Relationship between folate level of red cell and MTHFR polymorphisms with unexplained recurrent spontaneous abortion

Objective To explore the relationship between folate level of red cell and methylene tetrahydrofolate reductase(MTHFR) gene mutation in women with unexplained recurrent spontaneous abortion (URSA) and whether MTHFR and the level of red cell folate are the risk factors for URSA. Methods Ninety-three women in early pregnancy were selected and divided into two groups:36 in the URSA group and 57 in the control group who had at least one live birth without history of spontaneous abortion. The level of red cell folate were detected by time-resolved fluorescence measurement. MTHFR C677T gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results The folate level in red cell and MTHFR TT genotype were independently related to URSA. The frequency of the MTHFR TT genotype in URSA group was 55.6%(20/36), which was significantly higher than that in the control[31.6%(18/57),P=0.022, OR=2.7,95%CI 1.1-6.4]. The frequency of T allele in URSA group was significantly higher than that of the control (75.0% vs 55.0%, P=0. 022). The mean level of folate in URSA group was significantly lower than that in control group [(538.49±232.65) nmol/L vs (679.25±244.95) nmol/L,P=0. 008]. The same was found within the same genotypes between the two groups. The risk of URSA showed no difference between different genotypes when the folate level was ≥430.35 nmol/L. When the folate level was 430.35 nmol/L, the frequency of TT genotype was 66.7%(10/15) and 27.3%(3/11) in the RSA and control group, respectively. And the risk of URSA was 2.7 to 5.33 times as the other genotypes (95% CI 1.0207-10.057). Conclusions Both MTHFR C677T gene polymorphism and red cell folate level play a role in the genesis of URSA. The reduced level of red cell folate combined with TT genotype might remarkably increase the risk of URSA.