TREM2 is a modulator of lipid metabolism, and the R47H variant of TREM2 has reduced affinity for apolipoproteins (e.g., apolipoprotein E; APOE) or lipid ligands, which may contribute to the increased late‐onset AD risk associated with this TREM2 variant [24, 35]. Here, APOE is linked to Alzheimer disease.