Objective: To investigate the association of the C677T polymorphism of the 5,10-methyleneterahydrofolate reductase(MTHFR) gene with preterm delivery(PTD) and low birth weight (LBW).
Methods: A total of 250 normal gestational age families and 250 PTD families were enrolled in the study. Polymerase Chain Reaction (PCR) followed by restriction enzyme digestion were used for genotyping the polymorphism of MTHFR C677T. A Maximum Likelihood Ratio Test approach based on the log-linear model was used to analyze the relationship of MTHFR gene polymorphism and risk of PTD and LBW.
Results: Firstly, we checked the Mendelian transmissions of the variant alleles of MTHFR 677T in PTD and LBW control-parent-triads using TDT test, respectively. These analyses of controls support Mendelian transmission. When children's genotypes were considered, the MTHFR CT and TT genotypes could significantly increase the risk of PTD and LBW, compared to the genotype of MTHFR CC, the odds ratio and 95% confidence interval (CI) for MTHFR CT and TT genotypes were 2.01,1.21-3.32 1.82, 1.02-3.26 in PTD group, and were 1.87, 1.08-3.24;1.90, 1.02-3.54 in LBW group respectively. When mother's genotypes were considered, the MTHFR gene polymorphism was not associated with PTD and LBW. Meanwhile, we also examined the association of mothers' and children's combined genotypes of MTHFR C677T with the risk of PTD and LBW, and did not find any significant interaction between mothers' and children's genotypes.
Conclusion: The infant MTHFR CT and TT genotypes are responsible for mothers' PTD and LBW in our study population. It supports that the non-Mendelian transmission among preterm children is due to a causal association between the MTHFR 677T variant alleles and preterm delivery and MTHFR gene likely affects LBW via shortened gestation (PTD).