MAPT and Alzheimer disease: The potential utility of cerebrospinal fluid (CSF) biomarkers in neurodegeneration has been shown by the development of β amyloid 1–42 (Aβ42), total tau protein (h-tau), and phosphorylated tau 181 (p-tau) assays; these are now well established as diagnostic biomarkers of AD and have entered routine clinical practice [3].