Objective: To investigate the association between concentrations of plasma homocysteine and folic acid, 5,10-methylenetetrahydrofolate reductase (MTHFR) C667T mutation and venous thromboembolism (VTE) and to analyze the effect of MTHFR C667T mutation on concentrations of plasma homocysteine and folic acid.
Methods: In 58 patients with VTE and 58 sex and age matched controls, epidemiological risk factors were surveyed. The concentration of plasma homocysteine was measured by high performance liquid chromatography, and the concentration of plasma folic acid was measured by radioimmunoassay. MTHFR C667T genotype was measured by PCR-RFLP.
Results: The concentrations of plasma homocysteine and folic acid showed significant difference between the case group and the control group (OR = 1.5, 95% CI: 1.216 - 2.213 and OR = 0.396, 95% CI: 0.149 - 0.709, respectively). There was no significant difference in the frequency of mutant alleles in site 667 of MTHFR gene between the cases and the controls (P > 0.05). The concentration of plasma folic acid was associated with the concentration of plasma homocysteine (multiple correlation coefficient = -2.061, P < 0.05). The MTHFR C667T polymorphism was associated with the concentration of plasma folic acid but not with the concentration of plasma homocysteine in both the case group and the control group. The multiple correlation coefficient between the MTHFR C667T polymorphism and the concentration of plasma folic acid is 0.5856 (P < 0.01).
Conclusions: The results of our study demonstrate that hyperhomocysteinemia and folic acid deficiency are independent risk factors for VTE. Folic acid deficiency is a cause of hyperhomocystinemia while the MTHFR C667T mutation is one of the possible genetic factors causing folic acid deficiency in this Chinese population.