MTHFR C677T polymorphisms and childhood acute lymphoblastic leukemia: a meta-analysis.

To date, case-control studies on the association between methylenetetrahydrofolate reductase (MTHFR) C677T and childhood acute lymphoblastic leukemia have provided either controversial or inconclusive results. To clarify the effect of MTHFR C677T on the risk of childhood acute lymphoblastic leukemia, a meta-analysis of all case-control observational studies was performed. Heterogeneity (I(2)=65%, P<0.0001) for C677T among the studies was extreme. The random effects (RE) model showed that the 677T allele was not associated with a decreased susceptibility risk of childhood acute lymphoblastic leukemia compared with the C allele [OR=0.96, 95% confidence interval (CI) (0.88-1.04), P=0.34]. The contrast of homozygotes, recessive model and dominant model produced the same pattern of results as the allele contrast. Although MTHFR C677T was associated with increased risks of colorectal cancer, leukemia, and gastric cancer, our pooled data suggest no evidence for a major role of MTHFR C677T in the carcinogenesis of childhood acute lymphoblastic leukemia.