Stage 1 is characterized by asymptomatic cerebral amyloidosis that was documented either by a positive Amyloid PET or decreased CSF Aβ42 levels; stage 2 by amyloidosis plus neurodegeneration, documented either by hypometabolism at FDG-PET or by increased CSF tau levels or medial temporal lobe atrophy at MRI; stage 3 by evidence of amyloidosis, neurodegeneration, and subtle cognitive decline that does not meet yet the MCI criteria. The gene discussed is MAPT; the disease is amyloidosis.