Folate metabolic gene polymorphisms and childhood acute lymphoblastic leukemia: a case-control study

We genotyped six folate metabolic pathway genes for 11 polymorphisms in 460 cases of childhood acute lymphoblastic leukemia (ALL) and 552 ethnically matched controls. None of the polymorphisms except the 66A>G (I22M) in the 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) gene showed any effect on disease risk. The carriers of the G-allele were associated with a marginal decreased risk of ALL (gender-adjusted global P=0.03; multiple-testing corrected P=0.25). Analysis of four polymorphisms in the MTRR gene showed statistically significant differences in haplotype distribution between cases and controls (global P<0.0001). The haplotypes GCAC (odds ratio (OR) 0.5, 95% confidence interval (CI) 0.4-0.6) and ATAC (OR 0.5, 95% CI 0.3-0.6) were associated with a reduced risk and the haplotypes ACAC (OR 2.3, 95% CI 1.8-2.9) and GTAC (OR 1.8, 95% CI 1.4-2.3) with an increased risk. The genotype-combination analyses indicated that the best model stratifies cases and controls based on the 66A>G and the 524C>T polymorphisms in the MTRR gene (global P=0.03). Our results suggest that, besides a weak association of childhood ALL with the 66A>G polymorphism, haplotypes within the MTRR gene may, in part, account for population-based differences in risk.