APOE and Alzheimer disease: Extensive studies on biomarkers of AD in cerebrospinal fluid (CSF) have evidenced the presence of amyloid-β (Aβ) peptide [3,4], Tau as well as phosphorylated Tau (p-Tau) [5,6], and even a potential association with apolipoprotein E (APOE) ε4 allele [3,7].