Methylenetetrahydrofolate reductase gene mutation and hyperhomocysteinemia as a risk factor for coronary heart disease in the Indian population.

ABSTRACT

OBJECTIVE: The screening and therapeutic guidelines for the management of lipid abnormalities are reasonably well established. However, other risk factors like hyperhomocysteinemia (HCA) and single nucleotide polymorphisms involving the angiotensin converting enzyme (ACE) and angiotensinogen genes, various clotting factors etc., have yet to be established firmly as other causative factors of atherothrombotic disease. Our study was aimed at finding the relationship between HCA, folate, vitamins B12 levels, and mutations in the 5,10-methylenetetrahydrofolate reductase (MTHFR) and cystathionine beta-synthase (CBS) genes. METHODS: We studied 230 subjects, which included patients with angiographically documented coronary heart disease (CHD) (n=115) and controls (n=115) with no history of CHD. RESULTS: Elevated levels of plasma homocysteine, above 18 nmoles/ml, were detected in 19.13% and 18.26% of our patients and controls, respectively. Homocysteine was significantly correlated to Apo A1 (r=0.51, p < 0.05) and Apo B (r=0.49, p < 0.05). The heterozygous MTHFR mutation was found to be 54.5% (12/22) in our patients with HCA. Of these, 31.8% (7/22) were deficient for plasma folate. Heterozygosity for T833C mutation in the CBS gene was observed in 9.99% (2/22) of our patients with HCA. Both these patients were also deficient for plasma folate and vitamin B12. CONCLUSION: In our study, heterozygosity for the thermolabile MTHFR mutation was found to be associated with hyperhomocysteinemia (HCA). This genetic predisposition to HCA could be risk factor for CHD and can be correlated with vitamin supplementation. To the best of our knowledge this is the first report from India on plasma homocysteine levels and its genetic aspect in patients with CHD.