AD biomarkers, including cerebrospinal fluid (CSF) [6] or positron emission tomography (PET) [7, 8] measures of amyloid and tau proteins, correlate well with postmortem amyloid and tau (A/T) pathology, but their levels have not been shown to accurately track disease progression [9, 10] to provide information on neurodegeneration. The gene discussed is MAPT; the disease is Alzheimer disease.