A common polymorphism in the apolipoprotein E gene (ApoE), located on chromosome 19, has been established as the most common genetic risk factor for AD in Caucasian ethnic groups, including the Russian population (Saunders et al., 1993; Schmechel et al., 1993; Farrer et al., 1997; Rogaev, 1999). This evidence concerns the gene APOE and Alzheimer disease.