Objective: Non-homologous end joining (NHEJ) is one of the pathways of repair of DNA double-strand breaks. A number of genes involved in NHEJ have been implicated as breast cancer susceptibility genes such as LIG4. However, some studies have generated conflicting results. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis was to investigate association between LIG4 gene polymorphisms in the NHEJ pathway and breast cancer risk.
Methods: Studies focusing on the relationship between LIG4 gene polymorphisms and susceptibility to breast cancer were selected from the Pubmed, Cochrane library, Embase, Web of Science, Springerlink, CNKI and CBM databases. Data were extracted by two independent reviewers and the meta-analysis was performed with Review Manager Version 5.1.6 and STATA Version 12.0 software, calculating odds ratios (ORs) with 95% confidence intervals (95%CIs).
Results: According to the inclusion criteria, we final included seven studies with a total of 10,321 breast cancer cases and 10,160 healthy controls in the meta-analysis. The results showed no association between LIG4 gene polymorphisms (rs1805386 T>C, rs1805389 C>T, rs1805388 C>T and rs2232641 A>G) and breast cancer risk, suggesting that the mutant situation of these SNPs neither increased nor decreased the risk for breast cancer. In the subgroup analysis by Hardy-Weinberg equilibrium (HWE) and ethnicity, we also found no associations between the variants of LIG4 gene and breast cancer risk among HWE, non-HWE, Caucasians, Asians and Africans.
Conclusion: This meta-analysis suggests that there is a lack of any association between LIG4 gene polymorphisms and the risk of breast cancer.