Accordingly, genome-wide association studies over the past decade have identified more than 70 genetic loci associated with late-onset AD, many involving genes selectively or predominantly expressed in microglia, such as TREM2, APOE, CD33, INPP5D, ABI3, and members of the MS4A gene clusters (Bellenguez et al., 2022, Kunkle et al., 2019, Lambert et al., 2013, Wightman et al., 2021). Here, TREM2 is linked to Alzheimer disease.