MAPT and Alzheimer disease: Currently, decreased Aß42 and Aß42/40 ratios along with increased phosphorylated tau-181 (p-tau181) in cerebrospinal fluid (CSF) have been standardized as the core fluid biomarkers of the ATN (amyloid-tau-neurodegeneration) scheme for the biological diagnosis of AD [1], allowing for its distinction from other dementia disorders with similar performance as amyloid PET [4,5,6,7].