Lower levels of CSF Aβ42, higher CSF total tau (T-Tau), and higher tau phosphorylated at threonine 181 (P-Tau181), as well as biomarker ratios (T-Tau/Aβ42 or P-Tau/Aβ42) distinguish patients from controls [1], [2], [3], [4], [5] and predict conversion from mild cognitive impairment (MCI) to AD [1], [2], [6], [7], [8], [9]. The gene discussed is MAPT; the disease is Alzheimer disease.