Apolipoprotein E gene (APOE) is the major risk gene identified as yet for late onset AD (LOAD), the commonest form of AD, which has an onset at more than 60 years of age [3, 4] The APOE protein serves as a ligand for low density lipoprotein receptor, and participates in the transport of cholesterol and other lipids among various cells [5]. This evidence concerns the gene APOE and Alzheimer disease.