In a recent study, plasma NfL showed an AUC of 0.82 for separating clinically diagnosed AD dementia from patients with FTLD syndromes (Thijssen et al, 2021a), and AUCs of 0.97 and 0.96 for distinguishing neuropathologically confirmed AD from neuropathologically confirmed FTLD‐tau and FTLD‐TDP cases, respectively. This evidence concerns the gene MAPT and Alzheimer disease.