Relationship between unexplained recurrent pregnancy loss and 5,10-methylenetetrahydrofolate reductase) polymorphisms.

OBJECTIVE: To investigate the relationship between unexplained recurrent pregnancy loss (URPL) and polymorphisms of folate metabolism-related genes. DESIGN: A case-control study. SETTING: Urban university-based hospital. PATIENT(S): Two-hundred and eighteen women with URPL and 264 healthy controls. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Fluorescence quantitative polymerase chain reaction examination of sequences of the C677T and A1298C loci of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. RESULT(S): The frequency of the T allele at the MTHFR C677T locus in the URPL group was statistically significantly higher compared with the control group (odds ratio [OR] 1.324; 95% confidence interval [CI], 1.014-1.729), and the presence of the CC+CT genotype was statistically significantly reduced in the URPL group (OR 0.678; 95% CI, 0.471-0.974). The frequency of the C allele at the MTHFR A1298C locus in the URPL group was statistically significantly higher than that in the control group (OR 1.557; 95% CI, 1.066-2.275), and the presence of the CC+AC genotype was statistically significantly elevated in the URPL group (OR 1.740; 95% CI, 1.137-2.661). The frequency of MTHFR 677CT/1298AC compound genotypes in the URPL group was 6.589-fold higher compared with the control group. Most patients in the URPL group carried two mutant genes (69.3%), and the percentage of patients with two mutant genes was statistically significantly higher than in the control group (OR 4.996; 95% CI, 1.650-15.129). CONCLUSION(S): The MTHFR 1298AC genotype and composite heterozygote genotype (677CT/1298AC) are risk factors for URPL. The risk of URPL is highest in women carrying two mutations of A1298C and C677T locus in MTHFR.