For AD, GWAS have identified dozens of risk loci, including genes involved in microglial function, immune response, and protein catabolism, such as apolipoprotein E (APOE), clusterin (CLU), phosphatidylinositol binding clathrin assembly protein (PICALM), complement receptor 1 (CR1), bridging integrator 1 (BR1), adenosine tri-phosphate binding cassette subfamily A member 7 (ABCA7), membrane spanning 4-domains A (MS4A), cluster of differentiation 2 associated protein (CD2AP), and ephrin type-A receptor 1 (EPHA1) [21,22,23]. The gene discussed is APOE; the disease is Alzheimer disease.