Well-established fluid biomarkers for AD include CSF, plasma, and molecular markers, with CSF Aβ40, Aβ42, Aβ42/Aβ40 ratio, phosphorylated Tau 181 and total Tau (pTau181 and tTau, respectively) being the most used worldwide [17,18,19,20,21,22] (Figure 1). This evidence concerns the gene MAPT and Alzheimer disease.