MAPT and early-onset autosomal dominant Alzheimer disease: In primary tauopathies, which include frontotemporal dementia, Pick’s disease, progressive supranuclear palsy, and corticobasal degeneration [2], tau is the main driver of the pathology, while in secondary tauopathies, such as Alzheimer’s disease, tauopathy occurs as a result of other proteinopathies.