With the aid of complementary tests that demonstrated low concentration of β-amyloid peptide of 42aa in the CSF and positive amyloid PET (A), an increase in the concentration of hyperphosphorylated tau protein in the CSF and tau-PET(T), associated with neurodegeneration (N) the diagnosis of the pathophysiology of AD could be performed. The gene discussed is MAPT; the disease is Alzheimer disease.