Global KO of Trem2 reduced atherosclerosis in ApoE−/− mice;[40] CX3CR1‐CreER mediated myeloid selective Trem2 KO reduced atherosclerosis in Ldlr−/− mice;[41]Trem2 global KO or Trem2 KO bone marrow transplantation did not influence atherosclerotic plaque size but increased necrotic core of atherosclerotic lesion in Ldlr−/− mice;[42] TREM2 agonist antibody (AL002a) increased atherosclerotic plaque size and stability.[88] These conflicted results could be attributed to differences in KO strategies and disease models. The gene discussed is APOE; the disease is atherosclerosis.