Genetic polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR C677T and A1298C) in healthy Korean

Genetic mutation in the MTHFR gene (C677T and A1298C) have been shown to result in reduced MTHFR activity. Elevated plasma homocysteine levels can result from defective remethylation of methylenetetrahydrofolate reductase (MTHFR). Hyperhomocysteinemia has recently been known to be an important risk factor for cerebrovascular disease. We have studied the genotype frequencies of MTHFR (C677T and A1298C) gene in 254 healthy Korean subjects without vascular diseases and cancers, aged 20 to 90 years. The frequency of subjects homozygous for the 677TT genotype was 13.4%, and that of those homozygous for the 1298CC genotype was 2.0%. The frequency of individuals heterozygous for both mutations (677CT/1298AC genotype) was 11.9%. The highest and lowest frequency of combined MTHFR genotype was 677CT/1298AA (39.1%) and 677CC/1298CC (1.6%), respectively. Moreover, no individuals had the three combined genotypes such as 677CT/1298CC, 677TT/1298AC and 677TT/1298CC. The frequency of MTHFR 677T allele in Korean was 0.39, which is similar to Japanese (0.41), Chinese (0.40 and 0.41), higher than Caucasian (0.27-0.37). The frequency of MTHFR 1298C allele in Korean was 0.12, which is the lowest among the populations such as Japanese (0.19), Chinese (0.17 and 0.19) and Caucasian (0.29-0.36). And the frequency of combined normal genotype (677CC/1298AA) in Korean was 24.5%, which is higher than Japanese (15.2%), Chinese (16.4% and 18.7%) and Caucacian (10.8-18.4%), but lower than that of South African (36.8%). The MTHFR C677T and A1298C mutation data should be useful for studying the differences of world populations, and significance of the vascular diseases as well as thrombotic diseases.