TREM2 and Alzheimer disease: Known AD-associated genes localized to biologically coherent communities: APP, MAPT, and PSEN1/2 were linked to canonical amyloid and tau pathologies; APOE, CLU, and SORL1 to lipid metabolism and Aβ clearance; TREM2 and CD33 to microglial activation and immune response; and BIN1, PICALM, EPHA1, and GRN to intracellular trafficking and Proteostasis.