In order to support the diagnosis of AD, the total tau protein (t-tau), phosphorylated tau (p-tau), β-amyloid proteins Aβ1–42 (Aβ)/Aβ1–40 and the ratio Aβ1–42/Aβ1–40 are the markers that are quantified routinely in CSF, but they are not sensitive and specific enough to be used exclusively; this is why they are used in combination with imaging techniques [19,35]. This evidence concerns the gene MAPT and Alzheimer disease.