alzheimer disease: Recent advancements in clinical chemistry have enabled precise quantification of AD biomarkers using plasma.5,6,7,8,9 The plasma Aβ42/40 ratio has revealed a promising discriminative performance for detecting Aβ positivity with good to excellent accuracy.10 Additionally, several epitopes of phosphorylated tau (p-tau),11,12,13,14 glial fibrillary acidic protein (GFAP),15,16,17 and neurofilament light chain (NfL)18,19 have been studied as promising plasma biomarkers for downstream AD processes, reflecting tau hyperphosphorylation, astrocytic activation, and neuronal damage, respectively.