Association between BHMT gene rs3733890 polymorphism and cancer risk: evidence from a meta-analysis

Background and objective: The gene betaine-homocysteine methyltransferase (BHMT) has drawn much attention during the past decades. An increasing number of clinical and genetic investigations have supposed that BHMT rs3733890 polymorphism might be associated with risk of breast cancer and ovarian cancer. As no consistent conclusion has been achieved, we conducted an up-to-date summary of BHMT rs3733890 polymorphism and cancer risk through a meta-analysis. Materials and methods: The articles were collected from PubMed, Google Scholar, and CNKI (Chinese) databases up to December 2015. Then, the correlations were determined by reading the titles and abstracts and by further reading the full text to filter the unqualified articles. Odds ratio (OR) and the corresponding 95% confidence intervals (CI) were used to assess the results. Results: Among 187 articles collected in the analysis, seven studies with a total of 2,832 cases and 3,958 controls were included for evaluation of the association between BHMT rs3733890 polymorphism and susceptibility of cancer risk. The heterogeneity test showed no significant differences. Furthermore, we found that BHMT -742G>A polymorphism in case and control groups showed no statistically significant association with susceptibility in various cancer types except for uterine cervical cancer (A vs G: OR =0.641, 95% CI =0.445-0.923, P=0.017; AA+AG vs GG: OR =0.579, 95% CI =0.362-0.924, P=0.022). In addition, no statistically significant association was uncovered when stratification analyses were conducted by ethnicity and genotyping methods. Conclusion: Our results have shown no obvious evidence that rs3733890 polymorphism in BHMT gene affected the susceptibility of head and neck squamous cell carcinoma, breast cancer, ovarian cancer, colorectal adenoma, and liver cancer. In contrast, we found the protective role of BHMT -742G>A polymorphism in uterine cervical cancer incidence. Future well-designed studies comprising larger sample size are warranted to verify our findings.