In 2011, the National Institute on Aging and Alzheimer’s Association (NIA-AA) proposed separate diagnostic recommendations for the preclinical mild cognitive impairment and dementia stages of Alzheimer’s disease based on different biomarkers able to discriminate, in vivo, the different pathological entities, including beta-amyloid deposition, pathologic tau and neurodegeneration. The gene discussed is MAPT; the disease is Alzheimer disease.