Methylenetetrahydrofolate reductase 677 C → T polymorphism, plasma folate, vitamin B12 concentrations, and risk of preeclampsia among black African women from Zimbabwe

We conducted a case control study at Harare Maternity Hospital, Zimbabwe. We genotyped a total of 171 cases with preeclampsia or eclampsia and 185 normotensive control subjects for the methylenetetrahydrofolate reductase (MTHFR) 677 C → T genotype. The wild-type allele frequency among cases and controls was 91.2 and 91.3%, respectively. Only one subject (0.3%) was homozygous for the 677 C → T MTHFR genotype and this subject had preeclampsia. After adjustment for confounding factors, there was statistically no significant association between maternal MTHFR genotype and risk of preeclampsia (adjusted odds ratio = 1.0; 95% CI, 0.5-1.9). In addition, plasma homocyst(e)ine, vitamin B12, and folate concentrations were not statistically different between normotensive control subjects with wild-type genotype as compared with normotensive subjects who were heterozygous for the mutant allele. Conversely, there was a strong graded association between maternal plasma folate concentration and risk of preeclampsia. Women with plasma folate concentrations less than 5.7 nmol/L experienced a 10.4-fold increase in risk of preeclampsia. There was no clear pattern of preeclampsia risk and vitamin B12 concentrations. (C) 2000 Academic Press.