Apolipoprotein E (APOE) has multiple functions in metabolism and immunoregulation. Its common germline variants APOE2, APOE3 and APOE4 give rise to three functionally distinct gene products. Previous studies reported yin-yang roles of APOE2 and APOE4 in immunological processes, but their effects in hematopoietic stem cell transplantation (HSCT) have never been studied. We performed APOE genotyping in two contemporary cohorts of 348 and 447 patients with acute myeloid leukemia (AML) who …