Fetal and maternal contributions to risk of pre-eclampsia: population based study

Preeclampsia does not share common risk alleles in 9p21 with coronary artery disease and type 2 diabetes

INTRODUCTION

Preeclampsia is a common and partially genetic pregnancy complication characterized by hypertension and proteinuria. Association with cardiovascular disease and type 2 diabetes has been reported in 9p21 by several genome-wide association studies. It has been hypothesized that cardiometabolic diseases may share common etiology with preeclampsia.

MATERIALS AND METHODS

We tested association with the 9p21 region to preeclampsia in the Finnish population by genotyping 23 tagging single nucleotide polymorphisms (SNPs) in 15 extended preeclampsia families and in a nationwide cohort consisting of 281 cases and 349 matched controls. Replication was conducted in additional datasets.

RESULTS

Four SNPs (rs7044859, rs496892, rs564398 and rs7865618) showed nominal association (p ≤ 0.024 uncorrected) with preeclampsia in the case-control cohort. To increase power, we genotyped two SNPs in additional 388 cases and 341 controls from the Finnish Genetics of Preeclampsia Consortium (FINNPEC) cohort. Partial replication was also attempted in a UK cohort (237 cases and 199 controls) and in 74 preeclamptic families from Australia/New Zealand. We were unable to replicate the initial association in the extended Finnish dataset or in the two international cohorts.

CONCLUSIONS

Our study did not find evidence for the involvement of the 9p21 region in the risk of preeclampsia. Key Message Chromosome 9p21 is not associated with preeclampsia.

The paternal polymorphism rs5370 in the EDN1 gene decreases the risk of preeclampsia

OBJECTIVE

To evaluate whether the maternal, paternal or the combined maternal/paternal contribution of SNP rs5370 of the EDN1 gene is associated with preeclampsia and drove its expression in placenta.

STUDY DESIGN

This case-control study included 61 preeclamptic patients and their partners and 49 healthy pregnant women and their partners. The population was sub-divided into three groups: women-only, men-only and combined (women/men). The analysis included genotyping of rs5370 in mothers and fathers and evaluating the expression profile of the EDN1 gene in placenta. Comparisons of categorical variables were performed using chi-square and/or Fisher's exact tests. The intergroup comparisons were analysed with the Mann-Whitney U test. The association between the polymorphism and the disease was evaluated through multivariate regression analysis. Spearman's correlation was performed to test the relationship between pre-gestational history and clinical features of the affected patients with EDN1 gene expression.

RESULTS

The analysis of paternal risk factors associated with preeclampsia revealed no differences between groups. A negative association between SNP rs5370 and preeclampsia was found in men group (OR 0.42; CI 95% 0.18-0.94, p=0.034) but not in women or combined groups. The adjustment for paternal protective factors increased the observed negative association, and the opposite was observed in the presence of paternal risk factors. The expression of the EDN1 gene in the placenta was significantly higher in the group of cases and was not associated with the rs5370 polymorphism.

CONCLUSION

The paternal rs5370 polymorphism decreases the risk for preeclampsia and is not associated with placental expression of the EDN1 gene.

Exome sequencing in pooled DNA samples to identify maternal pre-eclampsia risk variants

Pre-eclampsia is a common pregnancy disorder that is a major cause for maternal and perinatal mortality and morbidity. Variants predisposing to pre-eclampsia might be under negative evolutionary selection that is likely to keep their population frequencies low. We exome sequenced samples from a hundred Finnish pre-eclamptic women in pools of ten to screen for low-frequency, large-effect risk variants for pre-eclampsia. After filtering and additional genotyping steps, we selected 28 low-frequency missense, nonsense and splice site variants that were enriched in the pre-eclampsia pools compared to reference data, and genotyped the variants in 1353 pre-eclamptic and 699 non-pre-eclamptic women to test the association of them with pre-eclampsia and quantitative traits relevant for the disease. Genotypes from the SISu project (n = 6118 exome sequenced Finnish samples) were included in the binary trait association analysis as a population reference to increase statistical power. In these analyses, none of the variants tested reached genome-wide significance. In conclusion, the genetic risk for pre-eclampsia is likely complex even in a population isolate like Finland, and larger sample sizes will be necessary to detect risk variants.

Hypertensive disorders of pregnancy: what the physician needs to know

Hypertension developing during pregnancy may be caused by a variety of different pathophysiological mechanisms. The occurrence of proteinuric hypertension during the second half of pregnancy identifies a group of women whose hypertensive disorder is most likely to be caused by the pregnancy itself and for whom the risk of complications, including maternal mortality, is highest. Physicians identifying patients with hypertension in pregnancy need to discriminate between pre-eclampsia and other forms of hypertensive disease. Pre-eclamptic disease requires obstetric intervention before it will resolve and it must be managed in a multidisciplinary environment. The principles of diagnosis and management of these different entities are outlined in this review.

CLTC as a clinically novel gene associated with multiple malformations and developmental delay

Diagnostic exome sequencing has recently emerged as an invaluable tool in determining the molecular etiology of cases involving dysmorphism and developmental delay that are otherwise unexplained by more traditional methods of genetic testing. Our patient was large for gestational age at 35 weeks, delivered to a 27-year-old primigravid Caucasian whose pregnancy was complicated by preeclampsia. Neonatal period was notable for hypoglycemia, apnea, bradycardia, hyperbilirubinemia, grade I intraventricular hemorrhage, subdural hematoma, laryngomalacia, hypotonia, and feeding difficulties. The patient had numerous minor dysmorphic features. At three and a half years of age, she has global developmental delays and nystagmus, and is being followed for a mediastinal neuroblastoma that is currently in remission. Karyotype and oligo-microarray were normal. Whole-exome, next generation sequencing (NGS) coupled to bioinformatic filtering and expert medical review at Ambry Genetics revealed 14 mutations in 9 genes, and these genes underwent medical review. A heterozygous de novo frameshift mutation, c.2737_2738dupGA p.D913Efs*59, in which two nucleotides are duplicated in exon 17 of the CLTC gene, results in substitution of glutamic acid for aspartic acid at position 913 of the protein, as well as a frame shift that results in a premature termination codon situated 58 amino acids downstream. Clathrin Heavy Chain 1 (CHC1) has been shown to play an important role in the brain for vesicle recycling and neurotransmitter release at pre-synaptic nerve terminals. There is also evidence implicating it in the proper development of the placenta during the early stages of pregnancy. The CLTC alteration identified herein is likely to provide an explanation for the patient's adverse phenotype. Ongoing functional studies will further define the impact of this alteration on CHC1 function and consequently, human disease.

Predisposing Factors to Abnormal First Trimester Placentation and the Impact on Fetal Outcomes

Normal placentation during the first trimester sets the stage for the rest of pregnancy and involves a finely orchestrated cellular and molecular interplay of maternal and fetal tissues. The resulting intrauterine environment plays an important role in fetal programming and the future health of the fetus, and is impacted by multiple genetic and epigenetic factors. Abnormalities in placentation and spiral artery invasion can lead to ischemia, placental disease, and adverse obstetrical outcomes including preeclampsia, intrauterine growth restriction, and placental abruption. Although first trimester placentation is affected by multiple factors, preconception environmental influences such as mode of conception, including assisted reproductive technologies which result in fertilization in vitro and intrauterine influences due to sex differences, are emerging as potential significant factors impacting first trimester placentation.

The Norwegian preeclampsia family cohort study: a new resource for investigating genetic aspects and heritability of preeclampsia and related phenotypes

Background

Preeclampsia is a major pregnancy complication without curative treatment available. A Norwegian Preeclampsia Family Cohort was established to provide a new resource for genetic and molecular studies aiming to improve the understanding of the complex pathophysiology of preeclampsia.

Methods

Participants were recruited from five Norwegian hospitals after diagnoses of preeclampsia registered in the Medical birth registry of Norway were verified according to the study’s inclusion criteria. Detailed obstetric information and information on personal and family disease history focusing on cardiovascular health was collected. At attendance anthropometric measurements were registered and blood samples were drawn. The software package SPSS 19.0 for Windows was used to compute descriptive statistics such as mean and SD. P-values were computed based on t-test statistics for normally distributed variables. Nonparametrical methods (chi square) were used for categorical variables.

Results

A cohort consisting of 496 participants (355 females and 141 males) representing 137 families with increased occurrence of preeclampsia has been established, and blood samples are available for 477 participants. Descriptive analyses showed that about 60 % of the index women’s pregnancies with birth data registered were preeclamptic according to modern diagnosis criteria. We also found that about 41 % of the index women experienced more than one preeclamptic pregnancy. In addition, the descriptive analyses confirmed that preeclamptic pregnancies are more often accompanied with delivery complications.

Conclusion

The data and biological samples collected in this Norwegian Preeclampsia Family Cohort will provide an important basis for future research. Identification of preeclampsia susceptibility genes and new biomarkers may contribute to more efficient strategies to identify mothers “at risk” and contribute to development of novel preventative therapies.

The Impact of Multiparity on Uterine Gene Expression and Decidualization in Mice

It has been well established that a previous pregnancy exhibits a beneficial effect on the subsequent pregnancy. However, the underlying mechanisms have not been defined. We hypothesized that multiparity may affect decidualization process during early pregnancy. To test this hypothesis, we analyzed global gene changes associated with multiparity in the mouse uterus using RNA-sequencing (RNA-seq). We identified a total of 131 differentially expressed genes (fold change > 2 and false discovery rate < 0.05), of which 58 were downregulated and 73 genes were upregulated in the second pregnancy (SP) compared to the first pregnancy. Functional clustering analysis showed that genes involved in stress response were significantly enriched. Most importantly, a significant portion of differentially expressed genes, 14 genes or 10.7%, overlapped with the gene list associated with decidualization. Quantitative reverse transcription (RT) polymerase chain reaction (qRT-PCR) analysis confirmed a decreased expression of 4 genes (Klk1, kallikrein 1; H2-Eb1, histocompatibility 2 class II antigen E beta; Mmp7, matrix metallopeptidase 7; Pdpn, podoplanin) and an increase in expression of 2 genes (Thy1, thymus cell antigen 1; Ptgs2, prostaglandin-endoperoxide synthase 2) in SP. Beyond protein-coding genes, we also identified a differentially expressed long noncoding RNA AI506816. Our data provide new insights into the molecular mechanisms underlying the beneficial effect of multiparity.

Fetal Val108/158Met catechol-O-methyltransferase (COMT) polymorphism and placental COMT activity are associated with the development of preeclampsia

OBJECTIVE

To evaluate the association between fetal and maternal catechol-O-methyltransferase (COMT) Val158Met and methyl tetrahydrofolate reductase (MTHFR) C677T functional polymorphisms and preeclampsia, examining its influence on placental COMT and in maternal 2-methoxyestradiol (2-ME) plasma levels.

DESIGN

Prospective case-control study.

SETTING

University hospital.

PATIENT(S)

A total of 53 preeclamptic and 72 normal pregnant women.

INTERVENTION(S)

Maternal and cord blood samples and placental tissue samples were obtained.

MAIN OUTCOME MEASURE(S)

Maternal and fetal COMT and MTHFR polymorphisms were genotyped. Maternal plasma 2-ME and homocysteine levels, and expression and activity of placental COMT were measured.

RESULT(S)

The odds ratio for the risk of preeclampsia for fetal COMT Met/Met was 3.22, and it increased to 8.65 when associated with fetal MTHFR TT. Placental COMT activity and expression were influenced by genotype, but COMT activity in preeclamptic placentas did not differ from control pregnancies. There was no association between any genotypes and maternal 2-ME. Homocysteine levels were higher in women with preeclampsia than in normal pregnancies, and were inversely correlated with 2-ME plasma levels, indicating that its altered metabolism may lower COMT activity in vivo.

CONCLUSION(S)

Fetal Met-Met COMT genotype reduces COMT placental expression and activity in vitro and increases preeclampsia, risk but it does not explain the difference in maternal 2-ME levels between preeclamptic and normal pregnancies. However, the preeclamptic patients had elevated homocysteine levels that correlated inversely with 2-ME, indicating that an altered methionine-homocysteine metabolism may contribute to reduce COMT activity in vivo and explain the decreased levels of 2-ME in preeclamptic women.

Preeclampsia and the Anti-Angiogenic State

Preeclampsia is a major cause of maternal and fetal morbidity and mortality worldwide, however, its etiology remains unclear. Abnormal placental angiogenesis during pregnancy resulting from high levels of anti-angiogenic factors, soluble Flt1 (sFlt1) and soluble endoglin (sEng), has been implicated in preeclampsia pathogenesis. Accumulating evidence also points to a role for these anti-angiogenic proteins as serum biomarkers for the clinical diagnosis and prediction of preeclampsia. Uncovering the mechanisms of altered angiogenic factors in preeclampsia may also provide insights into novel preventive and therapeutic options.

Obstetric and neonatal outcome of pregnancies fathered by males on immunosuppression after solid organ transplantation

Immunosuppressive drugs may influence spermatogenesis, but little is known about outcome of pregnancies fathered by transplanted males. We estimated risk of adverse outcomes in pregnancies (with data after the first trimester) fathered by males that had undergone organ transplantation and were treated with immunosuppression. A population-based study, linking data from the Norwegian transplant registry and the Medical Birth Registry of Norway during 1967-2009 was designed. All Norwegian men undergoing solid organ transplantation were included. Odds ratios for major malformations, preeclampsia, preterm delivery (<37 weeks) and small-for-gestational-age were obtained using logistic regression. A total of 2463 transplanted males, fathering babies of 4614 deliveries before and 474 deliveries after transplantation were identified. The risk of preeclampsia was increased (AOR: 7.4, 95% CI: 1.1-51.4,) after transplantation compared to prior to transplantation. No increased risk was found for congenital malformations or other outcomes when compared with pregnancies before transplantation or with the general population (2 511 506 births). Our results indicate an increased risk of preeclampsia mediated through the transplanted and immunosuppressed father. Importantly, no increased risk was found for other adverse obstetric outcomes or malformations, which may reassure male transplant recipients planning to father children.

Associations of blood pressure in pregnancy with offspring blood pressure trajectories during childhood and adolescence: findings from a prospective study

Background

Hypertensive disorders of pregnancy are related to higher offspring blood pressure (BP), but it is not known whether this association strengthens or weakens as BP changes across childhood. Our aim was to assess the associations of hypertensive disorders of pregnancy and maternal BP changes during pregnancy with trajectories of offspring BP from age 7 to 18 years.

Methods and Results

In a large UK cohort of maternal–offspring pairs (N=6619), we used routine antenatal BP measurements to derive hypertensive disorders of pregnancy and maternal BP trajectories. These were related to offspring BP trajectories, obtained from research clinic assessments, using linear spline random-effects models. After adjusting for maternal and offspring variables, including body mass index, offspring of women who had existing hypertension, gestational hypertension, or preeclampsia during pregnancy had on average higher BP at age 7 years compared to offspring of normotensive pregnancies (mean difference [95%CI] in systolic BP: 1.67 mm Hg [0.48, 2.86], 1.98 mm Hg [1.32, 2.65], and 1.22 mm Hg [−0.52, 2.97], respectively). These differences were consistent across childhood to age 18 years, as the patterns of BP change did not differ between offspring of hypertensive pregnancies and normotensive pregnancies. Maternal BP at 8 weeks’ gestation was also positively associated with offspring BP in childhood and adolescence, but changes in BP across pregnancy were not strongly associated.

Conclusions

The differences in BP between offspring of hypertensive pregnancies and offspring of normotensive pregnancies remain consistent across childhood and adolescence. These associations appear to be most contributed to by higher maternal BP in early pregnancy rather than by pregnancy-related BP changes.

Pre-eclampsia has an adverse impact on maternal and fetal health

Pre-eclampsia (preE) is a multifaceted complication found uniquely in the pregnant patient and one that has puzzled scientists for years. PreE is not a single disorder, but a complex syndrome that is produced by various pathophysiological triggers and mechanisms affecting about 5% of obstetrical patients. PreE is a major cause of premature delivery and maternal and fetal morbidity and mortality. PreE is characterized by de novo development of hypertension and proteinuria after 20 weeks of gestation and affects nearly every organ system, with the most severe consequences being eclampsia, pulmonary edema, intrauterine growth restriction, and thrombocytopenia. PreE alters the intrauterine environment by modulating the pattern of hormonal signals and activating the detrimental cellular signaling that has been transported to the fetus. The fetus has to adapt to this intrauterine environment with detrimental signals. The adaptive changes increase the risk of disease later in life. This review defines the predisposition and causes of preE and the cellular signaling detrimental to maternal health during preE. Moreover, the risk factors for diseases that are transmitted to the offspring have been addressed in this review. The detrimental signaling molecules that have been overexpressed in preE patients raises the possibility that those signals could be therapeutically blocked one day.

Risk factors and effective management of preeclampsia

Preeclampsia, a hypertensive disorder of pregnancy is estimated to complicate 2%–8% of pregnancies and remains a principal cause of maternal and fetal morbidity and mortality. Preeclampsia may present at any gestation but is more commonly encountered in the third trimester. Multiple risk factors have been documented, including: family history, nulliparity, egg donation, diabetes, and obesity. Significant progress has been made in developing tests to predict risk of preeclampsia in pregnancy, but these remain confined to clinical trial settings and center around measuring angiogenic profiles, including placental growth factor or newer tests involving metabolomics. Less progress has been made in developing new treatments and therapeutic targets, and aspirin remains one of the few agents shown to consistently reduce the risk of developing preeclampsia. This review serves to discuss recent advances in risk factor identification, prediction techniques, and management of preeclampsia in antenatal, intrapartum, and postnatal patients.

Prior cesarean section is associated with increased preeclampsia risk in a subsequent pregnancy

Background

To evaluate the impact of a prior cesarean section on preeclampsia risk in a subsequent pregnancy.

Methods

Study data were collected from the Korea National Health Insurance Claims Database of the Health Insurance Review and Assessment Service for 2006–2010. Patients who had their first delivery in 2006 and subsequent delivery between 2007 and 2010 in Korea were enrolled. The overall incidence of preeclampsia during the second pregnancy was estimated and to evaluate the risk of preeclampsia in the second pregnancy, a model of multivariate logistic regression analysis was performed with preeclampsia as the final outcome

Results

The risk of preeclampsia in any pregnancy was 2.17%; the risk in the first pregnancy was 2.76%, and that in the second pregnancy was 1.15%. During the second pregnancy, the risk of preeclampsia was 13.30% for women who had developed preeclampsia in their first pregnancy and 0.85% for those who had not. In the entire population, prior cesarean section was associated with preeclampsia risk in their subsequent pregnancy (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.13–1.41). Among women with and without preeclampsia in their first pregnancy, a prior cesarean section was associated with preeclampsia risk in their second pregnancy (OR, 1.35; 95% CI, 1.09–1.67; OR, 1.23; 95% CI, 1.08–1.40, respectively).

Conclusions

Our study showed that cesarean section in a first pregnancy was associated with increased preeclampsia risk in the second pregnancy. These results provide physicians with a preeclampsia risk evaluation method for a second pregnancy that they may aid counseling in patients.

Association between maternal micronutrient status, oxidative stress, and common genetic variants in antioxidant enzymes at 15 weeks׳ gestation in nulliparous women who subsequently develop preeclampsia

Preeclampsia is a pregnancy-specific condition affecting 2-7% of women and a leading cause of perinatal and maternal morbidity and mortality. Deficiencies of specific micronutrient antioxidant activities associated with copper, selenium, zinc, and manganese have previously been linked to preeclampsia at the time of disease. Our aims were to investigate whether maternal plasma micronutrient concentrations and related antioxidant enzyme activities are altered before preeclampsia onset and to examine the dependence on genetic variations in these antioxidant enzymes. Predisease plasma samples (15±1 weeks׳ gestation) were obtained from women enrolled in the international Screening for Pregnancy Endpoints (SCOPE) study who subsequently developed preeclampsia (n=244) and from age- and BMI-matched normotensive controls (n=472). Micronutrient concentrations were measured by inductively coupled plasma mass spectrometry; associated antioxidant enzyme activities, selenoprotein-P, ceruloplasmin concentration and activity, antioxidant capacity, and markers of oxidative stress were measured by colorimetric assays. Sixty-four tag-single-nucleotide polymorphisms (SNPs) within genes encoding the antioxidant enzymes and selenoprotein-P were genotyped using allele-specific competitive PCR. Plasma copper and ceruloplasmin concentrations were modestly but significantly elevated in women who subsequently developed preeclampsia (both P<0.001) compared to controls (median (IQR), copper, 1957.4 (1787, 2177.5) vs 1850.0 (1663.5, 2051.5) µg/L; ceruloplasmin, 2.5 (1.4, 3.2) vs 2.2 (1.2, 3.0) µg/ml). There were no differences in other micronutrients or enzymes between groups. No relationship was observed between genotype for SNPs and antioxidant enzyme activity. This analysis of a prospective cohort study reports maternal micronutrient concentrations in combination with associated antioxidant enzymes and SNPs in their encoding genes in women at 15 weeks׳ gestation that subsequently developed preeclampsia. The modest elevation in copper may contribute to oxidative stress, later in pregnancy, in those women that go on to develop preeclampsia. The lack of evidence to support the hypothesis that functional SNPs influence antioxidant enzyme activity in pregnant women argues against a role for these genes in the etiology of preeclampsia.

InterPregGen: genetic studies of pre-eclampsia in three continents

Pre-eclampsia is a major cause of maternal and fetal mortality in pregnancy. The identification of genetic variants which predispose to pre-eclampsia demands large DNA collections from affected mothers and babies and controls, with reliable supporting phenotypic data. The InterPregGen study has assembled a consortium of researchers from Europe, Central Asia and South America with the aim of elucidating the genetic architecture of pre-eclampsia. The MoBa collection is playing a vital role in this collaborative venture, which has the potential to provide new insights into the causes of pre-eclampsia, and provide a rational basis for novel approaches to prevention and treatment.

Antepartum dalteparin versus no antepartum dalteparin for the prevention of pregnancy complications in pregnant women with thrombophilia (TIPPS): a multinational open-label randomised trial

BACKGROUND

Thrombophilias are common disorders that increase the risk of pregnancy-associated venous thromboembolism and pregnancy loss and can also increase the risk of placenta-mediated pregnancy complications (severe pre-eclampsia, small-for-gestational-age infants, and placental abruption). We postulated that antepartum dalteparin would reduce these complications in pregnant women with thrombophilia.

METHODS

In this open-label randomised trial undertaken in 36 tertiary care centres in five countries, we enrolled consenting pregnant women with thrombophilia at increased risk of venous thromboembolism or with previous placenta-mediated pregnancy complications. Eligible participants were randomly allocated in a 1:1 ratio to either antepartum prophylactic dose dalteparin (5000 international units once daily up to 20 weeks' gestation, and twice daily thereafter until at least 37 weeks' gestation) or to no antepartum dalteparin (control group). Randomisation was done by a web-based randomisation system, and was stratified by country and gestational age at randomisation day with a permuted block design (block sizes 4 and 8). At randomisation, site pharmacists (or delegates) received a randomisation number and treatment allocation (by fax and/or e-mail) from the central web randomisation system and then dispensed study drug to the local coordinator. Patients and study personnel were not masked to treatment assignment, but the outcome adjudicators were masked. The primary composite outcome was independently adjudicated severe or early-onset pre-eclampsia, small-for-gestational-age infant (birthweight <10th percentile), pregnancy loss, or venous thromboembolism. We did intention-to-treat and on-treatment analyses. This trial is registered with ClinicalTrials.gov, number NCT00967382, and with Current Controlled Trials, number ISRCTN87441504.

FINDINGS

Between Feb 28, 2000, and Sept 14, 2012, 292 women consented to participate and were randomly assigned to the two groups. Three women were excluded after randomisation because of ineligibility (two in the antepartum dalteparin group and one in the control group), leaving 146 women assigned to antepartum dalteparin and 143 assigned to no antepartum dalteparin. Some patients crossed over to the other group during treatment, and therefore for on-treatment and safety analysis there were 143 patients in the dalteparin group and 141 in the no dalteparin group. Dalteparin did not reduce the incidence of the primary composite outcome in both intention-to-treat analysis (dalteparin 25/146 [17·1%; 95% CI 11·4-24·2%] vs no dalteparin 27/143 [18·9%; 95% CI 12·8-26·3%]; risk difference -1·8% [95% CI -10·6% to 7·1%)) and on-treatment analysis (dalteparin 28/143 [19·6%] vs no dalteparin 24/141 [17·0%]; risk difference +2·6% [95% CI -6·4 to 11·6%]). In safety analysis, the occurrence of major bleeding did not differ between the two groups. However, minor bleeding was more common in the dalteparin group (28/143 [19·6%]) than in the no dalteparin group (13/141 [9·2%]; risk difference 10·4%, 95% CI 2·3-18·4; p=0·01).

INTERPRETATION

Antepartum prophylactic dalteparin does not reduce the occurrence of venous thromboembolism, pregnancy loss, or placenta-mediated pregnancy complications in pregnant women with thrombophilia at high risk of these complications and is associated with an increased risk of minor bleeding.

FUNDING

Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, and Pharmacia and UpJohn.

Validity of pre-eclampsia registration in the medical birth registry of norway for women participating in the norwegian mother and child cohort study, 1999-2010

BACKGROUND

The Norwegian Mother and Child Cohort Study (MoBa), a prospective population-based pregnancy cohort, is a valuable database for studying causes of pre-eclampsia. Pre-eclampsia data in MoBa come from the Medical Birth Registry of Norway (MBRN); thus, we wanted to study the validity of MBRN pre-eclampsia registration for MoBa women.

METHODS

We selected all MoBa pregnancies with pre-eclampsia registered in the MBRN (n = 4081) and a random control group (n = 2000) without pre-eclampsia registrations. After excluding two delivery units not participating in MoBa and one no longer operating, units were asked to provide copies of antenatal charts with blood pressure and urinary measurements from all antenatal visits during pregnancy, and hospital discharge codes from the delivery stay. We received data for 5340 pregnancies delivered 1999-2010 (87% of all eligible). We calculated positive predictive value (PPV), and sensitivity and specificity of MBRN registration, using hypertension and proteinuria on the antenatal charts and/or hospital discharge codes indicating pre-eclampsia as gold standard.

RESULTS

Overall PPV was 83.9% [95% CI 82.7, 85.1] and was higher when women were primiparous, or delivered preterm or low birthweight infants. Severe pre-eclampsia in the MBRN was found to be a true severe pre-eclampsia in 70% of cases. Extrapolating to the total MoBa population, the estimated sensitivity was low - 43.0% (38.7, 48.2) - while specificity was high - 99.2% (99.2, 99.3). False negative cases seemed to have mild forms of pre-eclampsia.

CONCLUSIONS

PPV and specificity of pre-eclampsia registration in the MBRN during 1999-2010 was satisfactory, while sensitivity was low.

Genetic contribution to postpartum haemorrhage in Swedish population: cohort study of 466,686 births

OBJECTIVE

To investigate the familial clustering of postpartum haemorrhage in the Swedish population, and to quantify the relative contributions of genetic and environmental effects.

DESIGN

Register based cohort study.

SETTING

Swedish population (multi-generation and medical birth registers).

MAIN OUTCOME MEASURE

Postpartum haemorrhage, defined as >1000 mL estimated blood loss.

PARTICIPANTS

The first two live births to individuals in Sweden in 1997-2009 contributed to clusters representing intact couples (n = 366,350 births), mothers with separate partners (n = 53,292), fathers with separate partners (n = 47,054), sister pairs (n = 97,228), brother pairs (n = 91,168), and mixed sibling pairs (n = 177,944).

METHODS

Familial clustering was quantified through cluster specific tetrachoric correlation coefficients, and the influence of potential sharing of known risk factors was evaluated with alternating logistic regression. Relative contributions of genetic and environmental effects to the variation in liability for postpartum haemorrhage were quantified with generalised linear mixed models.

RESULTS

The overall prevalence of postpartum haemorrhage after vaginal deliveries in our sample was 4.6%. Among vaginal deliveries, 18% (95% confidence interval 9% to 26%) of the variation in postpartum haemorrhage liability was attributed to maternal genetic factors, 10% (1% to 19%) to unique maternal environment, and 11% (0% to 26%) to fetal genetic effects. Adjustment for known risk factors only partially explained estimates of familial clustering, suggesting that the observed shared genetic and environmental effects operate in part through pathways independent of known risk factors. There were similar patterns of familial clustering for both of the main subtypes examined (atony and retained placenta), though strongest for haemorrhage after retained placenta.

CONCLUSIONS

There is a maternal genetic predisposition to postpartum haemorrhage, but more than half of the total variation in liability is attributable to factors that are not shared in families.

Pre-eclampsia part 1: current understanding of its pathophysiology

Pre-eclampsia is characterized by new-onset hypertension and proteinuria at ≥20 weeks of gestation. In the absence of proteinuria, hypertension together with evidence of systemic disease (such as thrombocytopenia or elevated levels of liver transaminases) is required for diagnosis. This multisystemic disorder targets several organs, including the kidneys, liver and brain, and is a leading cause of maternal and perinatal morbidity and mortality. Glomeruloendotheliosis is considered to be a characteristic lesion of pre-eclampsia, but can also occur in healthy pregnant women. The placenta has an essential role in development of this disorder. Pathogenetic mechanisms implicated in pre-eclampsia include defective deep placentation, oxidative and endoplasmic reticulum stress, autoantibodies to type-1 angiotensin II receptor, platelet and thrombin activation, intravascular inflammation, endothelial dysfunction and the presence of an antiangiogenic state, among which an imbalance of angiogenesis has emerged as one of the most important factors. However, this imbalance is not specific to pre-eclampsia, as it also occurs in intrauterine growth restriction, fetal death, spontaneous preterm labour and maternal floor infarction (massive perivillous fibrin deposition). The severity and timing of the angiogenic imbalance, together with maternal susceptibility, might determine the clinical presentation of pre-eclampsia. This Review discusses the diagnosis, classification, clinical manifestations and putative pathogenetic mechanisms of pre-eclampsia.

Bioinformatic approach to the genetics of preeclampsia

OBJECTIVE

To identify candidate genes and genetic variants for preeclampsia using a bioinformatic approach to extract and organize genes and variants from the published literature.

METHODS

Semantic data-mining and natural language processing were used to identify articles from the published literature meeting criteria for potential association with preeclampsia. Articles were manually reviewed by trained curators. Cluster analysis was used to aggregate the extracted genes into gene sets associated with preeclampsia or severe preeclampsia, early or late preeclampsia, maternal or fetal tissue sources, and concurrent conditions (ie, fetal growth restriction, gestational hypertension, or hemolysis, elevated liver enzymes, and low platelet count [HELLP]). Gene ontology was used to organize this large group of genes into ontology groups.

RESULTS

From more than 22 million records in PubMed, with 28,000 articles on preeclampsia, our data-mining tool identified 2,300 articles with potential genetic associations with preeclampsia-related phenotypes. After curation, 729 articles were "accepted" that contained "statistically significant" associations with 535 genes. We saw distinct segregation of these genes by severity and timing of preeclampsia, by maternal or fetal source, and with associated conditions (eg, gestational hypertension, fetal growth restriction, or HELLP syndrome).

CONCLUSION

The gene sets and ontology groups identified through our systematic literature curation indicate that preeclampsia represents several distinct phenotypes with distinct and overlapping maternal and fetal genetic contributions.

LEVEL OF EVIDENCE

III.

Genetic aspects of preeclampsia and the HELLP syndrome

Both preeclampsia and the HELLP syndrome have their origin in the placenta. The aim of this study is to review genetic factors involved in development of preeclampsia and the HELLP syndrome using literature search in PubMed. A familial cohort links chromosomes 2q, 5q, and 13q to preeclampsia. The chromosome 12q is coupled with the HELLP syndrome. The STOX1 gene, the ERAP1 and 2 genes, the syncytin envelope gene, and the −670 Fas receptor polymorphisms are involved in the development of preeclampsia. The ACVR2A gene on chromosome 2q22 is also implicated. The toll-like receptor-4 (TLR-4) and factor V Leiden mutation participate both in development of preeclampsia and the HELLP syndrome. Carriers of the TT and the CC genotype of the MTHFR C677T polymorphism seem to have an increased risk of the HELLP syndrome. The placental levels of VEGF mRNA are reduced both in women with preeclampsia and in women with the HELLP syndrome. The BclI polymorphism is engaged in development of the HELLP syndrome but not in development of severe preeclampsia. The ACE I/D polymorphism affects uteroplacental and umbilical artery blood flows in women with preeclampsia. In women with preeclampsia and the HELLP syndrome several genes in the placenta are deregulated. Preeclampsia and the HELLP syndrome are multiplex genetic diseases.

Pregnancy, parturition and preeclampsia in women of African ancestry

Maternal and associated neonatal mortality rates in sub-Saharan Africa remain unacceptably high. In Mulago Hospital (Kampala, Uganda), 2 major causes of maternal death are preeclampsia and obstructed labor and their complications, conditions occurring at the extremes of the birthweight spectrum, a situation encapsulated as the obstetric dilemma. We have questioned whether the prevalence of these disorders occurs more frequently in indigenous African women and those with African ancestry elsewhere in the world by reviewing available literature. We conclude that these women are at greater risk of preeclampsia than other racial groups. At least part of this susceptibility seems independent of socioeconomic status and likely is due to biological or genetic factors. Evidence for a genetic contribution to preeclampsia is discussed. We go on to propose that the obstetric dilemma in humans is responsible for this situation and discuss how parturition and birthweight are subject to stabilizing selection. Other data we present also suggest that there are particularly strong evolutionary selective pressures operating during pregnancy and delivery in Africans. There is much greater genetic diversity and less linkage disequilibrium in Africa, and the genes responsible for regulating birthweight and placentation may therefore be easier to define than in non-African cohorts. Inclusion of African women into research on preeclampsia is an essential component in tackling this major disparity of maternal health.

Early onset preeclampsia in subsequent pregnancies correlates with early onset preeclampsia in first pregnancy

OBJECTIVE

Preeclampsia is a major complication of pregnancy and its occurrence in a first pregnancy is a major risk factor for recurrence in subsequent pregnancies. Whether the time of onset or the severity of preeclampsia in a first pregnancy is associated with the incidence of recurrent preeclampsia is not clear. We performed a retrospective study to analyse the incidence of recurrent preeclampsia and associations of the time of onset and the severity of preeclampsia between first preeclampsia and recurrent preeclampsia.

STUDY DESIGN

Ninety-two women with previous preeclampsia who had a second pregnancy in a 4 year period were included. Data on the first and second pregnancies were obtained and included maternal age, maternal height and weight, gestation week at onset of preeclampsia and at delivery, blood pressure, proteinuria, interval between pregnancies and birth weights.

RESULTS

Fifty-five women with previous preeclampsia developed recurrent preeclampsia (59.8%). The difference in the incidence of recurrent early and late onset preeclampsia was not significant different (65.3% versus 53.4%, p>0.05). The difference in the incidence of mild or severe disease in those who experienced recurrent preeclampsia was also not significant (59.6% versus 60%, p>0.05). The severity of preeclampsia in second pregnancy was not associated with the severity of preeclampsia in first pregnancy. However 93.7% women with previous early onset preeclampsia developed early onset preeclampsia in second pregnancy and 56.5% women with previous late onset preeclampsia developed early onset preeclampsia in second pregnancy. In addition, 76.2% women with previous mild preeclampsia developed severe preeclampsia in second pregnancy. The baby weight in recurrent preeclampsia was significantly decreased compared to that in first pregnancy with preeclampsia.

CONCLUSION

Our data demonstrate that there was no association between the incidence of recurrent preeclampsia and the time of onset or severity of preeclampsia in first pregnancy. But our data here may suggest that women with early onset preeclampsia in first pregnancy are more likely to experience early onset preeclampsia in second pregnancy. The severity of recurrent preeclampsia is increased regardless the severity in first pregnancy.

Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy

OBJECTIVE

This guideline summarizes the quality of the evidence to date and provides a reasonable approach to the diagnosis, evaluation and treatment of the hypertensive disorders of pregnancy (HDP).

EVIDENCE

The literature reviewed included the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) HDP guidelines from 2008 and their reference lists, and an update from 2006. Medline, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Registry of Controlled Trials (CCRCT) and Database of Abstracts and Reviews of Effects (DARE) were searched for literature published between January 2006 and March 2012. Articles were restricted to those published in French or English. Recommendations were evaluated using the criteria of the Canadian Task Force on Preventive Health Care and GRADE.

Risk for Recurrence of Pre-eclampsia in the Subsequent Pregnancy

BACKGROUND

Pre-eclampsia (PE) is the commonest type of pregnancy induced hypertension and it affects nearly 5% of pregnant women. Besides short term morbidity and mortality that are associated with pregnancy, PE is associated with long term morbidity in women. There is a lack of information on the risk of recurrence of PE in pregnant Asian Indian women.

AIM

To determine the rates and risk factors which were associated with recurrence of PE in the subsequent pregnancies of women with PE in index pregnancies.

SETTINGS AND DESIGN

A retrospective, observational study done at a single tertiary care centre in southern India.

MATERIAL AND METHODS

The study included pregnant women with PE, who delivered at the study institute in 2008 and received care for their subsequent pregnancies at the study institute. Hypertension in pregnancy was categorized, based on the criteria of the International Society for the Study of Hypertension in Pregnancy. Point estimates and the 95% confidence intervals around point estimates of rates of recurrence of PE and associations of potential clinical and laboratory parameters with recurrence were determined by using bivariate analysis, logistic regression models and area under Receiver Operator Characteristic (ROC) curves.

RESULTS

The study included 82 pregnant women with PE in their index pregnancies. Twenty two (26.83%, 95% CI: 17.03, 36.62) of these 82 women developed recurrence of PE in their subsequent pregnancies. Recurrence of PE was significantly higher (OR 3.94, 95% CI: 1.05, 14.80, p=0.04) among women who were nulliparous in their index pregnancies. Recurrence of PE was not significantly associated with clinical factors or laboratory parameters in the index pregnancies.

CONCLUSION

Nearly one in four of pregnant women with PE developed recurrences in their subsequent pregnancies, although a large proportion of pregnant women with PE (63.38% to 82.97%) in their index pregnancies were normotensive in their subsequent pregnancies.

Interbirth interval and history of previous preeclampsia: a case-control study among multiparous women

Background

Preeclampsia is a disorder with a reported incidence of 2%-8% among all pregnancies, accounting for more than 50,000 deaths worldwide each year. In low- and middle- income countries maternal/perinatal morbidity and mortality associated with preeclampsia are high due to the lack of proper prenatal and hospital care and limited access to neonatal intensive care. The objectives of our study were to determine the association of long interbirth interval (IBI) and preeclampsia and to investigate the interactions between long IBI and other risk factors among multiparous women in Yerevan, Armenia.

Methods

We conducted a hospital-based case–control study among 36 multiparous women with preeclampsia (cases) and 148 without preeclampsia (controls) during their last pregnancy, selected from the two largest maternity hospitals in Armenia. The data were collected through telephone-based structured interviews and analyzed using STATA software. The study applied univariate and multivariate logistic regression analyses.

Results

The study found a significant interaction between IBI and previous history of preeclampsia. Among women without a history of previous preeclampsia, the odds of having preeclampsia among women with long IBI (greater than or equal to five years) was 6.88 time higher compared to those with short IBI (CI: 1.75-27.05; p = 0.006) after adjusting for confounders; among women with a history of previous preeclampsia the odds ratio was 0.60 (CI: 0.07-4.99; p = 0.638). The final fitted model for preeclampsia among multiparous women who had planned their pregnancies included IBI, time to pregnancy, Body Mass Index, method of contraception and household monthly income.

Conclusions

Long IBI appeared to be a strong risk factor for preeclampsia development only among women without a history of previous preeclampsia. This finding may contribute to a new approach in understanding the etiology of preeclampsia and may be useful for developing further recommendations for this particular subgroup of women that are at higher risk for preeclampsia development in subsequent pregnancies.

Associations of personal and family preeclampsia history with the risk of early-, intermediate- and late-onset preeclampsia

Preeclampsia encompasses multiple conditions of varying severity. We examined the recurrence and familial aggregation of preeclampsia by timing of onset, which is a marker for severity. We ascertained personal and family histories of preeclampsia for women who delivered live singletons in Denmark in 1978-2008 (almost 1.4 million pregnancies). Using log-linear binomial regression, we estimated risk ratios for the associations between personal and family histories of preeclampsia and the risk of early-onset (before 34 weeks of gestation, which is typically the most severe), intermediate-onset (at 34-36 weeks of gestation), and late-onset (after 36 weeks of gestation) preeclampsia. Previous early-, intermediate-, or late-onset preeclampsia increased the risk of recurrent preeclampsia with the same timing of onset 25.2 times (95% confidence interval (CI): 21.8, 29.1), 19.7 times (95% CI: 17.0, 22.8), and 10.3 times (95% CI: 9.85, 10.9), respectively, compared with having no such history. Preeclampsia in a woman's family was associated with a 24%-163% increase in preeclampsia risk, with the strongest associations for early- and intermediate-onset preeclampsia in female relatives. Preeclampsia in the man's family did not affect a woman's risk of early-onset preeclampsia and was only weakly associated with her risks of intermediate- and late-onset preeclampsia. Early-onset preeclampsia appears to have the largest genetic component, whereas environmental factors likely contribute most to late-onset preeclampsia. The role of paternal genes in the etiology of preeclampsia appears to be limited.

Increased decidual mRNA expression levels of candidate maternal pre-eclampsia susceptibility genes are associated with clinical severity

INTRODUCTION

Pre-eclampsia (PE) has a familial association, with daughters of women who had PE during pregnancy having more than twice the risk of developing PE themselves. Through genome-wide linkage and genetic association studies in PE-affected families and large population samples, we previously identified the following as positional candidate maternal susceptibility genes for PE; ACVR1, INHA, INHBB, ERAP1, ERAP2, LNPEP, COL4A1 and COL4A2. The aims of this study were to determine mRNA expression levels of previously identified candidate maternal pre-eclampsia susceptibility genes from normotensive and severe PE (SPE) pregnancies and correlate mRNA expression levels with the clinical severity of SPE.

METHODS

Third trimester decidual tissues were collected from both normotensive (n = 21) and SPE pregnancies (n = 24) and mRNA expression levels were determined by real-time PCR. Gene expression was then correlated with several parameters of clinical severity in SPE. Statistical significance was determined by Mann-Whitney U test and Spearman's Correlation.

RESULTS

The data demonstrate significantly increased decidual mRNA expression levels of ACVR1, INHBB, ERAP1, ERAP2, LNPEP, COL4A1 and COL4A2 in SPE (p < 0.05). Increased mRNA expression levels of several genes - INHA, INHBB, COL4A1 and COL4A2 were correlated with earlier onset of PE and earlier delivery of the fetus (p < 0.05).

CONCLUSION

These results suggest altered expression of maternal susceptibility genes may play roles in PE development and the course of disease severity.

Recurrence of preeclampsia in northern Tanzania: a registry-based cohort study

OBJECTIVE

Preeclampsia occurs in about 4 per cent of pregnancies worldwide, and may have particularly serious consequences for women in Africa. Studies in western countries have shown that women with preeclampsia in one pregnancy have a substantially increased risk of preeclampsia in subsequent pregnancies. We estimate the recurrence risks of preeclampsia in data from Northern Tanzania.

METHODS

A prospective cohort study was designed using 19,811 women who delivered singleton infants at a hospital in Northern Tanzania between 2000 and 2008. A total of 3,909 women were recorded with subsequent deliveries in the hospital with follow up through 2010. Adjusted recurrence risks of preeclampsia were computed using regression models.

RESULTS

The absolute recurrence risk of preeclampsia was 25%, which was 9.2-fold (95% CI: 6.4 - 13.2) compared with the risk for women without prior preeclampsia. When there were signs that the preeclampsia in a previous pregnancy had been serious either because the baby was delivered preterm or had died in the perinatal period, the recurrence risk of preeclampsia was even higher. Women who had preeclampsia had increased risk of a series of adverse pregnancy outcomes in future pregnancies. These include perinatal death (RR= 4.3), a baby with low birth weight (RR= 3.5), or a preterm birth (RR= 2.5). These risks were only partly explained by recurrence of preeclampsia.

CONCLUSIONS

Preeclampsia in one pregnancy is a strong predictor for preeclampsia and other adverse pregnancy outcomes in subsequent pregnancies in Tanzania. Women with previous preeclampsia may benefit from close follow-up during their pregnancies.

Contribution of fetal ANXA5 gene promoter polymorphisms to the onset of pre-eclampsia

OBJECTIVE

A common haplotype M2 consisting of minor SNP alleles located in the ANXA5 gene promoter region has been described as a risk factor for various obstetric complications such as recurrent pregnancy loss, pre-eclampsia and pregnancy-related thrombophilic disorder. However, the question of whether it is the maternal or fetal genotype that contributes to the onset of these disorders remains to be resolved.

METHODS

We analyzed ANXA5 gene variants in the blood and placental tissues from pre-eclampsia patients and normotensive controls. ANXA5 expression was examined by qRT-PCR, Western blotting and immunostaining. Results were compared between M2 and non-M2 carriers.

RESULTS

The M2 haplotype was found to be significantly frequent in placentas from pre-eclamptic patients relative to the controls (25.5% versus 10%, P = 0.044), In contrast, no significant differences were observed in maternal blood (13.0% versus 11.3%, P = 0.597). The placental expression of ANXA5 mRNA was found to be lower in M2 carriers. When examined by Western blot and immunostaining, the ANXA5 protein levels were found to be affected more by the placental than the maternal genotype. Histological examination of the placentas from the pre-eclamptic patients demonstrated that a placental M2 haplotype correlated more closely than maternal M2 with the severity of perivillous fibrin deposition.

CONCLUSIONS

Although preliminary, these results suggest that hypomorphic M2 alleles in the in placental ANXA5 promoter, whether transmitted maternally or paternally, might be an essential determinant of an increased risk of pre-eclampsia via local thrombophilia at the feto-maternal interface.

Two variants of the C-reactive protein gene are associated with risk of pre-eclampsia in an American Indian population

BACKGROUND

The etiology of pre-eclampsia (PE) is unknown; but it is accepted that normal pregnancy represents a distinctive challenge to the maternal immune system. C-reactive protein is a prominent component of the innate immune system; and we previously reported an association between PE and the CRP polymorphism, rs1205. Our aim was to explore the effects of additional CRP variants. The IBC (Cardiochip) genotyping microarray focuses on candidate genes and pathways related to the pathophysiology of cardiovascular disease.

METHODS

This study recruited 140 cases of PE and 270 matched controls, of which 95 cases met criteria as severe PE, from an American Indian community. IBC array genotypes from 10 suitable CRP SNPs were analyzed. A replication sample of 178 cases and 427 controls of European ancestry was also genotyped.

RESULTS

A nominally significant difference (p value <0.05) was seen in the distribution of discordant matched pairs for rs3093068; and Bonferroni corrected differences (P<0.005) were seen for rs876538, rs2794521, and rs3091244. Univariate conditional logistic regression odds ratios (OR) were nominally significant for rs3093068 and rs876538 models only. Multivariate logistic models with adjustment for mother's age, nulliparity and BMI attenuated the effect (OR 1.58, P = 0.066, 95% CI 0.97-2.58) for rs876538 and (OR 2.59, P = 0.050, 95% CI 1.00-6.68) for rs3093068. An additive risk score of the above two risk genotypes shows a multivariate adjusted OR of 2.04 (P = 0.013, 95% CI 1.16-3.56). The replication sample also demonstrated significant association between PE and the rs876538 allele (OR = 1.55, P = 0.01, 95% CI 2.16-1.10). We also show putative functionality for the rs876538 and rs3093068 CRP variants.

CONCLUSION

The CRP variants, rs876538 and rs3093068, previously associated with other cardiovascular disease phenotypes, show suggestive association with PE in this American Indian population, further supporting a possible role for CRP in PE.

Preeclampsia: an obstetrician's perspective

Preeclampsia is a pregnancy-specific syndrome that usually develops after 20 weeks gestation. The exact pathogenic mechanisms remain uncertain and are likely multifactorial. Preeclampsia is a heterogeneous condition with potentially maternal and fetal consequences. As part of the spectrum of hypertensive disorders of pregnancy, preeclampsia may progress rapidly and is a leading cause of maternal and perinatal morbidity and mortality worldwide. In the United States, the incidence of preeclampsia has increased. Clinical manifestations are highly variable and may occur antepartum, intrapartum, or postpartum. Hypertension and proteinuria are the traditional hallmarks for the diagnosis of preeclampsia. These signs may occur with or without multisystem dysfunction and fetal involvement. Risk factors have been identified for the development of preeclampsia; however, ideal methods for prevention, screening, and treatment remain elusive. Preeclampsia resolves after delivery of the fetus, but patients may still have hypertension postpartum. Women and fetuses affected by preeclampsia are at higher risk of developing long-term health issues. There appear to be risk factors common to hypertensive disorders of pregnancy and cardiovascular disease seen later in adulthood. Physicians providing healthcare to women are urged to recognize potential risk factors that arise from patient obstetric histories so that optimal long-term health surveillance is provided.

Genome-wide association study of pre-eclampsia detects novel maternal single nucleotide polymorphisms and copy-number variants in subsets of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study cohort

A genome-wide association study was undertaken to identify maternal single nucleotide polymorphisms (SNPs) and copy-number variants (CNVs) associated with pre-eclampsia. Case-control analysis was performed on 1070 Afro-Caribbean (n = 21 cases and 1049 controls) and 723 Hispanic (n = 62 cases and 661 controls) mothers and 1257 mothers of European ancestry (n = 50 cases and 1207 controls) from the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study. European ancestry subjects were genotyped on Illumina Human610-Quad and Afro-Caribbean and Hispanic subjects were genotyped on Illumina Human1M-Duo BeadChip microarrays. Genome-wide SNP data were analyzed using PLINK. CNVs were called using three detection algorithms (GNOSIS, PennCNV, and QuantiSNP), merged using CNVision, and then screened using stringent criteria. SNP and CNV findings were compared to those of the Study of Pregnancy Hypertension in Iowa (SOPHIA), an independent pre-eclampsia case-control dataset of Caucasian mothers (n = 177 cases and 116 controls). A list of top SNPs were identified for each of the HAPO ethnic groups, but none reached Bonferroni-corrected significance. Novel candidate CNVs showing enrichment among pre-eclampsia cases were also identified in each of the three ethnic groups. Several variants were suggestively replicated in SOPHIA. The discovered SNPs and copy-number variable regions present interesting candidate genetic variants for pre-eclampsia that warrant further replication and investigation.

The role of the renin-angiotensin-aldosterone system in preeclampsia: genetic polymorphisms and microRNA

The compensatory alterations in the rennin-angiotensin-aldosterone system (RAAS) contribute to the salt-water balance and sufficient placental perfusion for the subsequent well-being of the mother and fetus during normal pregnancy and is characterized by an increase in almost all the components of RAAS. Preeclampsia, however, breaks homeostasis and leads to a disturbance of this delicate equilibrium in RAAS both for circulation and the uteroplacental unit. Despite being a major cause for maternal and neonatal morbidity and mortality, the pathogenesis of preeclampsia remains elusive, where RAAS has been long considered to be involved. Epidemiological studies have indicated that preeclampsia is a multifactorial disease with a strong familial predisposition regardless of variations in ethnic, socioeconomic, and geographic features. The heritable allelic variations, especially the genetic polymorphisms in RAAS, could be the foundation for the genetics of preeclampsia and hence are related to the development of preeclampsia. Furthermore, at a posttranscriptional level, miRNA can interact with the targeted site within the 3'-UTR of the RAAS gene and thereby might participate in the regulation of RAAS and the pathology of preeclampsia. In this review, we discuss the recent achievements of genetic polymorphisms, as well as the interactions between maternal and fetal genotypes, and miRNA posttranscriptional regulation associated with RAAS in preeclampsia. The results are controversial but utterly inspiring and attractive in terms of potential prognostic significance. Although many studies suggest positive associations with genetic mutations and increased risk for preeclampsia, more meticulously designed large-scale investigations are needed to avoid the interference from different variations.

Vascular risk in women with a history of severe preeclampsia

BACKGROUND. To assess markers of vascular dysfunction and risk in postpartum women with a history of severe preeclampsia.

METHODS

Carotid intima-media thickness (CIMT) and brachial artery flow-mediated dilatation (FMD) measured by ultrasonography, and lipid profile and insulin resistance evaluated by biochemical assays were compared between 34 women with a history of severe preeclampsia and 42 women with a prior normal pregnancy at least 12-24 months postpartum.

RESULTS

CIMT was higher and FMD lower in the preeclamptic than in the control group. We found a significant inverse correlation between CIMT and FMD in the preeclamptic group, but no difference in lipid profiles and insulin resistance between the groups.

CONCLUSIONS

Women with a history of severe preeclampsia exhibit early structural and functional preatherosclerotic vascular impairment, which might explain their higher risk of future cardiovascular disease.

The maternal HLA-G 1597ΔC null mutation is associated with increased risk of pre-eclampsia and reduced HLA-G expression during pregnancy in African-American women

The non-classical major histocompatibility complex molecule, human leukocyte antigen (HLA)-G, is thought to contribute to maternal immune tolerance and successful placentation during pregnancy. Genetic polymorphisms in HLA-G are known to influence expression levels as well as the relative expression of individual protein isoforms. As diminished or aberrant HLA-G expression patterns may contribute to the development of certain pregnancy complications, we sought to investigate the association between functional HLA-G polymorphisms and the risk of pre-eclampsia (PE) in African-American women. The association between maternal and fetal genotype at six HLA-G polymorphisms and risk of PE was assessed in 372 pregnancies (314 normotensive; 58 pre-eclamptic). We observed an elevated risk of PE (P = 0.00027) in pregnancies where the mother carried the 1597ΔC allele, a null allele that abolishes expression of full-length HLA-G isoforms. Furthermore, the frequency of the maternal 1597ΔC allele was highest in the subset of pre-eclamptic pregnancies that were delivered preterm, suggesting an association between the null allele and the severity of PE. We then replicated the association between higher maternal 1597ΔC allele frequency and increased severity of PE (P = 0.038) in an independent sample of 533 African-American women. Finally, to investigate the mechanistic basis of this association, we measured circulating soluble HLA-G (sHLA-G) concentrations in maternal serum collected during pregnancy in 51 healthy, normotensive African-American control women and found significantly lower levels in women carrying the 1597ΔC allele (P = 0.012). These results demonstrate that maternal HLA-G genotype is significantly associated with risk of PE in African-American women and is predictive of circulating sHLA-G levels during pregnancy.

Change in paternity and select perinatal outcomes: causal or confounded?

Select social, behavioural and maternal characteristics were evaluated to determine if they were confounding factors in the association between paternity change and pre-eclampsia, small for gestational age (SGA) and pre-term delivery, in a sample of 1,409 women. Multivariate logistic regression analysis was used to determine if any of these risk factors modified the association between changing paternity and the selected perinatal outcomes. Results of the analysis showed that women who changed partners were more likely to possess potentially confounding risk factors compared with those who had not. Paternity change was 2.75 times more likely to be associated with the development of pre-eclampsia (95% CI 1.33; 5.68) and 2.25 times more likely to be associated with an SGA infant on weight (95% CI 1.13; 4.47), after adjusting for selected risk factors. Paternity change remains a significant risk factor for pre-eclampsia and SGA in the presence of select risk factors.

Linking preeclampsia and cardiovascular disease later in life

Preeclampsia (PE), which is defined as new onset hypertension after 20 weeks of pregnancy accompanied by proteinuria, is characterized by inadequate placentation, oxidative stress, inflammation and widespread endothelial dysfunction. A link between PE and long-term risk of cardiovascular disease (CVD) was suggested by retrospective studies, which found that PE was associated with a 2–3-fold risk of CVD later in life, with a 5–7-fold risk in the case of severe and/or early-onset PE. Recently, meta-analyses and prospective studies have confirmed the association between PE and the emergence of an unfavorable CVD risk profile, in particular a 3–5-fold increased prevalence of the metabolic syndrome only 8 years after the index pregnancy. PE and CVD share many risk factors, including obesity, hypertension, dyslipidemia, hypercoagulability, insulin resistance and both entities are characterized by endothelial dysfunction. PE and CVD are complex traits sharing common risk factors and pathophysiological processes, but the genetic link between both remains to be elucidated. However, recent evidence suggests that genetic determinants associated with the metabolic syndrome, inflammation and subsequent endothelial dysfunction are involved. As the evidence now supports that PE represents a risk factor for the emergence of the metabolic syndrome and CVD later in life, the importance of long-term follow-up assessment of CVD risk beginning early in women with a history of PE must be considered and translated into new preventive measures.

Birds, babies and blood

This is an autobiographical review describing the author's career in immunology research and summarizing his current understanding of the areas involved. Contributions to autoimmunity, immune deficiency, transfusion immunology, HLA-disease associations, reproductive immunology, cellular therapies, and innate immunity are included; also discussion of medical research ethics and various research-related activities.