In this study, we investigated further whether these is an association between 34 donor SNPs in the four co-stimulatory genes (TNFSF4, CTLA4, CD28, and PDCD1) and the occurrence of adverse outcomes (mortality, relapse, CMV infection, and GVHD) for patients with AML and ALL. The gene discussed is CTLA4; the disease is acute myeloid leukemia.