The C677T mutation in methylenetetrahydrofolate reductase gene, plasma homocysteine concentration and the risk of coronary artery disease

Background: The C677T mutation in methylenetetrahydrofolate reductase (MTHFR) gene is one of the causes of an elevated homocysteine plasma concentration and is probably one of the atherosclerotic risk factors.Aim: To assess the relationship between the presence of the MTHFR gene mutation, plasma homocysteine concentration and the risk of coronary artery disease (CAD).Methods: The study group consisted of 120 consecutive patients (78% were male, mean age 59.2±9.6 years) with angiographically confirmed CAD and 106 healthy volunteers (76% were male, mean age 47.4±6.0 years). The MTHFR gene mutation was detected based on the polymerase chain reaction and digestion with restrictive endonuclease HinfI. Total homocysteine plasma concentration was measured using HPLC. Folic acid and vitamin B12 plasma levels were assessed using the chemiluminescence method. Hyperhomocysteinemia was defined as homocysteine concentration ≥90 percentile of the control group which was ≥12.4 µmol/L.Results: The incidence of the mutation of allele T and the genotype TT was similar in patients and controls (51.7% vs 56.6%, and 9.2% vs 10.4%, NS, respectively). The folic acid and vitamin B12 levels were not related to the MTHFR genotype (folic acid: 8.1 ng/L in homozygotes TT vs 8.6 in heterozygotes CT and 8.3 in homozygotes CC; and vitamin B12: 273 pg/L vs 303.3 vs 314.3, respectively). Although homozygotes TT had significantly higher homocysteine concentration than heterozygotes and homozygotes CT or CC (15.4 vs 11.0 vs 11.2 µmol/L,