TREM2 and Alzheimer disease: Rare variant (rs616338, p.Ser209Phe, p = 4.56 × 10−10, OR = 1.43, MAFcases = 0.011, MAFcontrols = 0.008) in ABI3 was previously reported, and ABI3 is specifically expressed in microglia (S2 Fig, similar expression pattern in human compared to other AD genes implicated by human genetics including TREM2, HLA-DRB1, PLCG2, SORL1, SCIMP, and MS4A6A) and thought to play a role in microglia-mediated innate immunity in AD [69].