The central nervous system (CNS) is rich in lipoprotein components, particularly apolipoprotein-E (ApoE)-rich high-density lipoprotein (HDL) (Vance and Hayashi, 2010), and the ApoE polymorphism has been stablished as a major risk factor for AD (Corder et al., 1993). The gene discussed is APOE; the disease is Alzheimer disease.