Lack of association of severe preeclampsia with maternal and fetal mutant alleles for tumor necrosis factor alpha and lymphotoxin alpha genes and plasma tumor necrosis factor alpha levels

OBJECTIVE: The purpose of this study was to determine whether the increased frequency of mutant alleles of the gene for tumor necrosis factor alpha and elevated maternal and fetal plasma levels of tumor necrosis factor alpha were associated with severe preeclampsia. STUDY DESIGN: We performed a prospective cross-sectional study involving 112 patients with severe preeclampsia matched for gestational age with 106 normotensive pregnant women. Deoxyribonucleic acid for restriction fragment length polymorphism analysis was extracted from maternal and fetal blood. Two mutations associated with the gene for tumor necrosis factor alpha were assayed by polymerase chain reaction. Polymerase chain reaction products were digested with the restriction enzyme Ncol and then fractionated by gel electrophoresis. Genotypic frequencies were calculated. Maternal and fetal plasma tumor necrosis factor alpha levels were assayed by the dual monoclonal antibody sandwich enzyme-linked immunosorbent assay technique. The chi2 test, the Fisher exact test, the Student t test, and the Mann-Whitney test were performed to calculate statistical significance. RESULTS: The differences in the genotypic frequencies of the two loci were not significant in either maternal or fetal samples between control women and women with pregnancies complicated by severe preeclampsia. There was no statistical difference in median maternal plasma levels of tumor necrosis factor alpha between control subjects (0.0 pg/mL) and patients with severe preeclampsia (2.5 pg/mL; P =.36). Unexpectedly, fetal plasma tumor necrosis factor alpha levels were found to be significantly elevated in control women (18.4 pg/mL) relative to women with severe preeclampsia (9.1 pg/mL; P <.0001). CONCLUSION: Neither the genotypic frequencies for tumor necrosis factor alpha mutant alleles nor maternal tumor necrosis factor alpha plasma levels were increased in patients with severe preeclampsia.