MAPT and early-onset autosomal dominant Alzheimer disease: Formerly, the core criteria of AD diagnosis were based on clinical symptoms.1 In 2018, a research framework was put forward by the National Institute on Aging–Alzheimer’s Association in which every individual is classified based on specific biomarkers in the AT(N) classification.2 In this framework, the term “Alzheimer disease” refers to the presence of abnormal β-amyloid (Aβ) accumulation and neurofibrillary tau tangles measured by CSF Aβ or amyloid PET (that is, “A”), and “T,” measured by CSF phosphorylated tau (p-tau) or tau PET.