LOAD heritability varies from 58% to 79% [4] and, despite the tremendous progress in AD genetics in the last twenty years, the total proportion of phenotypic variance explained by all the combined variants (including APOE genotype and genome wide association studies [GWAS] signals) is estimated to be 23% [5], which suggests a large proportion of the heritability of AD still remains unexplained. This evidence concerns the gene APOE and Alzheimer disease.