Among the extensively studied plasma biomarkers for Alzheimer’s disease, notable candidates include Aβ1–42, the Aβ1–42/Aβ1–40 ratio,6 tau proteins with phosphorylation at amino-acid positions 181, 217 and 231 (pTau-181, pTau-217 and pTau-231). Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.