Inherited thrombophilias and adverse pregnancy outcomes: a case-control study in an Australian population

The "Bad Father": Paternal Role in Biology of Pregnancy and in Birth Outcome

Pregnancy is generally studied as a biological interaction between a mother and a fetus; however, the father, with his characteristics, lifestyle, genetics, and living environment, is by no means unrelated to the outcome of pregnancy. The half of the fetal genetic heritage of paternal derivation can be decisive in cases of inherited chromosomal disorders, and can be the result of de novo genetic alterations. In addition to the strictly pathological aspects, paternal genetics may transmit thrombophilic traits that affect the implantation and vascular construction of the feto-placental unit, lead to placenta-mediated diseases such as pre-eclampsia and fetal growth retardation, and contribute to the multifactorial genesis of preterm delivery. Biological aspects of immunological tolerance to paternal antigens also appear to be crucial for these pathologies. Finally, this review describes the biological findings by which the environment, exposure to pathogens, lifestyle, and nutritional style of the father affect fetal pathophysiological and epigenetic definition.

Pathophysiological, immunogenetic, anatomopathological profile of thrombophilia in pregnancy

Thrombophilic states have been associated with early and/or late pregnancy loss and possibly other severe obstetrical complications. Pregnancy-induced hypercoagulability, increased stasis, and the consequences of inherited and acquired thrombophilia are just a few of the factors that contribute to the development of thrombosis in pregnancy. In this review, we illustrate the impact that these factors have on the development of thrombophilia during pregnancy. We also explore how thrombophilia impact pregnancy outcomes. Next, we discuss how human leukocyte antigen G plays a part in thrombophilia during pregnancy by regulating cytokine release to prevent trophoblastic cell invasion and maintain local immunotolerance constant. Human leukocyte antigen class E is briefly explored with thrombophilia in pregnancy. Regarding the anatomopathologic aspect, we describe the different histopathological lesions of the placenta found in women with thrombophilia.

Thrombomodulin and pregnancy in the limelight: Insights into the therapeutic aspect of thrombomodulin in pregnancy complications

BACKGROUND

Thrombomodulin (TM) is a transmembrane glycoprotein expressed on the endothelial cell functioning as a cofactor in the anticoagulation system. However, aside from anticoagulation, recent studies have revealed its multiple organ protective roles such as anti-inflammation, angiogenesis, and cell proliferation, which may redefine the function of TM. Although TM is predominantly expressed on placental trophoblasts, the physiological role of TM during pregnancy remains unclear. Because the understanding of TM function has drastically progressed, these new discoveries shed light on the unknown activities of placental TM. Moreover, the clinical application of recombinant TM (rTM) has opened the possibility of TM as a therapeutic target for pregnancy complications.

OBJECTIVES

Here, we comprehensively review the studies elucidating the role of TM during pregnancy from both classic and newly discovered perspectives, and seek for its potential as a therapeutic target for pregnancy complications.

METHODS

Basic research using trophoblast cells and transgenic mice, as well as cohort studies of inherited TM deficiency and clinical trials of rTM were summarized, which led us to further discuss the clinical application of rTM as a novel therapeutic for pregnancy complications.

RESULTS AND CONCLUSION

Accumulating evidence suggest the relevance of placental TM deficiency in pregnancy complications such as miscarriage, fetal growth restriction, and preeclampsia. Most importantly, promising results in animal studies and clinical trials further assure the possibility of rTM as an optimal therapeutic for such conditions. The therapeutic potential of TM raised throughout this review could drastically change the clinical approach to pregnancy complication and improve maternal outcomes.

Maternal inherited thrombophilia and pregnancy outcomes

Thrombophilia is a group of genetical disorders that cause blood to clot abnormally. Thrombophilia is linked to recurrent pregnancy loss, foetal growth restriction, late miscarriages, stillbirth and preeclampsia. Clinicians usually apply the term thrombophilia only to patients with atypical thrombosis. A successful outcome of pregnancy requires an efficient uteroplacental circulation. Since this system may be compromised by disorders associated with a prothrombotic state, it was postulated that maternal thrombophilia might be a risk factor for preeclampsia and intrauterine growth retardation. The study included 459 pregnant women with gestational ages ranging from 14 weeks to 28 weeks and the patients in the study were tested for hereditary thrombophilia. The type of thrombophilic mutation most common found was the MTHFR mutation (25.7%), followed by the prothrombin gene mutation (20.9%) and the Leiden factor V mutation (15.7%). Also 15.03% patients had been diagnosed with preeclampsia and 6.75% of the pregnant women had IUGR fetuses.

Cardiovascular risk after hypertensive disorders of pregnancy in women with and without inheritable Thrombophilia

Aim of this study was to compare cardiovascular risk in women with and without inheritable thrombophilia after hypertensive disorders of pregnancy (HDP). Blood pressure, anthropometrics and blood samples were measured 9-13 years after early-onset (<34 weeks) HDP. Amongst the 114 women included, no differences in hypertension (31.1% vs. 33.7%, OR 0.90 95% CI (0.29-2.79)), body mass index > 25 kg/m² (43.8% vs. 53.1%, OR 0.69 95% CI (0.24-2.00)) or metabolic syndrome (18.8% vs. 13.3%, OR 1.51 95% CI (0.38-6.02)) were found. These data show similar cardiovascular risk profile in women with and without inheritable thrombophilia.

Therapeutic Implications of Inherited Thrombophilia in Pregnancy

BACKGROUND

Inherited (hereditary) thrombophilia is a genetic disorder that affects coagulation, being responsible for more than 60% of idiopathic (spontaneous or unprovoked) thromboembolic events. Association of inherited thrombophilia with pregnancy increases the risk of thromboembolic disease, and it may be related to many complications, such as preeclampsia, recurrent miscarriage intrauterine growth restriction, early detachment of placenta, and prematurity.

AREAS OF UNCERTAINTY

Interpretation of a positive test for thrombophilia in pregnant women is difficult because they have many natural changes in the coagulation system. Genetic diagnosis of thrombophilia, after a thrombotic event or during a pregnancy complication, has a major importance, not only to define its etiology but also to determine the duration of anticoagulant treatment and risk stratification for prophylaxis treatment.

DATA SOURCES

Literature search was performed using electronic database (PubMed) between April 1981 and November 2018. We used different keywords and MeSH terms to generate the most relevant results related to the inherited thrombophilia and its impact on pregnancy.

RESULTS

Screening for inherited thrombophilia in young women is recommended in case of personal history of venous thromboembolism, first-degree relatives with a history of high-risk thrombophilia, or personal history of second-trimester miscarriage. Decision to recommend thromboprophylaxis with anticoagulant treatment in pregnant women with inherited thrombophilia is determined by history of venous thromboembolism, type and associated risk of inherited thrombophilia, and presence of additional risk factors. Low-molecular-weight heparins are the preferred agents for prophylaxis in pregnancy, while the doses vary depending on thrombophilia type, personal history, and associated risk factors.

CONCLUSIONS

Association between 2 procoagulant conditions, inherited thrombophilia and pregnancy, has an important impact for the mother and fetus. This review will summarize the impact of each inherited prothrombotic factor on cardiovascular and pregnancy outcomes and will discuss the role of anticoagulation treatment for women diagnosed with inherited thrombophilia.

Risk factors and role of low molecular weight heparin in obstetric complications among women with inherited thrombophilia - a cohort study

Introduction

Although there is a vast literature regarding the association between inherited thrombophilia, obstetric complications and the effect of low molecular weight heparin (LMWH), these are controversial and we have not found publications related to additional risk factors other than thrombophilia.

Our objectives were to assess the prevalence of miscarriage, placenta-mediated pregnancy complications and fetal loss in pregnant women with IT, establishing associated risk factors and the effect of LMWH.

Materials and methods

A retrospective cohort of pregnant women with IT was formed. Risk factors considered were: high-risk IT, age ≥35 years, body mass index ≥25 and ≥30, assisted reproductive technology, antiphospholipid antibodies, autoimmune disease, first-degree family history of obstetric complications and personal history of venous or arterial thromboembolic disease, the outcomes being M, FL and PMPC.

Results and conclusions

Data from 250 pregnancies in 88 women were obtained.

There were 112 (45%) Ms, 13 (5.2%) FLs and 25 (10%) PMPCs.

High-risk IT was associated with FL (OR = 4.96; 95% CI, 1.42–17.3). Antiphospholipid antibodies and family history of obstetric complications were associated with PMPC (OR = 7.12; 95% CI, 1.89–26.74, OR = 3.88; 95% CI, 1.18–12.78, respectively). The LMWH presented a benefit in the combined outcome (any obstetric complication, OR = 0.25; 95% CI, 0.12–0.54) and M (OR = 0.41; 95% CI, 0.20–0.82).

We conclude that obstetric complications are common in women with IT. Antiphospholipid antibodies, family history of obstetric complications and high-risk IT might be additional risk factors. The LMWH has an apparent protective effect against obstetric complications, which is consistent with some previous studies.

Genetic risk assessment of thrombophilia in patients with adverse obstetric outcomes

OBJECTIVES

To investigate the incidence of inherited thrombophilias in patients with adverse obstetric outcomes and to compare detection rates of thrombophilias between standard blood tests and a novel genetic test.

METHODS

This is a case-control prospective study performed in Hospital Sant Joan de Déu in Barcelona, Spain. Cases had a history of intrauterine growth restriction requiring delivery before 34 weeks gestation, placental abruption before 34 weeks gestation, or severe preeclampsia. Controls had at least two normal, spontaneously conceived pregnancies at term, without complications or no underlying medical disease. At least 3 months after delivery, all case and control women underwent blood collection for standard blood tests for thrombophilias and saliva collection for the genetic test, which enables the diagnosis of 12 hereditary thrombophilias by analyzing genetic variants affecting different points of the blood coagulation cascade.

RESULTS

The study included 33 cases and 41 controls. There were no statistically significant differences between cases and controls in the standard blood tests for thrombophilias in plasma or the TiC test for genetic variables. One clinical-genetic model was generated using variables with the lowest P values: ABO, body mass index, C_rs5985, C_rs6025, and protein S. This model exhibited good prediction capacity, with an area under the curve of almost 0.7 (P <0.05), sensitivity of almost 67%, and specificity of 70%.

CONCLUSION

Although some association may exist between hypercoagulability and pregnancy outcomes, no significant direct correlation was observed between adverse obstetric outcomes and inherited thrombophilias when analyzed using either standard blood tests or the genetic test. Future studies with a larger sample size are required to create a clinical-genetic model that better discriminates women with a history of adverse pregnancy outcomes and an increased risk of poor outcomes in subsequent pregnancies.

The association between IUGR and maternal inherited thrombophilias: A case-control study

One of the risk factors for vascular obstetric complications, such as intrauterine growth restriction (IUGR), is inherited thrombophilias. Nevertheless, routine screening for thrombophilias is not endorsed in pregnant women due to their low prevalence and conflicting results of published studies regarding the usefulness of screening in these patients. The cause of IUGR remains unknown in almost 1 quarter of cases. There are no published studies evaluating the association of inherited thrombophilias and IUGR in patients with IUGR of unknown origin. Understanding and preventing IUGR is an important public health concern, as IUGR has been associated with fetal mortality and neonatal morbidity, as well as adverse long-standing consequences. This study aimed to evaluate the prevalence of inherited thrombophilias in IUGR of unknown cause and to test the association between the inherited thrombophilias and IUGR of unknown cause.This study included 33 cases of IUGR of unknown cause tested for inherited thrombophilias and 66 controls individually matched for age, ethnicity, and smoking status.Patients with plasminogen activator inhibitor 1 (PAI-1) and methylenetetrahydrofolate reductase (MTHFR) had significantly higher odds for IUGR of unknown cause (P < .001 and P = .002, respectively) with OR 13.546 (CI 95% 3.79-48.37) and 8.139 (CI 95% 2.20-30.10), respectively. A positive association between other inherited thrombophilias (homozygous 20210 prothrombin gene mutation and homozygous factor V Leiden) and IUGR of unknown cause was also found, P = .096, OR 6.106 (CI 95% 0.72-51.30), although it was not statistically significant (P = .096, OR = 6.106, CI 95% 0.72-51.30).Our results indicate that PAI-1 and MTHFR thrombophilias represent risk factors for IUGR of otherwise unidentified cause.

Adverse pregnancy outcomes and inherited thrombophilia

AIM

(1) To evaluate the prevalence of inherited thrombophilia in pregnant women with adverse pregnancy outcomes: intrauterine growth retardation (IUGR), preeclampsia (PE) and placental abruption. (2) To assess the impact of inherited thrombophilia on the nature of obstetric complications. (3) To assess levels of protein S, protein C, antithrombin III and homocysteine in pregnant women with adverse pregnancy outcomes.

SUBJECTS AND METHODS

The study comprised 162 pregnant women. The patients were divided into three test groups and one control group. In all 162 patients the following tests were completed: activated protein C resistance (APC-R), the level of free protein S, activity of protein C, antithrombin III and the level of homocysteine. The data were statistically analyzed via χ2 of independence or homogeneity test.

RESULTS

In 32 of 162 patients participating in clinical research thrombophilia was diagnosed (10 patients with APC-R, 21 patients with protein S deficiency, one patient with hyperhomocysteinemia): seven patients belonged to the control group and 25 patients had diagnosed adverse pregnancy outcomes (P=0.04). In 32 patients with diagnosed thrombophilia, level of protein S was decreased (P=0.04). Protein S deficiency was diagnosed, when level of protein S was lower than 30% in the second trimester and lower than 24% in the third trimester. The incidence of activated protein C resistance caused by the mutation of factor V Leiden was in six patients (5.9%) with adverse pregnancy outcomes, and in four patients (6.6%) from the control group. Results were not statistically significant. No protein C deficiency was diagnosed (diagnosis: level<60%), but in 50% of patients with thrombophilia level of protein C was over the norm (P=0.02). The level of antithrombin III was often decreased in patients with preeclampsia - (32.4%), then in the other patients - (17.2%) (P=0.04), but no patient was diagnosed with antithrombin III deficiency (diagnosis: level<60%).

CONCLUSIONS

Tests for thrombophilia should be carried out in women with adverse pregnancy outcomes in their history, who are planning pregnancy, to start anticoagulant prophylaxis. Our study supports the thesis that tests for thrombophilia should be carried out in women with a history of adverse pregnancy outcomes and who are planning a pregnancy to start anticoagulant prophylaxis.

Associations between Maternal and Fetal Inherited Thrombophilias, Placental Characteristics Associated with Vascular Malperfusion, and Fetal Growth

Pregnancy results in alterations in coagulation processes, which may increase the risk of thrombosis. Inherited thrombophilia mutations may further increase this risk, possibly through alterations in the placenta, which may result in pregnancy complications such as poor fetal growth. The purpose of our study is to evaluate the association of fetal growth, approximated by birth weight for gestational age percentile, with genetic markers of thrombophilia and placental characteristics related to vascular malperfusion. We analyzed data from the Stillbirth Collaborative Research Network's population-based case–control study conducted in 2006–2008. Study recruitment occurred in five states: Rhode Island and counties in Massachusetts, Georgia, Texas, and Utah. The analysis was restricted to singleton, nonanomalous live births ≤42 weeks' gestation with a complete placental examination and successful testing for ≥1 thrombophilia marker (858 mothers, 902 infants). Data were weighted to account for oversampling, differential consent, and availability of placental examination. We evaluated five thrombophilia markers: factor V Leiden, factor II prothrombin, methylenetetrahydrofolate reductase A1298C and C677T, and plasminogen activator inhibitor type 1 in both maternal blood and placenta/cord blood. We modeled maternal and fetal thrombophilia markers separately using linear regression. Maternal factor V Leiden mutation was associated with a 13.16-point decrease in adjusted birth weight percentile (95% confidence interval: −25.50, −0.82). Adjustment for placental abnormalities related to vascular malperfusion did not affect the observed association. No other maternal or fetal thrombophilia markers were significantly associated with birth weight percentile. Maternal factor V Leiden may be associated with fetal growth independent of placental characteristics.

Factor V Leiden, prothrombin G20210A, and methylene tetrahydrofolate reductase mutations and stillbirth: the Stillbirth Collaborative Research Network

BACKGROUND

An evaluation for heritable thrombophilias is recommended in the evaluation of stillbirth. However, the association between thrombophilias and stillbirth remains uncertain.

OBJECTIVE

We sought to assess the association between maternal and fetal/placental heritable thrombophilias and stillbirth in a population-based, case-control study in a geographically, racially, and ethnically diverse population.

STUDY DESIGN

We conducted secondary analysis of data from the Stillbirth Collaborative Research Network, a population-based case-control study of stillbirth. Testing for factor V Leiden, prothrombin G20210A, methylene tetrahydrofolate reductase C677T and A1298C, and plasminogen activating inhibitor (PAI)-1 4G/5G mutations was done on maternal and fetal (or placental) DNA from singleton pregnancies. Data analyses were weighted for oversampling and other aspects of the design. Odds ratios (OR) were generated from univariate models regressing stillbirth/live birth status on each thrombophilia marker.

RESULTS

Results were available for ≥1 marker in 488 stillbirths and 1342 live birth mothers and 405 stillbirths and 990 live birth fetuses. There was an increased odds of stillbirth for maternal homozygous factor V Leiden mutation (2/488; 0.4% vs 1/1380; 0.0046%; OR, 87.44; 95% confidence interval, 7.88-970.92). However, there were no significant differences in the odds of stillbirth for any other maternal thrombophilia, even after stratified analyses. Fetal 4G/4G PAI-1 (OR, 0.63; 95% confidence interval, 0.43-0.91) was associated with decreased odds of stillbirth. Other fetal thrombophilias were similar among groups.

CONCLUSION

Most maternal and fetal thrombophilias were not associated with stillbirth. Maternal factor V Leiden was weakly associated with stillbirth, and the fetal PAI-1 4G/4G polymorphism was associated with live birth. Our data do not support routine testing for heritable thrombophilias as part of an evaluation for possible causes of stillbirth.

Birthweight in pregnant women with protein S deficiency treated with low-molecular-weight heparin: a retrospective cohort study

OBJECTIVE

To determine the risk of small-for-gestational-age (SGA) and intrauterine growth retardation (IUGR) in pregnant women with protein S (PS) deficiency who received low-molecular-weight heparin (LMWH).

METHODS

Retrospective cohort study of pregnant women seen from January 2002 to December 2011. The study cohort comprised a total of 328 patients with PS deficiency, who received prophylactic enoxaparin during pregnancy. The control cohort included 11 884 pregnant women without significant past medical history. The risk of SGA and IUGR was calculated as odds ratio. Multivariate regression analysis over the entire reference population was performed determining the risk of both SGA and IUGR by adjusting for maternal age, first delivery, maternal underweight status, pre-eclampsia, other treated thrombophilias or history of recurrent abortion.

RESULTS

The SGA rates in the PS deficiency and control cohorts were 10.7% and 8.5%, respectively (p > 0.05). There was no increased risk of SGA (unadjusted OR = 1.28, 95% confidence interval [CI] 0.9-1.83; adjusted OR = 1.35, 95% CI 0.91-2.01). The IUGR rate was 2.7% in pregnant women with PS deficiency versus 4.1% in the control group (p > 0.05). Also, we did not find a significant risk of IUGR (OR = 0.66; 95% CI 0.34-1.28; adjusted OR = 0.843; 95% CI 0.42-1.70).

CONCLUSIONS

In women with PS deficiency treated with LMWH, the risk of SGA and IUGR is similar to the one found in healthy pregnant women.

A critical analysis of low molecular weight heparin use during pregnancy in a tertiary referral centre

The aim of this study was to analyse low molecular weight heparin (LMWH) use during pregnancy in terms of patient evaluation, treatment indication and social and financial costs. This was a retrospective analysis of patients using LMWH in their pregnancies. A total of 147 women were included in the study. The most common indications were thrombophilia (55/147, 37.4%); recurrent pregnancy loss (RPL); (47/147, 32.0%) and previous single pregnancy loss (18/147, 12.2%). In the RPL group, 53.1% of patients were not evaluated with standard tests; 31.9% of women were incompletely evaluated and 15% were properly evaluated. Out of 104 women screened for thrombophilia, 32 (32/104, 30.8%) were tested during pregnancy. Despite published guidelines and increasing scientific evidence against their use in some indications, LMWHs are prescribed widely during pregnancy for a variety of indications. Public and healthcare providers' education to change this attitude should be implemented.

Polymorphisms of the methylenetetrahydrofolate reductase gene (C677T and A1298C) in nulliparous women complicated with preeclampsia

OBJECTIVE

To determine the prevalence of C677T and A1298C Single-nucleotide polymorphisms (SNPs) of the MTHFR gene in nulliparous women complicated with preeclampsia (PE).

METHODS

One hundred fifty gestations complicated with PE and their corresponding controls without the disease were recruited for the genotyping of C677T and A1298C polymorphisms of the MTHFR gene using restriction fragment length polymorphism polymerase chain reaction. Secondarily, homocysteine (HCy) plasma levels were measured in preeclamptic women displaying the CC genotype of the A1298C polymorphism (homozygous) and compared to HCy levels determined among controls with the normal AA genotype for the A1298C variant.

RESULTS

Only the mutant CC genotype of the A1298C polymorphism was associated to higher risk of presenting PE, as frequency of this genotype was significantly higher among cases than controls (15.3% versus 0.7%, p < 0.05). All PE women with a neck circumference ≥32 cm presented the mutant CC A1298C polymorphism as compared to none among preeclamptics with a lower neck circumference (p = 0.0001). Women with the mutant CC A1298C SNP displayed higher plasma HCy levels as compared to controls with normal AA A1298C genotype (8.4 ± 2.6 versus 7.5 ± 2.7 mmoL/L p = 0.04).

CONCLUSION

Prevalence of the CC mutant genotype of the A1298C polymorphism was higher among PE women. This mutation among PE women was related to increased neck circumference and higher HCy levels. Future research should aim at linking these gestational findings with obesity and cardiovascular risk.

Associations of MTHFR gene polymorphisms with hypertension and hypertension in pregnancy: a meta-analysis from 114 studies with 15411 cases and 21970 controls

BACKGROUND

Several epidemiological studies have investigated the associations of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms with hypertension (H) or hypertension in pregnancy (HIP). However, the results were controversial. We therefore performed a comprehensive meta-analysis to provide empirical evidences on the associations.

METHODOLOGIES

The English and Chinese databases were systematically searched to identify relevant studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the associations. Meta-regression, subgroup analysis, sensitivity analysis, cumulative meta-analysis and assessment of publication bias were performed in our study.

PRINCIPAL FINDINGS

A total of 114 studies with 15411 cases and 21970 controls were included, 111 studies with 15094 cases and 21633 controls for the C677T polymorphism and 21 with 2533 cases and 2976 controls for the A1298C polymorphism. Overall, the C677T polymorphism was significantly associated with H and HIP (H & HIP: OR = 1.26, 95% CI = 1.17-1.34; H: OR = 1.36, 95% CI = 1.20-1.53; HIP: OR = 1.21, 95% CI = 1.08-1.32). Stratified analysis by ethnicity revealed a significant association among East Asians and Caucasians, but not among Latinos, Black Africans, and Indians and Sri Lankans. In the stratified analyses according to source of controls, genotyping method, sample size and study quality, significant associations were observed in all the subgroups, with the exception of population based subgroup in H studies and large sample size and "others" genotyping method subgroups in HIP studies. For the A1298C polymorphism, no significant association was observed either in overall or subgroup analysis under all genetic models.

CONCLUSIONS

This meta-analysis suggests that the MTHFR C677T rather than A1298C polymorphism may be associated with H & HIP, especially among East Asians and Caucasians.

Inherited thrombophilia: diagnosis and anticoagulation treatment in pregnancy

The association between inherited thrombophilia and deep vein thrombosis is well established. Adverse pregnancy outcomes, sometimes called placenta-mediated complications, have been attributed to excessive thrombosis and inflammation at the uteroplacental interface. This linkage resulted in widespread screening for thrombophilia in women with adverse pregnancy outcome. Anticoagulant therapy was initially liberally administered for prevention of adverse pregnancy outcome. Well-designed randomized trials were initiated and the results of some of these randomized trials have provided critical evidence-based data to serve as a guide for clinicians faced with managing patients with one or more of the common obstetric complications.

Methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism and risk of preeclampsia: an updated meta-analysis based on 51 studies

BACKGROUND AND AIMS

The methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism has been considered to be associated with preeclampsia (PE), but the results from previous studies were conflicting. The present study aimed at investigating the frequency of preeclampsia according to the distribution polymorphism using a meta-analysis on the published studies.

METHODS

The English and Chinese databases were searched to identify eligible studies published in English before August 2012. Data were extracted using standardized methods. The association was assessed by odds ratio (OR) with 95% confidence intervals (CI). Begg's test was used to measure publication bias.

RESULTS

A total of 51 case-control studies containing 6,403 patients and 11,346 controls were involved in this meta-analysis. Significant associations were detected between MTHFR C677T polymorphism and risk of PE in the overall population for TT vs. CC (OR = 1.280, 95% CI: 1.074-1.525), recessive model (OR = 1.264, 95% CI: 1.067-1.303), and dominant genetic model (OR = 1.174, 95% CI: 1.057-1.303); in Caucasian population for dominant model (OR = 1.136, 95% CI: 1.022-1.263), and in East Asia population for TT vs. CC (OR = 2.199, 95% CI: 1.366-3.924) CT vs. CC (OR = 1.453, 95% CI: 1.001-2.109), recessive model (OR = 1.742, 95% CI: 1.202-2.525), and dominant model (OR = 1.783, 95% CI: 1.271-2.501). Conversely, no associations were detected in Latin America, South Asia, and Africa populations.

CONCLUSIONS

Results of the meta-analysis suggest that the MTHFR C677T polymorphism was associated with risk of PE in overall, Caucasian, and East Asia populations. Nevertheless, the results for Latino, East Asians, South Asians and Africans should be interpreted with caution due to the small sample size.

Analysis of polymorphisms and haplotypes in genes associated with vascular tone, hypertension and oxidative stress in Mexican-Mestizo women with severe preeclampsia

OBJECTIVE

Several studies have reported the association of genes related to vascular tone, hypertension, oxidative stress and preeclampsia. We investigated the possible association among three polymorphisms in eNOS (as well their haplotypes): one of MTHFR, one of GSTP1 and one of AGT, with severe preeclampsia in Mexican-Mestizo women.

METHODS

Two hundred thirty women with severe preeclampsia and 350 control subjects were genotyped; for rs2070744 and rs1799983 of eNOS, rs1801133 of MTHFR, rs1695 of GSTP1 and rs699 of AGT we used real-time PCR allelic discrimination and for VNTR of eNOS, PCR. Allele frequency differences were assessed by χ(2). Logistic regression was used to test for associations and for haplotype frequencies using Haploview 4.2.

RESULTS

Genotypic and allelic distribution of the polymorphisms was similar between cases and controls; likewise, haplotype frequencies of the three polymorphisms of eNOS did not differ significantly.

CONCLUSIONS

To our knowledge, this is the first time that these polymorphisms have been analyzed together and exclusively in women with severe preeclampsia. However, we did not find an association between polymorphisms of eNOS, MTHFR, GSTP1 and AGT with severe preeclampsia in our population. Additionally, we observed differences in the distribution of the alleles and genotypes of these polymorphisms in our population in comparison to those described in other ethnic groups.