There is a strong correlation between tau pathological burden in the brain and cognitive decline in AD [4–6], a finding bolstered by recent tau positron emission tomography imaging studies in AD [7, 8] and FTLD due to tau pathology [9, 10], suggesting that it is the development of abundant tau inclusions that ultimately leads to the neurodegeneration observed in AD and the other tauopathies. The gene discussed is MAPT; the disease is Alzheimer disease.