MAPT and Alzheimer disease: Levels of total tau (T-tau) and tau phosphorylated at threonine 181 (P-tau) are elevated in CSF of AD [T-tau: 559 (85-2782) ng/L, P-tau: 82 (17-279) ng/L] and MCI due to AD [T-tau: 582 (83-2174) ng/L, P-tau: 81 (15-183) ng/L] compared to age-matched controls [T-tau: 280 (42-915) ng/L, P-tau: 51 (16-156) ng/L] [19].