Preeclampsia and its interaction with common variants in thrombophilia genes

The Role of Plasminogen Activator Inhibitor Type 1 (PAI-1) in Placenta-Mediated Pregnancy Complications: A Systematic Review

Plasminogen activator inhibitor type 1 (PAI-1) is a main inhibitor of fibrinolysis. The PAI-1 gene (SERPINE1) harbors genetic variants with the potential of modifying plasma levels of PAI-1. A delicate balance exists between the coagulation and fibrinolytic system, and changes in PAI-1 have been suggested to compromise establishment of a successful pregnancy. Therefore, this systematic review investigated the association between genetic variants and/or plasma levels of PAI-1 and placenta-mediated pregnancy complications. An extensive literature search was conducted in PubMed, Embase, and Web of Science on the 29^th of April 2021. All studies underwent quality rating according to The Study Quality Assessment Tools checklist provided by National Heart, Lung and Blood Institute. A total of 71 studies were included, among which 60 studies investigated PAI-1 genotypes and 11 studies measured PAI-1 plasma levels. In 32 out of 59 studies, no association was found between the PAI-1 4G/5G polymorphism (rs1799768) and placenta-mediated pregnancy complications, which was stated as no significant difference in the genotype distribution comparing women with and without placenta-mediated pregnancy complications or no significantly increased odds of placenta-mediated pregnancy complications carrying the 4G/4G or 4G/5G genotype. Eight out of 11 studies reported significantly higher PAI-1 plasma levels in preeclamptic women than in women without preeclampsia. In conclusion, no clear evidence indicates that PAI-1 polymorphisms are associated with placenta-mediated pregnancy complications, and the possible association between high PAI-1 plasma levels and preeclampsia needs further investigations. Thus, investigation of PAI-1 genotypes and PAI-1 plasma levels does not currently seem to have a place in daily clinical practice managing placenta-mediated pregnancy complications.

A narrative review on the role of folate-mediated one-carbon metabolism and its associated gene polymorphisms in posing risk to preeclampsia

Preeclampsia (PE) presents a major obstetrical problem for mother and fetus which is characterized by the onset of hypertension and proteinuria in formerly normotensive women. Altered folate-mediated one-carbon metabolism is one of the factors for PE development either due to nutritional insufficiencies such as folate deficiency or polymorphisms in genes that code for the key enzymes of the cycle. Commonly, there are four genes in the cycle whose polymorphisms have been described in relation to PE. These factors could cause elevation of homocysteine; the toxic metabolite, which subsequently leads to the development of PE. Sufficient levels of folate have been considered important during pregnancy and may reduce the risk of development of PE. This review aims at discussing genetic polymorphisms and nutritional deficiencies as probable predisposing factors and suggests considering fetal genotypes, varied ethnicities, and interaction of various other factors involved to render better conclusiveness to the present studies.

Hemostasis-related gene polymorphisms and their epistatic relationship in women with idiopathic infertility

: A numerous factor can cause infertility, but around one of four reproductive failure cases remain unexplained and diagnosed as idiopathic infertility. In the past few decades, analysis of gene polymorphisms takes a significant place in pathogenesis of infertility. The aim of this study was to evaluate the possible role of hemostasis-related gene polymorphisms in unexplained infertility. The study includes 117 female patients with idiopathic infertility and 130 fertile women with at least one born child. Eight polymorphisms important for hemostasis (ITGB3 1565T>C, FV 1691G>A, FII 20210G>A, MTHFR 677C>T and 1298A>C, ATIII 786G>A, PAI-14G/5G and ACE I/D) were genotyped by real-time PCR system. The frequencies of alleles and genotypes of examined polymorphisms were analyzed in SPSS statistical program, whereas gene interactions were identified using the GMDR software. Examination of etiological factors has shown that family history is a significant factor in assessing individual risk for infertility. The alleles and genotypes frequency of FV 1691G>A and FII 20210G>A polymorphisms were statistically different between control and patient group leading to a greater risk for infertility. The analysis of epistatic relationship between examined hemostasis-related gene polymorphisms identified more complex high-risk genotypes associated with infertility. Our results suggest that positive family history could be important predictive factor for fertility problems, pointing to the potential hereditary basis of this condition. Polymorphisms FVL and FII prothrombin are independent risk factors for idiopathic infertility, whereas multilocus interactions approach should be taken into consideration for the future research.

Circulating microparticle proteins obtained in the late first trimester predict spontaneous preterm birth at less than 35 weeks' gestation: a panel validation with specific characterization by parity

BACKGROUND

We have previously shown that protein biomarkers associated with circulating microparticles proteins (CMPs) obtained at the end of the first trimester may detect physiologic changes in maternal-fetal interaction such that the risk of spontaneous preterm delivery ≤35 weeks can be stratified.

OBJECTIVES

We present here a study extension and validation of the CMP protein multiplex concept using a larger sample set from a multicenter population that allows for model derivation in a training set and characterization in a separate testing set.

MATERIALS AND METHODS

Ethylenediaminetetraacetic acid (EDTA) plasma was obtained from 3 established biobanks (Seattle, Boston, and Pittsburgh). Samples were from patients at a median of 10-12 weeks' gestation, and the CMPs were isolated via size-exclusion chromatography followed by protein identification via targeted protein analysis using liquid chromatography-multiple reaction monitoring-mass (LC-MRM) spectrometry. A total of 87 women delivered at ≤35 weeks, and 174 women who delivered at term were matched by maternal age (±2 years) and gestational age at sample draw (±2 weeks). From our prior work, the CMP protein multiplex comprising F13A, FBLN1, IC1, ITIH2, and LCAT was selected for validation.

RESULTS

For delivery at ≤35 weeks, the receiver operating characteristic (ROC) curve for a panel of CMP proteins (F13A, FBLN1, IC1, ITIH2, and LCAT) revealed an associated area under the ROC curve (AUC) of 0.74 (95% CI, 0.63-0.81). A separate panel of markers (IC1, LCAT, TRFE, and ITIH4), which stratified risk among mothers with a parity of 0, showed an AUC of 0.77 (95% CI, 0.61-0.90).

CONCLUSION

We have identified a set of CMP proteins that provide, at 10-12 weeks gestation, a clinically useful AUC in an independent test population. Furthermore, we determined that parity is pertinent to the diagnostic testing performance of the biomarkers for risk stratification.

Cardiovascular risk factors in women with inheritable thrombophilia a decade after single or recurrent hypertensive disorder of pregnancy

OBJECTIVE

To described cardiovascular risk factors in women with inheritable thrombophilia 8-19 years after early-onset hypertensive disorders of pregnancy (HD) with or without recurrent HD.

METHODS

Women with recurrent HD were compared with women with single HD, for physical examination and cardiovascular parameters in serum.

RESULTS

Systolic blood pressure, diastolic blood pressure, and albumin: creatinine ratio were higher in women with recurrent HD compared with women with single HD (p = 0.046, p = 0.029, and p = 0.008, respectively). In both groups 72.7% had an increased cardiovascular risk.

CONCLUSION

Women with inheritable thrombophilia after single or recurrent HD have a high cardiovascular risk.

Folate metabolism gene polymorphisms MTHFR C677T and A1298C and risk for preeclampsia: a meta-analysis

OBJECTIVES

MTHFR C677T and A1298C have been associated with the risk of preeclampsia (PE), but with conflicting results. We performed this meta-analysis to derive a more precise estimation of the association between MTHFR polymorphisms and PE.

STUDY DESIGN

An electronic search of PubMed and Chinese Biomedicine database was conducted to select studies for meta-analysis. 54 case controlled studies containing MTHFR C677T and A1298C gene polymorphisms were chosen, and odds ratio (OR) with confidence interval (CI) was used to assess the strength of this association.

RESULT

These studies evaluated 7398 cases and 11230 controls for MTHFR C677T. The overall results suggested that MTHFR C677T was associated with the risk of PE. (T vs. C: OR = 1.157, 95% CI: 1.057-1.266, p = 0.002; TT + CT vs. CC: OR = 1.165, 95% CI : 1.049-1.293, P = 0.004; TT vs. CT + CC: OR = 1.371, 95% CI: 1.153-1.63, p < 0.001). We also evaluated 1103 cases and 988 controls for MTHFR A1298C but could not demonstrate an increased risk of PE for this polymorphism (p = 0.667). A symmetric funnel plot, the Egger's test (p = 0.819) suggested a lack of publication bias.

CONCLUSION

This meta-analysis supports the idea that MTHFR C677T genotype is associated with increased risk for PE, especially in the case of Asians and Caucasians.

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.

Pregnancy and thrombophilia

The physiological changes that occur during pregnancy create a hypercoagulable milieu. This hypercoagulable state is thought to be protective, especially at the time of labor, preventing excessive hemorrhage. The presence of hereditary or acquired causes of thrombophilia during pregnancy tilts the balance in favor of unwanted venous thromboembolism and adverse pregnancy outcomes due to vascular uteroplacental insufficiency. These adverse pregnancy outcomes include recurrent pregnancy losses, intrauterine fetal death, intrauterine growth retardation, preeclampsia and placental abruption. Much of the current data with regards to the association of the different thrombophilias and pregnancy-related complications are based on retrospectively designed studies. This lack of randomization, in-homogeneity of patient populations, varying case definitions, selection biases and inadequately matched control populations, have given rise to conflicting data with regard to screening for, and treatment of, pregnant women with suspected thrombophilias. The limited data that we have support the use of anticoagulant drugs for the prevention of pregnancy-related complications in the setting of thrombophilia. Heparin and low-molecular-weight heparins are the anticoagulant drugs of choice as they do not cross the placental barrier and, hence, do not cause fetal anticoagulation or teratogenicity. Warfarin can be used from the 12th week of gestation onwards but is preferably reserved for the postpartum period.

Levels of thrombin activatable fibrinolysis inhibitor in gestational diabetes mellitus

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a procarboxypeptidase, which is synthesised in liver and activated by thrombin and the thrombin-thrombomodulin complex. TAFI suppresses fibrinolysis by removing carboxy-terminal lysine residues from partially degraded fibrin. In this study we aimed to assess the circulating levels of TAFI antigen, 'a fibrinolytic parameter' in women with gestational diabetes (GDM). Thirty-four pregnant women with GDM and 50 pregnant women with normal glucose tolerance were included in the study. Plasma TAFI antigen levels were significantly higher in pregnant women with GDM when compared with controls. Increased TAFI levels may contribute to the decreased fibrinolytic potency, causing a thrombophilic state. GDM is regarded as a specific form of diabetes, and it could in addition be a predictor of type 2 diabetes mellitus in the future and the risk of complications due to hypercoagulability increases in this disease. Increased TAFI levels may also have a role in increased risk of hypercoagulability.

Association of plasminogen activator inhibitor-type 1 (-675 4G/5G) polymorphism with pre-eclampsia: systematic review

BACKGROUND AND AIMS

Excessive generation of plasminogen activator inhibitor-type 1 (PAI-1) is implicated in the pathogenesis of pre-eclampsia and related conditions. The PAI-1 (-675 4G/5G) promoter polymorphism (rs1799889) affects transcriptional activity and is a putative genetic risk factor for pre-eclampsia. The aim of this study was identify, appraise and synthesise the available evidence for the association of the PAI-1 (-675 4G/5G) polymorphism with pre-eclampsia.

METHODS

Systematic review and random effects meta-analysis of genetic association studies.

RESULTS

We found 12 eligible genetic association studies in which a total of 1511 women with pre-eclampsia, eclampsia or HELLP syndrome and 3492 controls participated. The studies were generally small (median number of cases 102, range 24 to 403) and underpowered to detect plausible association sizes. Meta-analysis of all of the studies detected statistically significant gene-disease associations in the recessive [pooled odds ratio 1.28 (95% confidence interval 1.09, 1.50); population attributable risk 7.7%] and dominant [pooled odds ratio 1.21 (95% confidence interval 1.01, 1.44); population attributable risk 13.7%] models. We did not find evidence of statistical heterogeneity, funnel plot asymmetry or small study bias.

CONCLUSIONS

These data suggest that the fibrinolytic pathway regulated by the PAI-1 gene may contribute to the pathogenesis of pre-eclampsia and related conditions. This association, if confirmed in larger genetic association studies, may inform research efforts to develop novel interventions or help to prioritise therapeutic targets that merit evaluation in randomised clinical trials.

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.

Preeclampsia and ABO blood groups: a systematic review and meta-analysis

Preeclampsia (PE) is a multifactorial pregnancy-specific syndrome which represents one of the leading causes of maternal mortality worldwide. Inherited thrombophilia have been investigated as risk factor for the development of PE and it is currently known that ABO blood group may impact haemostatic balance, having the non-O blood groups (A, B or AB) subjects increased risk for thrombus formation, as compared to those of group O. We performed a systematic review of the literature for published studies investigating whether ABO blood groups could influence PE developing. A sensitive search of four databases identified 45 unique titles. The retrieved papers were assessed independently by authors and a rigorous process of selection and data extract was conduct. Methodological quality of the included studies was also evaluated. Two studies met eligibility criteria. As a main finding of our systematic review, an association between the AB blood group and the occurrence of PE was detected based on two original studies. Considering the role of ABO blood groups on the hemostatic process and thrombus formation, special attention should be given to pregnant patients carrying the AB blood group in order to prevent the syndrome and improve prognosis.

Association between the SERPINE1 (PAI-1) 4G/5G insertion/deletion promoter polymorphism (rs1799889) and pre-eclampsia: a systematic review and meta-analysis

The SERPINE1 -675 4G/5G promoter region insertion/deletion polymorphism (rs1799889) has been implicated in the pathogenesis of pre-eclampsia (PE), but the genetic association has been inconsistently replicated. To derive a more precise estimate of the association, a systematic review and meta-analysis was conducted. This study conformed to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed (MEDLINE), Scopus and HuGE Literature Finder literature databases were systematically searched for relevant studies. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for the allelic comparison (4G versus 5G) and genotypic comparisons following the co-dominant (4G/4G versus 5G/5G and 4G/5G versus 5G/5G), dominant (4G/4G+4G/5G versus 5G/5G) and recessive (4G/4G versus 4G/5G+5G/5G) genetic models. Between-study heterogeneity was quantified by I(2) statistics and publication bias was appraised with funnel plots. Sensitivity analysis was conducted to evaluate the robustness of meta-analysis findings. Meta-analysis of 11 studies involving 1297 PE cases and 1791 controls found a significant association between the SERPINE1 -675 4G/5G polymorphism and PE for the recessive genetic model (OR = 1.36, 95% CI: 1.13-1.64, P = 0.001), a robust finding according to sensitivity analysis. A low level of between-study heterogeneity was detected (I(2) = 20%) in this comparison, which may be explained by ethnic differences. Funnel plot inspection did not reveal evidence of publication bias. In conclusion, this study provides a comprehensive examination of the available literature on the association between SERPINE1 -675 4G/5G and PE. Meta-analysis results support this polymorphism as a likely susceptibility variant for PE.

Association between genotype and plasma levels of thrombin-activated fibrinolysis inhibitor (TAFI) in the development of preeclampsia

INTRODUCTION

The objective was to evaluate if thrombin-activated fibrinolysis inhibitor (TAFI) polymorphisms (G505A, C1040T, and G-438A), and TAFIa plasma levels are associated with preeclampsia.

MATERIALS AND METHODS

In a case-control study design, we evaluated preeclampsia patients and women with uncomplicated pregnancies. The TAFI polymorphisms were determined by real-time PCR method, and TAFIa plasma levels were established with a chromogenic assay.

RESULTS

We included 87 women in each group. The TAFIa levels in the preeclampsia group were 20.4 μg/mL (CI 95% 17.3-23.5), while in the control group, they were significantly lower: 13.3 μg/mL (12.0-14.5, p 0.003). There were no differences in the genotype distribution or allelic frequency of TAFI polymorphisms between the two groups. In preeclampsia patients and controls heterozygous for the G505A polymorphism, the TAFIa values were 22.8 (16.7-28.9 μg/mL) and 13.2 (11.3-15.0 μg/mL, p 0.019), respectively. In G505A homozygous polymorphism the TAFIa values were 25.7 (18.7-32.6 μg/mL) and 13.5 (1.6-21.9 μg/mL, p 0.041), respectively. In the C1040T and G-438A TAFI wild type polymorphisms, the TAFIa values were 18.3 (12.5-23.9 μg/mL) and 11.5 (9.9-35.0, p 0.033), and 19.4 (10.9-27.9 μg/mL) and 12.5 (10.8-14.2 μg/mL, p 0.006), respectively, without differences in other genotypes.

CONCLUSIONS

Preeclampsia by itself may be responsible for the increase in TAFIa values rather than the presence of polymorphisms.

Thrombophilia risk factors are associated with intrauterine foetal death and pregnancy-related venous thromboembolism

Pregnancy in healthy women is accompanied by hypercoagulable changes that may interact with thrombophilia risk factors and threaten pregnancy. However, the literature on this issue is conflicting. In investigating the relationship between pregnancy-associated complications and the presence of thrombophilia risk factors, we studied the records of 414 women who had been examined for inherited and acquired thrombophilia in the period 1996 to 2006 because of pregnancy-associated complications. Of a total of 885 pregnancies among the women, 397 were recorded as foetal loss/intrauterine foetal death during the first (62 %), second (25 %) or third trimester (13 %). One-hundred-and-two (25 %) women had had a thromboembolic event during one of their pregnancies, and 98 (24 %) had had pre-eclampsia on at least one occasion. Intrauterine growth restriction was found in 105 (25 %) of the women, and 29 (7 %) suffered placental abruption. We found that 120 (29 %) women had at least one thrombophilia risk factor. Factor V Leiden heterozygosity was the most common thrombophilia factor (n = 52), mostly linked with the risk of venous thromboembolism during pregnancy or postpartum and to foetal death during the second or third trimester. Fifty-three (13 %) women had antiphospholipid antibodies (lupus anticoagulant and/or anti-beta2-glycoprotein 1 antibodies) mainly associated with the risk of spontaneous abortion during the first trimester. In conclusion, thrombophilia was found to be considerably more common in women with pregnancy-associated complications in comparison with the general population, and most frequently in conjunction with venous thromboembolism during pregnancy and the postpartum period.

Methylenetetrahydrofolate reductase C677T and glutathione S-transferase P1 A313G are associated with a reduced risk of preeclampsia in Maya-Mestizo women

Preeclampsia, a common complication of pregnancy, is characterized by elevated blood pressure and proteinuria developing after 20 weeks' gestational age. Susceptibility to this syndrome is believed to have a genetic component. The aim of this study was to investigate whether or not the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T and glutathione S-transferase P1 (GSTP1) A313G polymorphisms are associated with preeclampsia in Maya-Mestizo women. A case-control study was performed, in which 125 preeclamptic patients and 274 healthy controls were genotyped for the MTHFR C677T and GSTP1 A313G polymorphisms by real-time PCR allelic discrimination. Allele and genotype frequencies were compared using the chi2 tests. The MTHFR 677T allele and the 677TT genotype were significantly more frequent in the controls, suggesting an association with a decreased risk of preeclampsia (p = 0.017 and p = 0.007, respectively). Similarly, GSTP1 313GG/GC genotypes and the G allele were more frequent in controls, showing a significant association with reduced risk of preeclampsia (p = 0.008 and p = 0.013, respectively). Our results suggest, for the first time, that the MTHFR 677T and GSTP1 313G polymorphisms confer a significantly decreased risk of developing preeclampsia in the Mexican Maya-Mestizo population.

Thrombin-activatable fibrinolysis inhibitor polymorphisms and recurrent pregnancy loss

OBJECTIVE

To investigate the possible association between selected thrombin-activatable fibrinolysis inhibitor (TAFI) single nucleotide polymorphisms (SNPs) and recurrent pregnancy loss (RPL).

DESIGN

Case-control study.

SETTING

University hospital.

PATIENT(S)

One hundred fifty-eight women (86 cases and 72 controls).

INTERVENTION(S)

Determination of TAFI SNPs -438A/G, +505A/G, +1040T/C, +1542C/G, and +1583A/T by polymerase chain reaction (PCR) reactions and sequencing analysis performed on peripheral blood samples.

MAIN OUTCOME MEASURE(S)

Analysis of the genotype and allele frequencies of TAFI SNPs -438A/G, +505A/G, +1040T/C, +1542C/G, and +1583A/T in women with and without RPL.

RESULT(S)

Genotype and allele frequencies of TAFI +505 and +1583 SNPs were significantly different in women with RPL compared with control women. The frequencies of the +505A/A and +505G/G genotypes were 1.2% and 61.6% in women with RPL and 13.9% and 43.1% in control women, respectively. The frequencies of the +1583A/A and +1583T/T genotypes were 1.2% and 61.6% in women with RPL and 13.9% and 45.8% in control women, respectively. The genotype and allele frequencies at TAFI position -438, +1040, and +1542 were not significantly different between RPL and control women.

CONCLUSION(S)

The SNPs leading to increased TAFI levels are associated with a reduced risk of RPL. It is possible that TAFI is involved in RPL.

Venous thromboembolism, thrombophilia, antithrombotic therapy, and pregnancy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

This article discusses the management of venous thromboembolism (VTE) and thrombophilia, as well as the use of antithrombotic agents, during pregnancy and is part of the American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that benefits do, or do not, outweigh risks, burden, and costs. Grade 2 recommendations are weaker and imply that the magnitude of the benefits and risks, burden, and costs are less certain. Support for recommendations may come from high-quality, moderate-quality or low-quality studies; labeled, respectively, A, B, and C. Among the key recommendations in this chapter are the following: for pregnant women, in general, we recommend that vitamin K antagonists should be substituted with unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) [Grade 1A], except perhaps in women with mechanical heart valves. For pregnant patients, we suggest LMWH over UFH for the prevention and treatment of VTE (Grade 2C). For pregnant women with acute VTE, we recommend that subcutaneous LMWH or UFH should be continued throughout pregnancy (Grade 1B) and suggest that anticoagulants should be continued for at least 6 weeks postpartum (for a total minimum duration of therapy of 6 months) [Grade 2C]. For pregnant patients with a single prior episode of VTE associated with a transient risk factor that is no longer present and no thrombophilia, we recommend clinical surveillance antepartum and anticoagulant prophylaxis postpartum (Grade 1C). For other pregnant women with a history of a single prior episode of VTE who are not receiving long-term anticoagulant therapy, we recommend one of the following, rather than routine care or full-dose anticoagulation: antepartum prophylactic LMWH/UFH or intermediate-dose LMWH/UFH or clinical surveillance throughout pregnancy plus postpartum anticoagulants (Grade 1C). For such patients with a higher risk thrombophilia, in addition to postpartum prophylaxis, we suggest antepartum prophylactic or intermediate-dose LMWH or prophylactic or intermediate-dose UFH, rather than clinical surveillance (Grade 2C). We suggest that pregnant women with multiple episodes of VTE who are not receiving long-term anticoagulants receive antepartum prophylactic, intermediate-dose, or adjusted-dose LMWH or intermediate or adjusted-dose UFH, followed by postpartum anticoagulants (Grade 2C). For those pregnant women with prior VTE who are receiving long-term anticoagulants, we recommend LMWH or UFH throughout pregnancy (either adjusted-dose LMWH or UFH, 75% of adjusted-dose LMWH, or intermediate-dose LMWH) followed by resumption of long-term anticoagulants postpartum (Grade 1C). We suggest both antepartum and postpartum prophylaxis for pregnant women with no prior history of VTE but antithrombin deficiency (Grade 2C). For all other pregnant women with thrombophilia but no prior VTE, we suggest antepartum clinical surveillance or prophylactic LMWH or UFH, plus postpartum anticoagulants, rather than routine care (Grade 2C). For women with recurrent early pregnancy loss or unexplained late pregnancy loss, we recommend screening for antiphospholipid antibodies (APLAs) [Grade 1A]. For women with these pregnancy complications who test positive for APLAs and have no history of venous or arterial thrombosis, we recommend antepartum administration of prophylactic or intermediate-dose UFH or prophylactic LMWH combined with aspirin (Grade 1B). We recommend that the decision about anticoagulant management during pregnancy for pregnant women with mechanical heart valves include an assessment of additional risk factors for thromboembolism including valve type, position, and history of thromboembolism (Grade 1C). While patient values and preferences are important for all decisions regarding antithrombotic therapy in pregnancy, this is particularly so for women with mechanical heart valves. For these women, we recommend either adjusted-dose bid LMWH throughout pregnancy (Grade 1C), adjusted-dose UFH throughout pregnancy (Grade 1C), or one of these two regimens until the thirteenth week with warfarin substitution until close to delivery before restarting LMWH or UFH) [Grade 1C]. However, if a pregnant woman with a mechanical heart valve is judged to be at very high risk of thromboembolism and there are concerns about the efficacy and safety of LMWH or UFH as dosed above, we suggest vitamin K antagonists throughout pregnancy with replacement by UFH or LMWH close to delivery, after a thorough discussion of the potential risks and benefits of this approach (Grade 2C).

Genes and the preeclampsia syndrome

Preeclampsia is specific to pregnancy and is still a leading cause of maternal and perinatal mortality and morbidity, affecting about 3% of women, but the underlying pathogenetic mechanisms still remain unclear. Immune maladaptation, placental ischemia and increased oxidative stress represent the main components discussed to be of etiologic importance, and they all may have genetic implications. Since the familial nature of preeclampsia is known for many years, extensive research on the genetic contribution to the pathogenesis of this severe pregnancy disorder has been performed. In this review, we will overview the linkage and candidate gene studies carried out so far as well as summarize important historical notes on the genetic hypotheses generated in preeclampsia research. Moreover, the influence of maternal and fetal genes and their interaction as well as the role of genomic imprinting in preeclampsia will be discussed.

The 4G/5G polymorphism in the plasminogen activator inhibitor-1 gene is not associated with HELLP syndrome

Plasminogen activator inhibitor-1 (PAI-1) is a major inhibitor of fibrinolysis, and a single nucleotide insertion/deletion (4G/5G) polymorphism in the promoter region of the PAI-1 gene has been identified. Subjects homozygous for the 4G allele have the highest PAI-levels due to increased PAI-1 gene transcription. Pre-eclampsia, and one of its most severe forms, the HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome, are characterized by increased placental thrombosis based on a procoagulatory state in the mother. Several studies have investigated the role of the PAI-1 4G/5G polymorphism in pre-eclampsia, but no study has focused especially on HELLP syndrome. Therefore we aimed to assess the association between HELLP syndrome and the 4G/5G polymorphism in the PAI-1 gene. Genotyping of the PAI-1 4G/5G promoter polymorphism was performed in 102 Caucasian women with HELLP syndrome and 102 Caucasian women with uncomplicated pregnancies. The 4G/4G genotype was more frequent in women with HELLP syndrome than in controls (35.3% vs. 22.5%, respectively) but this difference was not significantly different (P = 0.129). The frequency of the 4G allele was 0.588 in patients and 0.515 in controls. These data suggest that women carrying a 4G/4G genotype of the PAI-1 gene are not at increased risk for developing HELLP syndrome and are thus in line with the majority of previous studies on the association between the PAI-1 4G/5G polymorphism and pre-eclampsia.

Inherited thrombophilias and pre-eclampsia in Brazilian women

OBJECTIVE

The aim of the present study was to compare the distribution of G1691A, G20210A and C677T mutations in pre-eclamptic Brazilian women and in matched control women with an uncomplicated normal pregnancy.

STUDY DESIGN

these mutations were investigated by PCR-RFLP in 83 normal pregnancies (control group) and in 30 pre-eclamptic pregnant women (severe form).

RESULTS

G1691A mutation was detected neither in the control group nor in pre-eclamsia women. G20210A mutation was detected in heterozygosis in 3 (3.61%) control subjects, but not in pre-eclampsia group. C677T mutation was detected in homozygosis in 6 (7.23%) control subjects and 2 (6.67%) pre-eclamptic women and in heterozygosis in 31 (37.3%) control subjects and 12 (40%) pre-eclamptic women. Differences in the mutation frequencies detected in the two groups were not statistically significant.

CONCLUSION

No correlation was observed between pre-eclampsia and presence of G1691A, G20210A and C677T mutations in Brazilian women.

STOX1 gene in pre-eclampsia and intrauterine growth restriction

The STOX1 gene, identified as a candidate gene for pre-eclampsia in Dutch women, is placentally expressed and subject to imprinting with preferential transmission of the maternal allele. In our study, STOX1-Y153H frequencies were similar in 157 women with pre-eclampsia (65%) and in 157 controls (64%) from the general Dutch population. In an isolated Dutch population, a distortion could not be demonstrated in the transmission of STOX1-Y153H variation from heterozygous mothers to offspring in 50 and 56 families with pregnancies complicated by pre-eclampsia or intrauterine growth restriction, respectively. Our findings do not confirm previous suggestions that STOX1 plays a major role in Dutch women with pre-eclampsia.

Thrombin activatable fibrinolysis inhibitor (TAFI): A role in pre-eclampsia?

Pre-eclampsia (P-Ec) is a complex multisystem disorder of unknown aetiology reported to occur in about 6% to 8% of all pregnancies throughout the world. This disease is associated with fibrin deposition and occlusive lesions in placental vessels. Pro-thrombin activatable fibrinolysis inhibitor (pro-TAFI) is a relatively recently described glycoprotein that can be converted into its active form (TAFIa) by thrombin, thrombin-thrombomodulin and plasmin. TAFIa potentially inhibits fibrinolysis by removing C-terminal lysine and arginine residues from fibrin. These residues are required for adsorption of tissue-type plasminogen activator (t-PA) and plasminogen to fibrin. Therefore, TAFIa decreases plasmin formation and protects the fibrin clot against lysis. An increased of pro-TAFI/TAFIa levels has been reported in some clinical conditions associated with thrombotic tendency, as type II diabetes mellitus, deep vein thrombosis and symptomatic artery disease. Few studies have investigated pro-TAFI/TAFIa in normal or complicated pregnancy but contrasting results were reported. Understanding the role of pro-TAFI/TAFIa in the pathogenesis of P-Ec can hold great promise for improving P-Ec management. In this context, a large-scale study evaluating plasma TAFI antigen and activity, its synthesis and metabolism in pre-eclamptic women is required. Recently new selective TAFIa inhibitors have been developed. The design of a new therapy to treat and/or prevent P-Ec, based on successful use of TAFIa inhibitors, may have significant clinical ramifications.

Relationship between polymorphisms in thrombophilic genes and preeclampsia in a Brazilian population

The purpose of this study was to evaluate the thrombophilic genes in pregnant women with and without preeclampsia independently or in combination. In a prospective case-control study, we investigated four polymorphisms in thrombophilic genes in 75 women with mild or severe preeclampsia and 145 women with normal pregnancy. The genotype frequencies were assessed and the odds ratio (OR) calculated. When we analyzed the polymorphisms independently and the development of preeclampsia, no association was observed [methylenetetrahydrofolate reductase (MTHFR) 677TT genotype, OR 2.07, 95% confidence interval (CI) 0.99-4.30; prothrombin mutation (F II) (GA or AA genotypes) OR 8.11, 95% CI 0.89-73.92; factor V Leiden (FV Leiden) OR 3.94, 95% CI 0.35-44.23; plasminogen activator inhibitor (PAI-1) 4G/4G genotype, OR 1.63, 95% CI 0.87-3.05] not even with severe preeclampsia subgroup analysis. However, when we investigated a possible interaction among these polymorphisms on the development of the preeclampsia, the OR for having one risk genotype, one or two genotype risk factors and two genotype risk factors compared to those without genotype risk factors were 1.97 (95% CI 1.08-3.59), 2.21 (95% CI 1.25-3.92) and 4.27 (95% CI 1.3-13.9), respectively. In conclusion, in the population analyzed, the presence of the genotype risk factors alone does not seem to be associated with the development of preeclampsia even in the severe presentation form. However, an interaction among the MTHFR, F II, FV and PAI-1 gene polymorphisms on the development of the preeclampsia was indicated.

Methylenetetrahydrofolate Reductase Polymorphisms and the Risk of Gestational Hypertension

BACKGROUND

Evidence on the association of 5,10 methylentetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms in women with gestational hypertension is inconsistent. It is also unknown whether the fetal genotype is relevant, or whether folic acid supplementation modifies this association.

METHODS

The study population was composed of U.S. and Canadian white women with nonmalformed infants participating in the Slone Epidemiology Center Birth Defects Study between 1993 and 2000. Women were interviewed within 6 months after delivery regarding multivitamin use in pregnancy and the occurrence of gestational hypertension, among other factors. DNA was extracted from cheek swabs and gene alleles determined by restriction fragment length polymorphism analysis. We compared the prevalence of the 677TT/CT and 1298CC/AC genotypes between cases with gestational hypertension (54 mothers and their 51 offspring) and controls (100 mothers and their 99 offspring). We also estimated odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression to control for geographic region and calendar year.

RESULTS

The T allele was present in 69% of women with gestational hypertension versus 57% of control women (compared with 677CC, OR = 1.9; 95% CI = 0.9-4.0). The offspring of case and control women had a 677TT/CT genotype prevalence of 68% and 47%, respectively (2.4; 1.1-5.0). Among women supplemented with folic acid during the first 5 months of pregnancy, the ORs for maternal and fetal 677TT/CT genotypes were 0.9 (0.3-2.5) and 2.1 (0.7-6.0), respectively. Neither maternal nor fetal 1298CC/AC genotypes were associated with an increased risk of gestational hypertension.

CONCLUSION

Maternal and fetal MTHFR C677T polymorphism may be associated with a moderately increased risk of gestational hypertension, and there is a suggestion that this association may be diminished among women receiving folate supplementation during pregnancy.

Thrombophilia and pregnancy outcomes

Pregnancy complications are still a challenge for physicians, because knowledge of pathomechanisms and prophylactic measures is still limited. In recent years thrombophilia as a risk factor for pregnancy complications has gained much attention in the scientific community. However, data on this topic in the literature are conflicting. Besides an established association between antiphospholipid antibodies and pregnancy loss, available data suggest additional associations for antithrombin deficiency, hyperhomocysteinemia and also for factor (F)V Leiden, prothrombin G20210A variation, and protein S-deficiency. The contribution of thrombophilia to the risk of pre-eclampsia is less well established and recent studies did not confirm earlier data suggesting an association between thrombophilia and pre-eclampsia. A limited number of prospective studies have failed to reveal an increased risk of pregnancy complications in unselected women with thrombosis risk factors. Low-molecular weight heparin (LMWH) seems to have a positive effect on pregnancy outcome after single or recurrent abortions, however, data from only one controlled trial are available. Experience in the prevention of pre-eclampsia by prophylactic heparin is very limited, and in addition, data on pregnancy complications in women with known heritable thrombophilia or a history of thrombosis are inconsistent. These women will usually have a favorable pregnancy outcome referring to the European Prospective Cohort on Thrombophilia Study. In conclusion, thrombophilia screening might be justified in women with pregnancy loss and treatment with LMWH might be considered in those with pregnancy loss and thrombophilia. Further prospective studies and controlled interventional trials are urgently needed.

The G20210A prothrombin-gene mutation and the plasminogen activator inhibitor (PAI-1) 5G/5G genotype are associated with early onset of severe preeclampsia

Hereditary risk determinants of venous thrombosis have been reported to be associated with severe preeclampsia. So far there are no data to support whether these risk determinants are related to the time of onset of severe preeclampsia. We used a case-control design, studying 97 women with severe preeclampsia in previous pregnancies and 277 normal women, to assess hereditary risk factors of venous thrombosis as risk determinants for severe preeclampsia. A case-only design comprising solely the 97 women with a history of preeclampsia was used to evaluate these risk factors as risk determinants for early onset of severe preeclampsia. Using the case-control design, there was no significant risk association of the hereditary risk factors with severe preeclampsia [factor V Leiden, odds ratio (OR) 0.9, 95% confidence interval (CI) 0.4, 2.2; prothrombin mutation, OR 1.9, 95% CI 0.5, 7.0; methylentetrahydrofolate reductase 677TT genotype, OR 0.8, 95% CI 0.4, 1.8; plasminogen activator inhibitor (PAI-1) 4G/4G genotype, OR 1.2, 95% CI 0.7, 2.1; PAI-1 5G/5G genotype, OR 1.0, 95% CI 0.5, 1.8]. However, the onset of severe preeclampsia was significantly earlier in women with the G20210A prothrombin gene mutation (24.5 weeks vs. 30.1 weeks, P = 0.046) and in women with the PAI-1 5G/5G genotype (25.7 weeks vs. 30.8 weeks, P = 0.024). Hereditary risk factors for venous thrombosis do not predispose for severe preeclampsia. However, women who are carriers of the G20210A prothrombin gene mutation and the PAI-1 5G/5G genotype are at risk for early onset of severe preeclampsia. It appears that these risk factors do not induce the pathomechanism but accelerate the course of preeclampsia.