Synergistic effect of renin-angiotensin system and nitric oxide synthase genes polymorphisms in pre-eclampsia.

BACKGROUND: Components of the renin-angiotensin system and endothelial nitric oxide synthase may co-operate in spiral artery remodelling during placentation, and thus reduce the uteroplacental resistance typical of normal pregnancy. Since lack of such remodelling and abnormal placentation are specific features of pre-eclampsia, it has been suggested that abnormal function of both components of the renin-angiotensin system and endothelial nitric oxide synthase may be involved in its pathogenesis. However, previous studies of the association between pre-eclampsia and polymorphisms of single genes encoding renin-angiotensin system components and endothelial nitric oxide synthase have yielded conflicting results. The aim of this study was to assess if interactions among different polymorphisms of the renin-angiotensin system and nitric oxide synthase are involved in the pathogenesis of pre-eclampsia. METHODS: Some 359 pregnant women were enrolled: 103 normotensive, 50 with chronic hypertension, 86 with gestational hypertension, and 120 with pre-eclampsia. DNA analysis was performed to evaluate angiotensin-converting enzyme I/D, angiotensin-II receptor 1 1166A/C, angiotensinogen M235T and endothelial constitutive nitric oxide synthase 4b/a polymorphisms. Odds ratios (OR) with 95% confidence interval (CI) and chi2 tests were calculated. RESULTS: The frequency of single gene polymorphisms was similar in each group. The frequency of pairs including the DD genotype of the angiotensin-converting enzyme I/D polymorphism plus other homozygous genotypes was significantly higher in pre-eclamptic patients than in controls (OR=3.04, 95% CI=1.16-7.93). CONCLUSIONS: Synergism of angiotensin-converting enzyme I/D and other polymorphisms of renin-angiotensin system components and nitric oxide synthase may be a risk factor for pre-eclampsia.

Factor V Leiden and factor II G20210A in preeclampsia and HELLP syndrome.

BACKGROUND: The association of factor V and factor II mutations with preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, and a possible role of the two thrombophilic mutations in the pathogenesis of the diseases have been previously investigated. The results, however, are still inconclusive and contradictory. METHODS: A case-control study was performed over an interval of 24 months, on 111 subjects with preeclampsia and 111 normal pregnant women matched for age and parity, without previous thromboembolic disorders. The subjects were tested for the mutation A1691G in the factor V gene (R506Q or Leiden mutation) and the mutation A20210G in the factor II (prothrombin) gene. The Student's t-test and the chi2-test were applied when appropriate, and odds ratios and 95% confidence intervals were calculated. RESULTS: Fourteen patients with preeclampsia (12.6%) had at least one of the two mutations, as compared with six controls (5.4%). Factor V Leiden was found in eight patients with preeclampsia (7.2%) and in five controls (4.5%). Factor II G20210A was detected in eight preeclamptic women (7.2%) and in one normal pregnant woman (0.9%)(p = 0.041). In the subgroup of 32 preeclamptic subjects with HELLP syndrome, factor V Leiden was found in three patients (9.3%) and factor II G20210A in two (6.2%). CONCLUSIONS: The prevalence of factor V and factor II mutations is increased in patients with preeclampsia; the thrombophilic mutations may interact with other pathogenic factors to determine the clinical features of the disease and of its complications.