Polymorphisms in human homeobox HLX1 and DNA repair RAD51 genes increase the risk of therapy-related acute myeloid leukemia

Studies of radiation-induced acute myelold leukemia (AML) in mice suggest that the number of target stem cells is a risk factor, and the HLX1 homeobox gene, which is important for hematopoietic development, is a candidate gene. The distribution of the C/T-3' untranslated region (UTR) polymorphism in HLX1 in patients with AML and therapy-related AML (t-AML) compared with controls was therefore determined. The presence of the variant HLX1 allele significantly increases the risk of t-AML (OR = 3.36, 95% Cl, 1.65-6.84). The DNA repair gene RAD51(135G/C-5'UTR) polymorphism also increases t-AML risk, and when combined analysis was performed on both RAD51 and HLX1 variant alleles, a synergistic 9.5-fold increase (95% Cl, 2.22-40.64) in the risk of t-AML was observed. We suggest that the HLX1 polymorphism has an effect on stem cell numbers, whereas an increased DNA repair capacity (RAD51) will suppress apoptosis, a genetic interaction that may increase the number of genomes at risk during cancer therapy.