Objective: To study the association of the A2756G polymorphism of the methionine synthase (MS) gene with nonsyndromic cleft lip with or without cleft palate (NSCL/P) in Chinese.
Methods: Ninety-seven NSCL/P case-parent triads were selected as the case group. One hundred and four healthy subjects and their biological parents were selected as control group. For all subjects the A2756G polymorphism of the MS gene was examined by PCR-RFLP method.
Results: There was no statistical difference in genotype and allele frequencies for MS A2756G variants among family members between case group and control group. The GG genotype was not detected in the offsprings and mothers. The odds ratio and confidence interval of genotype AG in offspring, father and mother were 1.78(0.74-4.34), 0.80(0.36-1.79) and 1.26(0.54-2.93) respectively. The odds ratio and confidence interval of allele G in offspring, father and mother were 1.70(0.78-3.73), 0.88(0.49-1.75), and 1.23(0.59-2.60) respectively. The G allele did not increase the risk of NSCL/P. Transmission disequilibrium test (TDT) analysis yielded no evidence of linkage disequilibrium (chi-square=0.034,P>0.05). The results of haplotype-based haplotype relative risk (HHRR) analysis (chi-square=0.03,P>0.05) and family-based association tests (FBAT) (Z=0.186, P>0.05) failed to show association between the MS A2756G variant and the risk of NSCL/P.
Conclusion: The A2756G polymorphism of the MS gene was not associated with NSCL/P in Chinese in the present study.