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Background and ObjectivesWe examined common polymorphisms in the genes for glutathione S-transferase (GST), cytochrome P450 (CYP), quinone oxoreductase (NQO1), methylene tetrahydrofolate reductase (MTHFR), and thymidylate synthetase (TYMS) and the role of gender associated with the susceptibility to de novo acute leukemia (AL). Design and MethodsWe conducted a case-control study analyzing the prevalence of the polymorphisms CYP1A1*2A, CYP2E1*5B, CYP3A4*1B, del{GSTT1}, del{GSTM1}, NQO1*2, MTHFR C6777, and TYMS 2R/3R in 443 patients with AL [302 with acute myeloblastic leukemia (AML) and 141 with acute lymphoblastic leukemia (ALL)] and 454 control volunteers, using polymerase chain reaction (PCR)-based methods. ResultsWe found a higher incidence of del{GSTT1} in patients with AML than among controls (25.6% vs. 13.7%, OR=2.2, p<0.001) and a higher incidence of NQO1*2 homozygosity (NQO1*2hom.) in males with the M3 FAB subtype than in control males (8.6% vs. 2.2%, OR=4.9, p=0.02). The del{GSTT1} and NQO1*2hom. polymorphisms increased the risk of ALL (OR=2.2 and 3.0, p=0.001 and 0.003, respectively). The higher risk conferred by NQO1*2hom. and del{GSTT1} mainly affected males (OR=6.1 and 2.4; p=0.002 and 0.005, respectively). Interpretation and ConclusionsMales harboring NQO1*2hom. and del{GSTT1} polymorphisms showed a higher risk than females of developing AL. Thus, gender might influence the risk of AL associated with these genetic polymorphisms. On the whole AL is more common in males of all age groups, 4 a fact that remains unexplained. Although the clinical and biological aspects of leukemia are well documented, little is known about the factors that condition an individual's susceptibility to de novo leukemia. Normal polymorphic variations in several genes, together with dietary effects, environmental exposure to carcinogens, and individual immune system characteristics are likely to be factors that predispose individuals to develop AL.5 Polymorphisms could also explain the different incidence of AL observed between the genders.Genetic polymorphisms in the drug-metabolizing enzymes are extremely common and may contribute to the risk of developing cancers. These polymorphisms could explain differences in the way in which individuals metabolize chemical agents.6 Studies have included polymorphisms of genes coding for P450 cytochromes (CYP), which are involved in phase I of metabolism (oxidation/activation). Most polymorphisms described for these genes, such as T6235C of CYP1A1 (CYP1A1*2A), C-1019T of CYP2E1 (CYP2E1*5B), and -A290G of CYP3A4 (CYP3A4*1B), are believed to cause an increase in enzymatic activity. They have been implicated in the bioactivation of several chemical carcinogens and the conversion of polyaromatic hydrocarbons from tobacco smoke into intermediate reactive metabolites, some of which can damage DNA.7 Glutathione Smethyl transferases (GST) are implicated in phase II of metabolism (conjugation/detoxification). Two widespread genetic polymorphisms that involve deletions in the GSTT1 and GSTM1 ge...

Patients with essential thrombocythemia (ET) and polycythemia vera (PV) have an increased incidence of acute myeloid leukemia and new nonhematologic malignancies compared with the general population. However, information on the factors determining the risk for such complications is limited. In the present study, we investigated whether constitutional genetic variations in DNA repair predispose to leukemic transformation and new nonmyeloid neoplasias in patients with ET and PV. Case-control studies for predispo-

The JAK2V617F allele burden has been identified as a risk factor for vascular events and myelofibrotic transformation in polycythemia vera (PV) and essential thrombocythemia (ET). However, all previous studies have evaluated a single time point JAK2V617F measurement. Therefore, the frequency and the clinical significance of changes in the JAK2V617F mutant load occurring during the disease evolution remain unknown. In the present study, JAK2V617F monitoring was performed during the follow‐up of 347 patients (PV = 163, ET = 184). According to their JAK2V617F evolutionary patterns, patients were stratified as stable < 50% (n = 261), stable ≥50% (n = 52), progressive increase (n = 24) and unexplained decrease (n = 10). After a 2,453 person‐years follow‐up, a total of 59 thrombotic events, 16 major hemorrhages, and 27 cases of myelofibrotic transformations were registered. At multivariate analyses, patients with a persistently high (≥50%) or unsteady JAK2V617F load during follow‐up had an increased risk of myelofibrotic transformation (Incidence rate ratio [IRR]: 20.7, 95% CI: 6.5–65.4; P < 0.001) and a trend for a higher incidence of thrombosis (IRR: 1.7, 1–3.3; P = 0.05) than patients with a stable allele burden below 50%. In conclusion, JAK2V617F monitoring could be useful in patients with PV and ET for predicting disease's complications, especially myelofibrotic transformation. Am. J. Hematol. 89:517–523, 2014. © 2014 Wiley Periodicals, Inc.