MAPT and Alzheimer disease: The major biochemical biomarkers of AD pathology include: cerebrospinal fluid (CSF) 42 amino acid isoform of amyloid β (Aβ1–42) [4] and amyloid β 42/40 ratio (Aβ42/40) [5], which mirror the deposition of Aβ in brain tissue, and CSF total tau (t-tau) and hyperphosphorylated tau (p-tau), to assess neurofibrillary tangles and neuronal loss in the brain [6,7,8].