Even though the NTA and NTB t-tau still need to be further optimized and validated for blood, our findings (together with the earlier reports on NT1 and NT2) support the view that assays targeting minimal N-terminal sequences (including aa 6 targeted by the Tau12 and 1–100 antibodies) provide superior performance in detecting Alzheimer’s disease-relevant tau species in plasma when compared with assays targeting longer N-terminal or mid-region fragments. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.