Methylenetetrahydrofolate reductase gene polymorphisms in black South Africans and the association with preeclampsia

Background. A methylenetetrahydrofolate reductase (MTHFR) polymorphism (1317T --> C) that occurs commonly in black African individuals prompted this study to establish whether this polymorphism, alone or in association with other MTHFR variants, is associated with preeclampsia in black South African women. Methods. A group of 204 black women with preeclampsia was examined for the 677C --> T, 1298A --> C and 1317T --> C MTHFR polymorphic alleles using standard techniques. Also examined were women with early-onset preeclampsia (n = 67) and gestational hypertension (n = 78). Results were compared with 338 ethnically matched normotensive pregnant women who had normal full-term gestations. Results. No differences in the 677T --> C or 1298A --> C MTHFR alleles were found between the study groups and controls; very few women were homozygous for either variant allele. Significant differences were observed for the 1317T, C polymorphism: only 39% of preeclamptics were homozygous for the T allele compared with 52% of the control group [p = 0.002; 0.59 (0.42-0.83)]. Heterozygotes occurred significantly more frequently in preeclamptics (51%), compared with controls (41%) [P = 0.019; 1.49 (1.07-2.08)]. Allele frequencies also differed significantly between preeclamptics and controls [p = 0.003; 0.69 (0.53-0.88)]. Allele frequencies in women with gestational hypertension were statistically indistinguishable from those in controls. Conclusion. The low frequencies of the 677C --> T and 1298A --> C MTHFR variant alleles in black South Africans imply little or no role for these mutations in precclampsia in this population group. However, significant differences in the 1317T --> C allele in preeclamptics suggest that the MTHFR gene, or a closely associated: gene, may still have some role, as yet undefined, in the pathogenesis of preeclampsia.