Abstract: Objectives To investigate the relationship of methylenetetrahydrofolate reductase (MTHFR) and methioninesynthase reductase (MTRR) with unexplained recurrent spontaneous abortion (URSA). Methods Case control study was used to select 244 patients with URSA (miscarriage group) and 116 normal women (control group) who were admitted to Tianjin Medical University General Hospital and Tianjin Women’ s and Children’ s Health Center from January 2013 to March 2015. The oral mucosal epithelial cells were extracted using fluorescence quantitative PCR to detect MTHFR gene C677T, A1298C and MTRR gene loci of A66G single nucleotide polymorphisms (SNP). The relationship between folate metabolism related gene polymorphisms of MTHFR and MTRR and URSA was analysed. Results The frequency of C677T genotype MTHFR was significantly higher in URSA group than that in the control group, and the frequency of CT genotype was significantly lower than that of the control group (P<0.05). There was no significant difference in the frequencies of A1298C MTRR and A66G MTHFR between the two groups. The activity of MTHFR, red cell folate and plasma folate levels were significantly lower in URSA group than those of control group. Homocysteine levels were significantly higher in URSA group than those of control group (P<0.05). There were no significant differences in serum folic acid, red cell folate, homocysteine cysteine levels between patients <35 years old and ≥ 35 years old in URSA group. Conclusion C677T MTHFR gene polymorphism is associated with unexplained recurrent spontaneous abortion .

Key words: abortion, spontaneous, 5,10- methylenetetrahydrofolate reductase (FADH2), polymorphism, single nucleotide, unexplained recurrent spontaneous abortion, methionine synthase reductase