Genome-wide association studies (GWAS) for AD have identified multiple single nucleotide polymorphisms (SNPs) in genes associated with AD risk, a large subset of which are primarily expressed in microglia: INPP5D, TREM2, CD33, PLCG2, CASS4, HLA-DRB5-DRB1, LILRB2, MS4A4A, ABI3, SCIMP, and PTK2B [2,3,4,5,6] and reviewed in [7] and [8]. The gene discussed is TREM2; the disease is Alzheimer disease.