Original Article Association between Maternal MTHFR Polymorphisms and Nonsyndromic Cleft Lip with or without Cleft Palate in Offspring, A Meta-Analysis Based on 15 Case-Control Studies

Background: The methylenetetrahydrofolate reductase (MTHFR) is thought to be involved in the development of nonsyndromic cleft lip with or without cleft palate (NSCL/P). However, conflicting results have been obtained when evaluating the asso-ciation between maternal MTHFR C677T and A1298C polymorphisms and the risk of NSCL/P. In light of this gap, a meta-analysis of all eligible case-control studies was conducted in the present study. Materials and Methods: A total of 15 case-control studies were ultimately identified after a comprehensive literature search and Hardy-Weinberg equilibrium (HWE) exami-nation. Cochrane’s Q test and index of heterogeneity (I2) indicated no obvious heteroge-neity among studies. Results: Fixed or random-effects models were used to calculate the pooled odds ratios (ORs). The results showed that the TT genotype in mothers increased the likelihood of having NSCL/P offspring 1.25 times (95 % CI: 1.047-1.494) more than the CC homozygotes. Mean-while, maternal TT genotype increased the risk of producing NSCL/P offspring in recessiv