Currently, the most promising blood biomarkers for detecting AD are the phosphorylated tau species (p-tau)1,2,3,4,5,6 and amyloid-β 42/40 (Aβ42/40) ratio.7,8,9,10,11,12 However, it is still desirable to have more sensitive blood biomarkers for preclinical AD. Here, MAPT is linked to Alzheimer disease.