The previously mentioned protective variant (rs72824905, p.Pro522Arg) identified in PLCG2, the gene encoding the enzyme phospholipase-C-γ2 that is highly expressed in microglia, was found to be associated with 1.5-fold reduced risk of AD in a three-stage case-control study of 83,133 subjects of European ancestry. The gene discussed is PLCG2; the disease is Alzheimer disease.