The main polymorphisms of the APOE gene consist of alleles that translate the isoforms of the protein that differ only by a single amino acid substituted at positions 112 and 158: (i) ApoE-ε2 isoform (Cis112Cis158) is associated with the presentation of hyperlipoproteinemia type III; (ii) ApoE-ε4 isoform (Arg112Arg158) has been implicated in atherosclerosis [30,31], and at least one copy of this allele has been identified in 40–65% of patients with AD. This evidence concerns the gene APOE and Alzheimer disease.