We analyzed sarkosyl-insoluble pathological tau proteins prepared from brains of patients with Alzheimer’s disease, Pick’s disease, progressive supranuclear palsy, corticobasal degeneration, globular glial tauopathy, and frontotemporal dementia and parkinsonisms linked to chromosome 17 with tau inclusions using liquid chromatography mass spectrometry. The gene discussed is MAPT; the disease is Pick disease.