An operational framework, called ATN from the biological markers of (A)myloid-β, (T)au and (N)eurodegeneration, has facilitated a transition from a clinical perspective to a biological viewpoint of Alzheimer’s disease, decoupling diagnosis from discrete clinical stages.2,23 Classification into ATN stages requires the designation of individuals as Aβ, tau and neurodegeneration positive or negative. This evidence concerns the gene MAPT and early-onset autosomal dominant Alzheimer disease.