Myocardial Infarction in Young Women in Relation to Plasma Total Homocysteine, Folate, and a Common Variant in the Methylenetetrahydrofolate Reductase Gene

Background In a population-based study, we examined the relationship between the risk of myocardial infarction (MI) among young women and plasma total homocysteine (tHCY), folate, vitamin B12, and a common cytosine (C) to thymine (T) polymorphism in the gene for 5,10-methylenetetrahydrofolate reductase (MTHFR). Methods and Results In-person interviews and nonfasting blood samples were obtained from 79 women =]15.6 {micro}mol/L were at approximately twice the risk of MI as women with tHCY =]8.39 nmol/L had an {approx}50% lower risk of MI than women with folate <5.27 nmol/L (OR, 0.54; 95% CI, 0.23 to 1.28). There was no association with vitamin B12 concentration. Among control subjects, 12.7% were homozygous for the MTHFR T677 allele, and these women had higher plasma tHCY and lower plasma folate than women with other genotypes. Ten percent of case patients were homozygous for te T677 allele, and there was no association of homozygosity for T677 with MI risk (OR, 0.90; 95% CI, 0.31 to 2.29). Conclusions These data support the hypothesis that elevated plasma tHCY and low plasma folate are risk factors for MI among young women. Although homozygosity for MTHFR T677 is related to increased plasma tHCY and low plasma folate, this genetic characteristic is not a risk factor for MI in this population.