Core AD biomarkers include: (1) cerebrospinal fluid (CSF) low levels of Aβ42 or the Aβ42/40 ratio and brain amyloid deposition evidenced by PET imaging; (2) increased total tau (t-Tau) and phosphorylated tau (p-Tau) representing cortical neuronal loss and cortical tangle formation, respectively; and (3) hippocampal atrophy shown on MRI [34]. The gene discussed is MAPT; the disease is Alzheimer disease.