Advanced positron emission tomography (PET) brain imaging of hallmark amyloid and tau AD pathology using various radioactive tracers (e.g., 11C-Pittsburgh compound B, PiB [125], 18F-florbetapir [45], 18F-flutemetamol [80], 18F-florbetaben [173], 18F-TKH5105, and 18F-T807 [89]) provides disease specificity and facilitates ongoing research. The gene discussed is MAPT; the disease is Alzheimer disease.