Association between the IRF6 rs2235371 polymorphism and the risk of nonsyndromic cleft lip with or without cleft palate in Chinese Han populations: A meta-analysis.

OBJECTIVE: To investigate the association between the risk of nonsyndromic cleft lip with or without cleft palate (NSCL/P) and the IRF6 rs2235371 (C>T) polymorphism in Chinese Han populations.

DESIGN: PubMed, Web of Science and EMBASE were searched through May 31, 2016, to select eligible studies. Pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were applied to estimate the risk of NSCL/P associated with the IRF6 rs2235371 polymorphism. Subgroup analyses were conducted according to NSCL/P types (CLO, CPO and CLP) and the geographical location (Northern China and Southern China). Publication bias and sensitivity analyses were performed to assess the reliability of the results.

RESULTS: A total of 1275 NSCL/P cases and 1294 controls from seven eligible case-control studies were included. In the overall analysis, a significant association between the IRF6 rs2235371 polymorphism and the risk of NSCL/P was identified under all genetic models, with the exception of the recessive model (T vs. C: OR=0.68, 95%CI=0.60-0.76, P<0.00001). A subgroup analysis by NSCL/P types indicated that the variant T allele significantly decreased the risk of CLO and CLP but not CPO. A subgroup analysis of the geographical location further showed significantly decreased susceptibility in Northern China under all genetic models, but in Southern China, only the heterozygote and dominant models showed a significantly decreased risk of NSCL/P. Funnel plot analysis and the Egger linear regression method detected no publication bias.

CONCLUSIONS: The IRF6 rs2235371 T allele decreased the risk of NSCL/P in Chinese Han populations. However, further studies with large sample sizes should be conducted to confirm this association.