This precedes the spread of tau aggregates, followed by neurodegeneration and cognitive decline.3-7 These features of the disease are reflected by the ATN (amyloid, tau, neurodegeneration) classification system introduced by the National Institute on Aging and Alzheimer’s Association, aiming to classify Alzheimer’s disease on a biological basis.8 In this system, biomarkers of different modalities represent three different pathological processes in Alzheimer’s disease—Aβ plaques (A), phosphorylation of tau (T) and neurodegeneration (N). The gene discussed is MAPT; the disease is Alzheimer disease.