Because atypical AD variants are relatively rare,45,46 we conducted a large-scale multicentre study on atypical AD, using patient-specific tau-PET across 14 sites worldwide (n = 320, with n = 68 typical AD cases serving as the benchmark group) and resting-state functional MRI (fMRI) data from healthy elderly controls in the Alzheimer's Disease Neuroimaging Initiative [ADNI, n = 42 cognitively normal (CN) Aβ-negative individuals], as well as post-mortem datasets from two sites [University of Pennsylvania (UPENN) n = 63, University of California, San Francisco (UCSF) n = 30]. This evidence concerns the gene MAPT and Alzheimer disease.