Polymorphism of the Methionine Synthase Gene

Abstract
—Methionine synthase and 5,10-methylenetetrahydrofolate reductase (MTHFR) sequentially catalyze the remethylation of homocysteine to methionine. A point mutation in the encoding region of the methionine synthase gene, which results in substitution of an aspartic acid for a glycine residue (D919G), has been identified in patients of the cblG genetic complementation group; these patients exhibit significantly decreased methionine synthase activity. Nevertheless, the D919G mutation has also been reported to be common in the general population. In this study, we analyzed the distribution of methionine synthase D/G polymorphism in the Japanese population and examined the extent to which it is associated with altered homocysteine metabolism and late-onset vascular diseases. We studied 215 patients with coronary artery disease, 251 patients with histories of ischemic stroke, and 257 control subjects. The methionine synthase genotype was analyzed by polymerase chain reaction followed by HaeIII digestion; ...