Abstract: AIM: To study the polymorphism distribution of methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) genes and their influence on serum homocysteine (Hcy) concentration.  METHODS: A total of 148 patients diagnosed with ischemic stroke from November 2020 to February 2021 in Yijishan Hospital of Wanan Medical College were selected for the study, and patients were typed for MTHFR 677C/T and MTRR 66A/G genes using fluorescent staining in situ hybridization technique. Serum Hcy concentrations were measured in 21 patients using a circulating enzyme assay. The distribution of MTHFR 677C/T and MTRR 66A/G gene polymorphisms were analyzed, and the differences in serum Hcy concentrations between patients with different genotypes were compared. RESULTS: The mutation rates of MTHFR 677C/T and MTRR 66A/G genes were 42.57% and 26.01%, respectively, and no significant differences in gene distribution frequencies were observed between men and women (P>0.05). The mean Hcy serum concentration was (16.04±4.34) μmol/L in 21 patients, including 8 patients (38.10%) with <15 μmol/L and 13 patients (61.90%) with ≥15 μmol/L. The Hcy serum concentrations in patients with different genotypes of MTHFR were TT (18.91±5.34) μmol/L, CT (14.38±1.84) μmol/L and CC (13.58±2.86) μmol/L, respectively, and were statistically different (P<0.001). Serum Hcy concentrations in patients with different genotypes of MTRR were not statistically different (P>0.05). CONCLUSION: MTHFR gene polymorphisms can affect serum Hcy concentrations. The MTHFR genotyping can be considered for individualized folic acid supplement. This conclusion should be further verified by expanding the clinical sample size.

Key words: methylenetetrahydrofolate reductase, methionine synthase reductase, gene polymorphism, homocysteine, folic acid, individualized dosing