A molecular variant of angiotensinogen associated with preeclampsia

Pertinence between risk of preeclampsia and the renin-angiotensin-aldosterone system (RAAS) gene polymorphisms: an updated meta-analysis based on 73 studies

The aetiological mechanism of preeclampsia (PE) is unclear exactly, so we attempted to investigate the association between susceptibility to preeclampsia and renin-angiotensin-aldosterone system (RAAS) gene polymorphisms to explore the aetiology in terms of genetics. A systematic search was performed in electronic databases to identify relevant studies. Eventually 73 studies were enrolled, odds ratios were generated by 5 genetic models. In overall analysis, significant associations were detected for AGT M235T, AT1R A1166C and CYP11B2 C344T whereas negative correlation was shown for AGT T174M. As stratified by race and geography, AGT 235T allele and AT1R 1166C allele increased preeclampsia risk and AGT T174M was justified uncorrelated with preeclampsia. Our meta-analysis illustrated that AGT 235T allele and AT1R 1166C allele increased and CYP11B2 344T allele decreased preeclampsia risk while AGT T174M polymorphism did not change preeclampsia risk. Hence, pregnant women carrying high-risk genotypes need strengthened management to prevent and early identification of preeclampsia.

Genetic variation in placental insufficiency: What have we learned over time?

Genetic variation shapes placental development and function, which has long been known to impact fetal growth and pregnancy outcomes such as miscarriage or maternal pre-eclampsia. Early epidemiology studies provided evidence of a strong heritable component to these conditions with both maternal and fetal-placental genetic factors contributing. Subsequently, cytogenetic studies of the placenta and the advent of prenatal diagnosis to detect chromosomal abnormalities provided direct evidence of the importance of spontaneously arising genetic variation in the placenta, such as trisomy and uniparental disomy, drawing inferences that remain relevant to this day. Candidate gene approaches highlighted the role of genetic variation in genes influencing immune interactions at the maternal-fetal interface and angiogenic factors. More recently, the emergence of molecular techniques and in particular high-throughput technologies such as Single-Nucleotide Polymorphism (SNP) arrays, has facilitated the discovery of copy number variation and study of SNP associations with conditions related to placental insufficiency. This review integrates past and more recent knowledge to provide important insights into the role of placental function on fetal and perinatal health, as well as into the mechanisms leading to genetic variation during development.

Structural and Dynamic Investigation of non-synonymous variations in Renin-AGT complex revealed altered binding via hydrogen bonding network reprogramming to accelerate the hypertension pathway

Hypertension is one of the major issues worldwide and one of the main factors involved in heart and kidney failure. Angiotensinogen and renin are key components of the renin-angiotensin-aldosterone system (RAAS), which plays an indispensable role in hypertension. The aimed of this study to find out the non-synonymous mutations and structure-based mutation-function correlation in the Renin-AGT complex and reveal the most deleterious mutations to accelerated hypertension. In the current study, we employed computational modelling and molecular simulation approaches to demonstrate the impact of specific mutations in the REN-AGT interface in hypertension. Computational algorithms i.e. PhD-SNP, PolyPhen-1, MAPP, SIFT, SNAP, PredictSNP, PolyPhen-2, and PANTHER predicted 20 mutations as deleterious in AGT while only five mutations were conformed as deleterious in the Renin protein. Investigation of the bonding analysis revealed that two mutations S107L and V193F in Renin altered the hydrogen-bonding paradigm at the interface site. Furthermore, exploration of structural-dynamic behaviors demonstrated by that these mutations also increases the structural stability to regulate the expression of disease pathway. The flexibility index of each residues and structural compactness analysis further validated the findings by portraying the difference in the dynamic behavior in contrast to the wild type. Binding energy calculations based on molecular mechanics/generalized Born surface area (MM/GBSA) methods were used which further established the binding differences between the wild type, S107L, and V193F mutant variants. The total binding energy for wild type, S107L, and V193F were reported to be -27.79 kcal/mol, -47.72 kcal/mol, and -38.25 kcal/mol respectively. In conclusion, these two mutations increase the binding free energy alongside the docking score to enhance the binding between Renin and AGT to overexpress this pathway in a hypertension disease condition. Patients with these mutations may be screened for potential therapeutic intervention.

Preeclampsia, Natural History, Genes, and miRNAs Associated with the Syndrome

Preeclampsia (PE) is a hypertensive disease that affects pregnant women after 20 weeks of gestation. This disease is associated with an important risk of maternal and fetal mortality. PE is described as a placental pathology because, after delivery, most women recover normal arterial pressure. Poor invasion of the spiral arteries is a phenomenon well described in PE; this leads to a hypoxic uterine bed and imbalance of antiangiogenic and proangiogenic factors in the uteroplacental region, which in turn triggers the disease phenotype. The causes of the pathology are unclear; nevertheless, numerous approaches, including next-generation sequencing, association, and case control and miRNA studies, have shed light on the genetic/molecular basis of PE. These studies help us better understand the disease to advance new treatment strategies.

Combined Oral Contraceptive Pill-Induced Hypertension and Hypertensive Disorders of Pregnancy: Shared Mechanisms and Clinical Similarities

PURPOSE OF REVIEW

Oral contraceptive pill-induced hypertension (OCPIH) and hypertensive disorders in pregnancy (HDP) share common risk factors and pathophysiological mechanisms, yet the bidirectional relationship between these two conditions is not well-established. We review and describe OCPIH and HDP to better understand how hormonal and metabolic imbalances affect hypertension.

RECENT FINDINGS

Oral contraceptive pills continue to be a popular method of contraception, with an incidence of OCPIH ranging from 1-8.5% among OCP users. HDP have an incidence of 5-10% of all pregnancies in the USA and have been shown to be a powerful predictor of lifetime adverse cardiovascular outcomes, including future hypertension. OCPIH and HDP share common risk factors such as age, BMI, past personal and family history of hypertension, as well as pathogenic mechanisms, including alterations in hormonal metabolism and the renin angiotensin aldosterone system; imbalance of vasodilator-vasoconstrictor compounds; and changes in the cardiovascular system. Future research should address additional potential mechanisms that underlie hypertension in these two conditions where endocrine changes, either physiological (pregnancy) or iatrogenic (use of OCP), play a role. This may lead to novel, targeted treatment options to improve hypertension management and overall cardiovascular risk profile management in this subset of young female patients.

A study of the association between angiotensinogen (AGT) gene polymorphism (M235T) and preeclampsia in Thai pregnant women

AGT M235T gene polymorphism may cause increased blood pressure in preeclampsia in pregnancy; however, the evidence remains controversial. This study investigated the association between AGT M235T and preeclampsia in Thai pregnant women. A case-control study was conducted to compare the distributions of AGT M235T genotypes and alleles between 142 normotensive pregnancies as controls and 61 preeclampsia pregnancies as cases in a tertiary-care university hospital in Chiang Mai, Thailand. The results show that the distribution of AGT M235T genotypes (MM, MT and TT) of both groups were not significantly different (preeclampsia: 0.0, 16.4, 83.6%; control: 2.1, 22.5, 75.4%, respectively; p = .30). Additionally, there was no statistical difference in the distribution of AGT M235T alleles (M and T alleles) (preeclampsia: 8.2 and 91.8% versus control: 13.4 and 86.6%, respectively; p = .14). In this study, the distributions of AGT M235T were not different in both groups. Therefore, AGT M235T polymorphism may not play a significant role in preeclampsia pathophysiology in Thai population.Impact statementWhat is already known on this subject? Preeclampsia is one of the major complications during pregnancy; it significantly affects maternal and perinatal morbidity and mortality. Effort has been made to find markers and predictors that are associated with the pathophysiology of preeclampsia. AGT M235T gene polymorphism may cause increased blood pressure in preeclampsia pregnancy; however, evidences are still controversial.What do the results of this study add? We conducted a case-control study to compare the distributions of AGT M235T genotypes and alleles between 142 normotensive pregnancies as controls and 61 preeclampsia pregnancies as cases. The results show that preeclamptic women are more likely to deliver at an earlier gestational age and have a smaller baby in comparison with the normotensive group. In addition, women with preeclampsia had a higher chance of having an operative delivery and caesarean section. However, the distribution of AGT M235T polymorphism of preeclampsia women and the control group were not significantly different.What are the implications of these findings for clinical practice and/or further research? AGT M235T polymorphism may not play a significant role in preeclampsia pathophysiology in Thai population.

Male fetal sex affects uteroplacental angiogenesis in growth restriction mouse model†

Abnormally increased angiotensin II activity related to maternal angiotensinogen (AGT) genetic variants, or aberrant receptor activation, is associated with small-for-gestational-age babies and abnormal uterine spiral artery remodeling in humans. Our group studies a murine AGT gene titration transgenic (TG; 3-copies of the AGT gene) model, which has a 20% increase in AGT expression mimicking a common human AGT genetic variant (A[-6]G) associated with intrauterine growth restriction (IUGR) and spiral artery pathology. We hypothesized that aberrant maternal AGT expression impacts pregnancy-induced uterine spiral artery angiogenesis in this mouse model leading to IUGR. We controlled for fetal sex and fetal genotype (e.g., only 2-copy wild-type [WT] progeny from WT and TG dams were included). Uteroplacental samples from WT and TG dams from early (days 6.5 and 8.5), mid (d12.5), and late (d16.5) gestation were studied to assess uterine natural killer (uNK) cell phenotypes, decidual metrial triangle angiogenic factors, placental growth and capillary density, placental transcriptomics, and placental nutrient transport. Spiral artery architecture was evaluated at day 16.5 by contrast-perfused three-dimensional microcomputed tomography (3D microCT). Our results suggest that uteroplacental angiogenesis is significantly reduced in TG dams at day 16.5. Males from TG dams are associated with significantly reduced uteroplacental angiogenesis from early to late gestation compared with their female littermates and WT controls. Angiogenesis was not different between fetal sexes from WT dams. We conclude that male fetal sex compounds the pathologic impact of maternal genotype in this mouse model of growth restriction.

Impact on Longevity of Genetic Cardiovascular Risk and Lifestyle including Red Meat Consumption

Background

Cardiovascular risk (CVR) underlies aging process and longevity. Previous work points to genetic and environmental factors associated with this risk.

Objectives

The aim of this research is to look for any CVR gene-gene and gene-multifactorial/lifestyle interactions that may impact health and disease and underlie exceptional longevity.

Methods

A case-control study involving 521 both gender individuals, 253 centenarians (100.26 ± 1.98 years), and 268 controls (67.51 ± 3.25 years), low (LCR, n = 107) and high (HCR, n = 161) CVR. Hypertension, diabetes, obesity (BMI, kg·m⁻²), and impaired kidney function were defined according to standard criteria. CVR was calculated using Q risk®. DNA was genotyping (ACE-rs4646994, AGT-rs4762, AGR1-rs5182, GRK4-rs2960306, GRK4-rs1024323, NOS3-rs1799983, and SLC12A3-rs13306673) through iPlex-MassARRAY®, read by MALDI-TOF mass spectrometry, and analyzed by EARTDECODE®.

Results

Antilongevity factors consisted (OR 95% CI, p < 0.05) BMI 1.558 (1.445-1.680), hypertension 2.358 (1.565-3.553), smoking habits 4.528 (2.579-7.949), diabetes 5.553 (2.889-10.675), hypercholesterolemia 1.016 (1.010-1.022), and regular consumption of red meat 22.363 (13.987-35.755). Genetic aspects particularly for HCR individuals ACE II (OR: 3.96 (1.83-8.56), p < 0.0001) and NOS3 TT (OR: 3.11 (1.70-5.70), p < 0.0001) genotypes were also risk associate. Obesity, smoking, hypercholesterolemia, and frequent consumption of red meat have an additive action to hypertension in the longevity process. There was a synergistic interaction between the endothelial NOS3 genotypes and the severity of arterial hypertension. An epistatic interaction between functional genetic variants of GRK4 and angiotensinogen was also observed.

Conclusions

Cardiovascular risk-related genetic and multifactorial or predominantly lifestyle aspects and its interactions might influence the aging process and contribute to exceptional longevity in Portuguese centenarians. Besides lifestyle, the activity of nitrite oxide synthase may be one of the main physiologic regulators of cardiovascular protection in the path of longevity.

Fetal Renal DNA Methylation and Developmental Programming of Stress-Induced Hypertension in Growth-Restricted Male Mice

Fetal growth restriction (FGR) is associated with developmental programming of adult onset hypertension, which may be related to differences in nephron development. Prior studies showed that maternal nutrient restriction is associated with reduced nephrogenesis in rodents, especially in male progeny. We hypothesized that maternal genetic risk for FGR may similarly affect fetal kidney development, leading to adult onset hypertension. We employed an angiotensinogen (AGT) gene titration transgenic (TG) construct with 3 copies of the mouse AGT gene that mimics a common human genotype (AGT A[-6]G) associated with FGR. We investigated whether FGR in 2-copy (wild type, [WT]) progeny from 3-copy TG dams leads to developmental programming differences in kidney development and adult blood pressure compared with age- and sex-matched controls. Progeny were tested in the late fetal period (e17.5), neonatal period (2 weeks of age), and as young adults (12 weeks). We measured weights, tested for renal oxidative stress, compared renal DNA methylation profiles, counted the number of glomeruli, and measured adult blood pressure ± stress. Progeny from TG dams were growth restricted with evidence of renal oxidative stress, males showed fetal renal DNA hypermethylation, they had fewer glomeruli, and they developed stress-induced hypertension as adults. Their female siblings did not share this pathology and instead resembled progeny from WT dams. Surprisingly, glomerular counts in the neonatal period were not different between sexes or maternal genotypes. In turn, we suspect that differences in fetal renal DNA methylation may affect the long-term viability of glomeruli, rather than reducing nephrogenesis.

ACOG Practice Bulletin No. 202: Gestational Hypertension and Preeclampsia

Hypertensive disorders of pregnancy constitute one of the leading causes of maternal and perinatal mortality worldwide. It has been estimated that preeclampsia complicates 2-8% of pregnancies globally (). In Latin America and the Caribbean, hypertensive disorders are responsible for almost 26% of maternal deaths, whereas in Africa and Asia they contribute to 9% of deaths. Although maternal mortality is much lower in high-income countries than in developing countries, 16% of maternal deaths can be attributed to hypertensive disorders (). In the United States, the rate of preeclampsia increased by 25% between 1987 and 2004 (). Moreover, in comparison with women giving birth in 1980, those giving birth in 2003 were at 6.7-fold increased risk of severe preeclampsia (). This complication is costly: one study reported that in 2012 in the United States, the estimated cost of preeclampsia within the first 12 months of delivery was $2.18 billion ($1.03 billion for women and $1.15 billion for infants), which was disproportionately borne by premature births (). This Practice Bulletin will provide guidelines for the diagnosis and management of gestational hypertension and preeclampsia.

Non-additive effects of ACVR2A in preeclampsia in a Philippine population

BACKGROUND

Multiple interrelated pathways contribute to the pathogenesis of preeclampsia, and variants in susceptibility genes may play a role among Filipinos, an ethnically distinct group with high prevalence of the disease. The objective of this study was to examine the association between variants in maternal candidate genes and the development of preeclampsia in a Philippine population.

METHODS

A case-control study involving 29 single nucleotide polymorphisms (SNPs) in 21 candidate genes was conducted in 150 patients with preeclampsia (cases) and 175 women with uncomplicated normal pregnancies (controls). Genotyping for the GRK4 and DRD1 gene variants was carried out using the TaqMan Assay, and all other variants were assayed using the Sequenom MassARRAY Iplex Platform. PLINK was used for SNP association testing. Multilocus association analysis was performed using multifactor dimensionality reduction (MDR) analysis.

RESULTS

Among the clinical factors, older age (P <  1 × 10-4), higher BMI (P <  1 × 10-4), having a new partner (P = 0.006), and increased time interval from previous pregnancy (P = 0.018) associated with preeclampsia. The MDR algorithm identified the genetic variant ACVR2A rs1014064 as interacting with age and BMI in association with preeclampsia among Filipino women.

CONCLUSIONS

The MDR algorithm identified an interaction between age, BMI and ACVR2A rs1014064, indicating that context among genetic variants and demographic/clinical factors may be crucial to understanding the pathogenesis of preeclampsia among Filipino women.

Causes and Consequences of the Dysregulated Maternal Renin-Angiotensin System in Preeclampsia

A healthy pregnancy outcome depends on the activation of the renin-angiotensin-aldosterone system (RAAS) as a regulated, integrated response to the growing demands of the conceptus. Both the circulating RAAS and the intrarenal renin-angiotensin system (iRAS) play major roles in cardiovascular function and fluid and electrolyte homeostasis. The circulating RAAS becomes dysfunctional in preeclampsia and we propose that dysregulation of the iRAS plays a role in development of the clinical syndrome known as preeclampsia. Experimental studies in animals have shown that placental renin, when released into the maternal circulation, can cause hypertension. We postulate that abnormal placental development is associated with over-secretion of renin and other RAS proteins/angiotensin (Ang) peptides by the placenta/decidua into the maternal circulation. We hypothesise that this is because of increased shedding of exosomes and other placental particles into the maternal circulation that not only contain RAS proteins and peptides but also microRNAs (miRNAs) that target RAS mRNAs, and Ang II type 1 receptor autoantibodies (AT₁R-AAs), that are agonists for, and have the same actions as, Ang II. As a result, there is both suppression of the circulating RAAS that is responsible for maintaining maternal homeostasis and activation of the iRAS. Together with altered vascular reactivity to Ang peptides, the iRAS causes hypertension, renal damage and secondary changes in the neurohumoral control of the maternal circulation and fluid and electrolyte balance, which contribute to the pathophysiology of preeclampsia.

Obesity and Preeclampsia: Common Pathophysiological Mechanisms

Preeclampsia is a disorder specific of the human being that appears after 20 weeks of pregnancy, characterized by new onset of hypertension and proteinuria. Abnormal placentation and reduced placental perfusion associated to impaired trophoblast invasion and alteration in the compliance of uterine spiral arteries are the early pathological findings that are present before the clinical manifestations of preeclampsia. Later on, the endothelial and vascular dysfunction responsible of the characteristic vasoconstriction of preeclampsia appear. Different nutritional risk factors such as a maternal deficit in the intake of calcium, protein, vitamins and essential fatty acids, have been shown to play a role in the genesis of preeclampsia, but also an excess of weight gain during pregnancy or a pre-pregnancy state of obesity and overweight, which are associated to hyperinsulinism, insulin resistance and maternal systemic inflammation, are proposed as one of the mechanism that conduce to endothelial dysfunction, hypertension, proteinuria, thrombotic responses, multi-organ damage, and high maternal mortality and morbidity. Moreover, it has been demonstrated that pregnant women that suffer preeclampsia will have an increased risk of future cardiovascular disease and related mortality in their later life. In this article we will discuss the results of studies performed in different populations that have shown an interrelationship between obesity and overweight with the presence of preeclampsia. Moreover, we will review some of the common mechanisms that explain this interrelationship, particularly the alterations in the L-arginine/nitric oxide pathway as a crucial mechanism that is common to obesity, preeclampsia and cardiovascular diseases.

Structural basis for the specificity of renin-mediated angiotensinogen cleavage

The renin–angiotensin cascade is a hormone system that regulates blood pressure and fluid balance. Renin-mediated cleavage of the angiotensin I peptide from the N terminus of angiotensinogen (AGT) is the rate-limiting step of this cascade; however, the detailed molecular mechanism underlying this step is unclear. Here, we solved the crystal structures of glycosylated human AGT (2.30 Å resolution), its encounter complex with renin (2.55 Å), AGT cleaved in its reactive center loop (RCL; 2.97 Å), and spent AGT from which the N-terminal angiotensin peptide was removed (2.63 Å). These structures revealed that AGT undergoes profound conformational changes and binds renin through a tail-into-mouth allosteric mechanism that inserts the N terminus into a pocket equivalent to a hormone-binding site on other serpins. These changes fully extended the N-terminal tail, with the scissile bond for angiotensin release docked in renin's active site. Insertion of the N terminus into this pocket accompanied a complete unwinding of helix H of AGT, which, in turn, formed key interactions with renin in the complementary binding interface. Mutagenesis and kinetic analyses confirmed that renin-mediated production of angiotensin I is controlled by interactions of amino acid residues and glycan components outside renin's active-site cleft. Our findings indicate that AGT adapts unique serpin features for hormone delivery and binds renin through concerted movements in the N-terminal tail and in its main body to modulate angiotensin release. These insights provide a structural basis for the development of agents that attenuate angiotensin release by targeting AGT's hormone binding pocket.

Contribution of angiotensinogen M235T and T174M gene variants and haplotypes to preeclampsia and its severity in (North African) Tunisians

BACKGROUND

Preeclampsia (PE) is a pregnancy-associated hypertensive disorder and a leading cause of maternal and neonatal morbidity and mortality. While its pathogenesis remains ill defined, several candidate genes for PE have been identified, but results remain inconclusive. We investigated the association of the angiotensinogen ( AGT) gene variants M235T and T174M with PE, and we analyzed the contribution of both variants to the severity of PE.

METHODS

This case-control study enrolled 550 Tunisian pregnant women: 272 with PE, of whom 147 presented with mild, and 125 with severe PE, along with 278 unrelated age- and ethnically matched control women. AGT genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Significantly higher M235T minor allele frequency (MAF) was associated with increased risk of PE ( p < 0.001). Decreased frequency of heterozygous T174M genotype carriers were found in control women ( p = 0.015), suggesting a protective effect of this genotype (odds ratio (95% confidence interval) = 0.51 (0.29-0.89)). Two-locus haplotype analysis demonstrated MM and TT haplotypes to be negatively and positively associated with PE, respectively. MAF of M253T, but not T174M, was higher in the severe PE group, and carrying M235T or T174M minor allele was associated with increased body mass index ( p < 0.001) among unselected PE women.

CONCLUSIONS

AGT M235T and T174M variants contribute to an increased risk of developing PE, and for M235T to PE severity.

Renin angiotensin aldosterone inhibition in the treatment of cardiovascular disease

A collective century of discoveries establishes the importance of the renin angiotensin aldosterone system in maintaining blood pressure, fluid volume and electrolyte homeostasis via autocrine, paracrine and endocrine signaling. While research continues to yield new functions of angiotensin II and angiotensin-(1-7), the gap between basic research and clinical application of these new findings is widening. As data accumulates on the efficacy of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers as drugs of fundamental importance in the treatment of cardiovascular and renal disorders, it is becoming apparent that the achieved clinical benefits is suboptimal and surprisingly no different than what can be achieved with other therapeutic interventions. We discuss this issue and summarize new pathways and mechanisms effecting the synthesis and actions of angiotensin II. The presence of renin-independent non-canonical pathways for angiotensin II production are largely unaffected by agents inhibiting renin angiotensin system activity. Hence, new efforts should be directed to develop drugs that can effectively block the synthesis and/or action of intracellular angiotensin II. Improved drug penetration into cardiac or renal sites of disease, inhibiting chymase the primary angiotensin II forming enzyme in the human heart, and/or inhibiting angiotensinogen synthesis would all be more effective strategies to inhibit the system. Additionally, given the role of angiotensin II in the maintenance of renal homeostatic mechanisms, any new inhibitor should possess greater selectivity of targeting pathogenic angiotensin II signaling processes and thereby limit inappropriate inhibition.

The Gene Variants of Maternal/Fetal Renin-Angiotensin System in Preeclampsia: A Hybrid Case-Parent/Mother-Control Study

Preeclampsia (PE) is a common pregnancy-related complication, and polymorphisms in angiotensinogen (AGT), angiotensin-converting enzyme (ACE), and angiotensin II type 1 receptor (AT1R) are believed to contribute to PE development. We implemented a hybrid study to investigate the influence of maternal and fetal ACE I/D, ACE G2350A, AGT M235T, AGT T174M, and AT1R A1166C polymorphisms on PE in Han Chinese women. Polymorphisms were genotyped in 1,488 subjects (256 patients experiencing PE, along with their fetuses and partners, and 360 normotensive controls with their fetuses). Transmission disequilibrium tests revealed that ACE I/D (P = 0.041), ACE G2350A (P = 0.035), and AT1R A1166C (P = 0.018) were associated with maternal PE. The log-linear analyses revealed that mothers whose offspring carried the MM genotype of AGT M235T had a higher risk of PE (OR = 1.54, P = 0.010), whereas mothers whose offspring carried the II genotype of ACE I/D or the GG genotype of ACE G2350A had a reduced risk (OR = 0.58, P = 0.039; OR = 0.47, P = 0.045, respectively). Our findings demonstrate that fetal ACE I/D, ACE G2350A, AGT M235T, and AT1R A1166C polymorphisms may play significant roles in PE development among pregnant Han Chinese women.

Renin-angiotensin system transgenic mouse model recapitulates pathophysiology similar to human preeclampsia with renal injury that may be mediated through VEGF

Using a transgenic cross, we evaluated features of preeclampsia, renal injury and the sFlt1/VEGF changes. Transgenic hAGT and hREN, or wild-type (WT) C57Bl/6 mice were cross-bred: female hAGT × male hREN for preeclampsia (PRE) model and female WT × male WT for pregnant controls (WTP). Samples were collected for plasma VEGF, sFlt1, and urine albumin. Blood pressures (BP) were monitored by telemetry. Vascular reactivity was investigated by wire myography. Kidneys and placenta were immunostained for sFlt1 and VEGF. Eleven PRE and 9 WTP mice were compared. PRE more frequently demonstrated albuminuria, glomerular endotheliosis (80% vs. 11%; P = 0.02), and placental necrosis (60% vs. 0%; P < 0.01). PRE group demonstrated declining BPs with advancing gestation. Plasma sFlt1 increased across pregnancy in PRE; VEGF did not vary. IHC demonstrated the presence of sFlt1 in glomeruli, lymphatics, and collecting tubules of PRE kidneys, suggesting excretion. VEGF immunostaining was increased specifically in the glomeruli of PRE kidneys. Placenta in PRE showed marked immunostaining for sFlt1. We conclude that this transgenic model of preeclampsia recapitulates human preeclamptic state with high fidelity, and that, vascular adaptation to pregnancy is suggested by declining BPs and reduced vascular response to PE and increased response to acetylcholine. Placental damage with resultant increased release of sFlt1, proteinuria, deficient spiral artery remodeling, and glomerular endotheliosis were observed in this model of PRE. Increased VEGF binding to glomerular endothelial cells in this model of PRE is similar to human PRE and leads us to hypothesize that renal injury in preeclampsia may be mediated through local VEGF.

Epidemiology of hypertensive disorders in pregnancy: prevalence, risk factors, predictors and prognosis

Hypertensive disorders in pregnancy (HDP) represent some of the most important problems faced by public health because HDP is a major cause of maternal and prenatal morbidity and mortality. Several epidemiological studies have been performed to determine the prevalence and risk factors of HDP as well as its subtypes. The prevalences of HDP, gestational hypertension and preeclampsia are 5.2-8.2%, 1.8-4.4% and 0.2-9.2%, respectively. Body mass index, anemia and lower education appear to be modifiable risk factors for HDP. Maternal age, primiparous, multiple pregnancy, HDP in previous pregnancy, gestational diabetes mellitus, preexisting hypertension, preexisting type 2 diabetes mellitus, preexisting urinary tract infection and a family history of hypertension, type 2 diabetes mellitus and preeclampsia appear to be nonmodifiable risk factors. Genetic variants including a single-nucleotide polymorphism in the angiotensinogen gene have also been reported to be nonmodifiable risk factors. Epidemiological studies have recently examined the associations between a history of HDP and its subtypes and future risks of other diseases. These studies have reported associations between a history of HDP and a risk of coronary heart disease, heart failure, dysrhythmia, stroke, hypertension, diabetes mellitus, end-stage renal dysfunction and cardiomyopathy. HDP is not associated with the future incidence of total cancer. In conclusion, HDP is not a rare complication of pregnancy and the influence of HDP remains for an extended duration. Physicians should consider the effects of HDP when treating chronic diseases in women.

Polymorphisms in the Endothelial Nitric Oxide Synthase Gene May Be Protective Against Preeclampsia in a Chinese Population

The association between the endothelial nitric oxide synthase (eNOS) gene with vascular diseases in Western populations and with severe preeclampsia (PE) in the Japanese population have been demonstrated, lacing the data in Chinese population. The authors examine the association between PE and 2 polymorphisms of the eNOS gene in a Chinese population, consisting of 92 pregnant women with PE and 256 healthy controls. All were genotyped for the Glu298Asp polymorphism in exon 7 and the number of 27 base pair repeats in intron 4 of the eNOS gene. The frequencies of both the variant T allele and eNOS 4a (small allele with 4 repeats of 27 bp) were significantly lower in the PE group than in the control group. The genotype distribution of Glu298Glu, Glu298Asp, and Asp298Asp in eNOS exon 7 and bb type and ab type in eNOS intron 4 revealed statistically significant differences between control and PE groups. This is the first study to evaluate the association between 2 polymorphisms in the maternal eNOS gene with PE simultaneously in a Chinese population. Similar to the findings in Western populations, polymorphisms in the eNOS gene may be protective against PE in a Chinese population, in contrast to the results in the Japanese population.

Estrogen Receptor Alpha (ESR1) Gene Polymorphisms in Pre-eclamptic Saudi Patients

OBJECTIVES

Pre-eclampsia causes maternal mortality worldwide. Estrogen receptor alpha (ESR1) gene polymorphisms were responsible for cardiovascular diseases. This case control study was conducted to investigate whether 2 polymorphic genes of ESR1 are associated with pre-eclampsia among Saudi women in Madina city, Saudi Arabia.

METHODS

Blood samples from 97 pre-eclamptic and 94 healthy pregnant women were analyzed using restriction fragment length polymorphism-polymerase chain reaction method. All the subjects were recruited randomly from outpatient clinics of Madina Maternity Children Hospital (MMCH), Madina, Saudi Arabia, between Dec. 2012 and Jan. 2014.

RESULTS

There was no association between pre-eclampsia and PvuII and XbaI ESR1 gene polymorphisms individually. TT/AA and TT/AG genotype combination existed significantly in pre-eclamptic patients compared to control. The frequency of PvuII and XbaI combined TT/AA genotypes between pre-eclamptic women was 36.1% vs 9.6%, however, frequency of PvuII and XbaI combined TT/AG genotypes between pre-eclamptic women was 3.1% vs 17%, compared to control. The homozygous T-A haplotype carriers showed high pre-eclampsia risk, independent of pregnancy, BMI and smoking status (adjusted odds ratio (OR): 3.26, 95% confidence interval (CI):1.71-9.21). The heterozygous T-A haplotype carriers did not differ from that of non-carriers (adjusted OR: 1.12, 95% CI: 0.47-2.75). No association was observed between pre-eclampsia and T-G, C-G and C-A haplotype of PvuII and XbaIESR1 gene polymorphisms.

CONCLUSIONS

T-A haplotype of homozygous associated with pre eclampsia not heterozygous carriers of ESR 1 PvuII and XbaI gene polymorphisms elicited high risk of pre-eclampsia. GG genotype of XbaI polymorphism decreased pre-eclampsia risk. Further studies using larger sample size are recommended to investigate the ESR 1 gene polymorphisms associated with pre-eclampsia.

Classical Renin-Angiotensin system in kidney physiology

The renin-angiotensin system has powerful effects in control of the blood pressure and sodium homeostasis. These actions are coordinated through integrated actions in the kidney, cardiovascular system and the central nervous system. Along with its impact on blood pressure, the renin-angiotensin system also influences a range of processes from inflammation and immune responses to longevity. Here, we review the actions of the "classical" renin-angiotensin system, whereby the substrate protein angiotensinogen is processed in a two-step reaction by renin and angiotensin converting enzyme, resulting in the sequential generation of angiotensin I and angiotensin II, the major biologically active renin-angiotensin system peptide, which exerts its actions via type 1 and type 2 angiotensin receptors. In recent years, several new enzymes, peptides, and receptors related to the renin-angiotensin system have been identified, manifesting a complexity that was previously unappreciated. While the functions of these alternative pathways will be reviewed elsewhere in this journal, our focus here is on the physiological role of components of the "classical" renin-angiotensin system, with an emphasis on new developments and modern concepts.

Dexamethasone promotes hypertension by allele-specific regulation of the human angiotensinogen gene

The human angiotensinogen (hAGT) gene has polymorphisms in its 2.5-kb promoter that form two haplotype (Hap) blocks: -6A/G (-1670A/G, -1562C/T, and -1561T/C) and -217A/G (-532T/C, -793A/G, -1074T/C, and -1178G/A). Hap -6A/-217A is associated with human hypertension, whereas Hap -6G/-217G reduces cardiovascular risk. Hap -6A/-217A has increased promoter activity with enhanced transcription factor binding, including to the glucocorticoid receptor (GR). Glucocorticoid therapy frequently causes hypertension, the mechanisms for which are incompletely understood. We have engineered double transgenic (TG) mice containing the human renin gene with either Hap of the hAGT gene and examined the physiological significance of glucocorticoid-mediated allele-specific regulation of the hAGT gene. We have also studied the consequential effects on the renin angiotensin system and blood pressure. TG mice with Hap -6A and -6G were treated with and without a low dose of a GR agonist, dexamethasone (2.5 μg/ml), for 72 h. We found greater chromatin-GR binding with increased GR agonist-induced hAGT expression in liver and renal tissues of Hap -6A mice. Additionally, dexamethasone treatment increased circulating hAGT and angiotensin II levels in Hap -6A mice, as compared with -6G mice. Importantly, GR agonist significantly increased blood pressure and redox markers in TG mice with Hap-6A of the hAGT gene. Taken together, our results show, for the first time, that glucocorticoids affect hAGT expression in a haplotype-dependent fashion with SNPs in Hap -6A favoring agonist-induced GR binding. This leads to increased expression of the hAGT, up-regulation of the renin angiotensin system, and increased blood pressure and oxidative stress in Hap -6A mice.

Administration of angiotensin II and a bradykinin B2 receptor blocker in midpregnancy impairs gestational outcome in guinea pigs

BACKGROUND

The opposing renin-angiotensin system (RAS) and kallikrein-kinin system (KKS) are upregulated in pregnancy and localize in the utero-placental unit. To test their participation as counter-regulators, circulating angiotensin II (AII) was exogenously elevated and the bradykinin B2 receptor (B2R) was antagonized in pregnant guinea-pigs. We hypothesized that disrupting the RAS/KKS balance during the period of maximal trophoblast invasion and placental development would provoke increased blood pressure, defective trophoblast invasion and a preeclampsia-like syndrome.

METHODS

Pregnant guinea-pigs received subcutaneous infusions of AII (200 μg/kg/day), the B2R antagonist Bradyzide (BDZ; 62.5 microg/kg/day), or both (AII + BDZ) from gestational day 20 to 34. Non-pregnant cycling animals were included in a control group (C NP) or received AII + BDZ (AII + BDZ NP) during 14 days. Systolic blood pressure was determined during cycle in C NP, and on the last day of infusion, and 6 and 26 days thereafter in the remaining groups. Twenty six days after the infusions blood and urine were extracted, fetuses, placentas and kidneys were weighed, and trophoblast invasion of spiral arteries was defined in the utero-placental units by immunocytochemistry.

RESULTS

Systolic blood pressure transiently rose in a subgroup of the pregnant females while receiving AII + BDZ infusion, but not in AII + BDZ NP. Plasma creatinine was higher in AII- and BDZ-treated dams, but no proteinuria or hyperuricemia were observed. Kidney weight increased in AII + BDZ-treated pregnant and non-pregnant females. Aborted and dead fetuses were increased in dams that received AII and AII + BDZ. The fetal/placental weight ratio was reduced in litters of AII + BDZ-treated mothers. All groups that received interventions during pregnancy showed reduced replacement of endothelial cells by extravillous trophoblasts in lateral and myometrial spiral arteries.

CONCLUSIONS

The acute effects on fetal viability, and the persistently impaired renal/placental sufficiency and incomplete arterial remodeling implicate the RAS and KKS in the adaptations in pregnancy. The results partially confirm our hypothesis, as a preeclampsia-like syndrome was not induced. We demonstrate the feasibility of characterizing systemic and local modifications in pregnant guinea-pig, supporting its use to study normal placentation and related disorders.

Hypoxia-induced endothelial progenitor cell function is blunted in angiotensinogen knockout mice

Angiotensinogen (AGT), the precursor of angiotensin I, is known to be involved in tumor angiogenesis and associated with the pathogenesis of coronary atherosclerosis. This study was undertaken to determine the role played by AGT in endothelial progenitor cells (EPCs) in tumor progression and metastasis. It was found that the number of EPC colonies formed by AGT heterozygous knockout (AGT(+/-)) cells was less than that formed by wild-type (WT) cells, and that the migration and tube formation abilities of AGT(+/-) EPCs were significantly lower than those of WT EPCs. In addition, the gene expressions of vascular endothelial growth factor (VEGF), Flk1, angiopoietin (Ang)-1, Ang-2, Tie-2, stromal derived factor (SDF)-1, C-X-C chemokine receptor type 4 (CXCR4), and of endothelial nitric oxide synthase (eNOS) were suppressed in AGT(+/-) EPCs. Furthermore, the expressions of hypoxia-inducible factor (HIF)-1α and -2α were downregulated in AGT(+/-) early EPCs under hypoxic conditions, suggesting a blunting of response to hypoxia. Moreover, the activation of Akt/eNOS signaling pathways induced by VEGF, epithelial growth factor (EGF), or SDF-1α were suppressed in AGT(+/-) EPCs. In AGT(+/-) mice, the incorporation of EPCs into the tumor vasculature was significantly reduced, and lung tumor growth and melanoma metastasis were attenuated. In conclusion, AGT is required for hypoxia-induced vasculogenesis.

eNOSI4 and EPHX1 polymorphisms affect maternal susceptibility to preeclampsia: analysis of five polymorphisms predisposing to cardiovascular disease in 279 Caucasian and 241 African women

PURPOSE

The aim of this study was to evaluate possible associations of genetic polymorphisms predisposing to cardiovascular disease with the development and/or the severity of preeclampsia.

METHODS

A two hospital-based prospective case-control study was performed in Germany and Ghana. 470 blood samples of 250 Caucasian and 220 black African have been genotyped by pyrosequencing and fragment length analysis. We evaluated the distribution of the epoxide hydrolase 1 (EPHX1) polymorphism on exon 3, the endothelial nitric oxide synthase (eNOS) polymorphisms on exon 7 and on intron 4, the angiotensinogen polymorphism on exon 2 and the estrogen receptor 1 polymorphism in intron 1.

RESULTS

74 Caucasian and 84 African were classified as preeclampsia with 27 Caucasian developing a hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome and 17 African women experiencing eclampsia. Multivariate logistic regression analysis adjusting for ethnicity, age and parity revealed for carriers of eNOSI4 VNTR4a a 1.7-fold increased (95% CI 1.10-2.711, p = 0.016) risk to develop preeclampsia and a 3.6-fold increase for carriers of the EPHX1 113Tyr (95% CI 1.366-8.750, p = 0.009) to develop severest preeclampsia.

CONCLUSION

Our finding of eNOSI4 polymorphism predisposing to preeclampsia independently of ethnicity, age and parity supports the concept of NO being involved in the endothelial disorder preeclampsia. Since EPHX1 is highly expressed in the liver, can interact with various signaling pathways and is involved in central nervous system disorders, the association of EPHX1 polymorphism with the HELLP syndrome and eclampsia may hint to EPHX being a further key player in the pathogenesis of preeclampsia.

Preeclampsia: a "nephrocentric" view

To the obstetrician, preeclampsia is a placental syndrome becoming clinically apparent in later pregnancy and presenting with maternal hypertension, proteinuria, and in some cases liver and central nervous system dysfunction, which, if not addressed in a timely fashion can lead to significant maternal and fetal morbidity and mortality. As such, the only satisfactory cure is delivery of the fetus, after which most, if not all, of the manifestations disappear. The nephrologist, who often is consulted only when patients develop more serious manifestations such as accelerating hypertension, acute kidney injury, and microangiopathic features, often has a different perspective. She/he sees a woman with hypertension and proteinuric kidney disease with mildly reduced glomerular filtration rate. Exciting discoveries regarding the pathogenesis of this syndrome have helped to reconcile these two views; however, much remains unknown. This review focuses on the hypertension and kidney manifestations of the disease, acknowledging that complex placental pathogenic alterations are clearly an important, if not the most important, initiator of the later maternal signs and symptoms.

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.

Human loci involved in drug biotransformation: worldwide genetic variation, population structure, and pharmacogenetic implications

Understanding the role of inheritance in individual variation in drug response is the focus of pharmacogenetics (PGx). A key part of this understanding is quantifying the role of genetic ancestry in this phenotypic outcome. To provide insight into the relationship between ethnicity and drug response, this study first infers the global distribution of PGx variation and defines its structure. Second, the study evaluates if geographic population structure stems from all PGx loci in general, or if structure is caused by specific genes. Lastly, we identify the genetic variants contributing the greatest proportion of such structure. Our study describes the global genetic structure of PGx loci across the 52 populations of the Human Genome Diversity Cell-Line Panel, the most inclusive set of human populations freely available for studies on human genetic variation. By analysing genetic variation at 1,001 single nucleotide polymorphisms (SNPs) involved in biotransformation of exogenous substances, we describe the between-populations PGx variation, as well geographical groupings of diversity. In addition, with discriminant analysis of principal component (DAPC), we infer how many and which groups of populations are supported by PGx variation, and identify which SNPs actually contribute to the PGx structure between such groups. Our results show that intergenic, synonymous and non-synonymous SNPs show similar levels of genetic variation across the globe. Conversely, loci coding for Cytochrome P450s (mainly metabolizing exogenous substances) show significantly higher levels of genetic diversity between populations than the other gene categories. Overall, genetic variation at PGx loci correlates with geographic distances between populations, and the apportionment of genetic variation is similar to that observed for the rest of the genome. In other words, the pattern of PGx variation has been mainly shaped by the demographic history of our species, as in the case of most of our genes. The population structure defined by PGx loci supports the presence of six genetic clusters reflecting geographic location of samples. In particular, the results of the DAPC analyses show that 27 SNPs substantially contribute to the first three discriminant functions. Among these SNPs, some, such as the intronic rs1403527 of NR1I2 and the non-synonymous rs699 of AGT, are known to be associated with specific drug responses. Their substantial variation between different groups of populations may have important implications for PGx practical applications.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Renin-angiotensin system in pre-eclampsia: everything old is new again

This review presents an update of the role of the renin-angiotensin system in normal pregnancy and pre-eclampsia. We have known for years that the circulatory renin-angiotensin system in pre-eclampsia is suppressed. We now know that the circulating renin-angiotensin system does not only have a vasoconstrictor arm, but also a vasodilator arm, which is upregulated in normal pregnancy; this balance is probably disturbed in pre-eclampsia. Recent studies show the importance of the local renin-angiotensin system in the uteroplacental unit for early placentation and regulation of placental blood flow. We discuss the possible role of autoantibodies against the AT1-receptor in pre-eclampsia and the suggestion that activation of the AT1-receptor in the placenta may lead to placental dysfunction and the clinical syndrome of pre-eclampsia.

Angiotensinogen gene M235T and T174M polymorphisms and susceptibility of pre-eclampsia: a meta-analysis

There are controversies in reports on the association of the angiotensinogen (AGT) gene polymorphisms with the risk of developing pre-eclampsia (PE). We performed a meta-analysis to examine the association between the AGT polymorphisms and PE risk: M235T (31 studies involving 2555 patients and 6114 controls) and T174M (six studies involving 681 patients and 2076 controls). For the M235T polymorphism, the TT genotype increased the PE risk as compared to the MM genotype (odds ratio 1.61, 95% confidence intervals 1.22-2.14, P= 0.001). When stratified by ethnicity, the TT genotype remained significantly associated with higher PE risk in Caucasians and Mongolians but not in Africans. Similar results were also obtained under all three genetic models of the M235T polymorphism. For the T174M polymorphism, no significant association was found in the comparisons (MT vs. TT and MM vs. TT) and under any genetic models. The analysis excluding the highly significant Hardy-Weinberg equilibrium-violating studies and sensitivity analysis further strengthened the validity of these associations. No publication bias was observed in this study. This meta-analysis demonstrates that the AGT M235T polymorphism is significantly associated with PE whereas the T174M polymorphism is not.

Synergistic effects of angiotensinogen -217 G→A and T704C (M235T) variants on the risk of severe preeclampsia

BACKGROUND

The rate-limiting step of the renin-angiotensin system is the enzymatic cleavage of angiotensinogen (AGT) by renin. The aims of the present study were to investigate the association between AGT T704C (M235T) and -217 G→A polymorphisms with the risk of preeclampsia and synergistic effects of both polymorphisms on the susceptibility to preeclampsia.

METHODS

We studied AGT variants in 170 women with preeclampsia, including 84 women with mild and 86 women with severe forms of preeclampsia, and 100 age and parity matched controls.

RESULTS

There was a trend towards increased risk of severe preeclampsia in the presence of -217 AA (odds ratio (OR)=1.5, 95% confidence interval (CI)= 0.38-5.84, p=0.57) and TC+CC genotypes (OR=1.32, 95% CI= 0.67-2.58, p=0.42). However, the interaction of both alleles of -217A and 704C highly increased the risk of severe preeclampsia, by 2.23-fold, although this did not reach statistical significance. The frequency of the CC genotype of the T704C polymorphism in early-onset preeclampsia tended to be higher (35%) compared with that in patients with late-onset preeclampsia (21.7%).

CONCLUSIONS

The present study demonstrates that both variants of AGT -217 G→A and T704C might work in synergism to influence the risk of severe preeclampsia, which needs to be confirmed in studies with larger sample size.

Genetic factors associated with small for gestational age birth and the use of human growth hormone in treating the disorder

The term small for gestational age (SGA) refers to infants whose birth weights and/or lengths are at least two standard deviation (SD) units less than the mean for gestational age. This condition affects approximately 3%–10% of newborns. Causes for SGA birth include environmental factors, placental factors such as abnormal uteroplacental blood flow, and inherited genetic mutations. In the past two decades, an enhanced understanding of genetics has identified several potential causes for SGA. These include mutations that affect the growth hormone (GH)/insulin-like growth factor (IGF)-1 axis, including mutations in the IGF-1 gene and acid-labile subunit (ALS) deficiency. In addition, select polymorphisms observed in patients with SGA include those involved in genes associated with obesity, type 2 diabetes, hypertension, ischemic heart disease and deletion of exon 3 growth hormone receptor (d3-GHR) polymorphism. Uniparental disomy (UPD) and imprinting effects may also underlie some of the phenotypes observed in SGA individuals. The variety of genetic mutations associated with SGA births helps explain the diversity of phenotype characteristics, such as impaired motor or mental development, present in individuals with this disorder. Predicting the effectiveness of recombinant human GH (hGH) therapy for each type of mutation remains challenging. Factors affecting response to hGH therapy include the dose and method of hGH administration as well as the age of initiation of hGH therapy. This article reviews the results of these studies and summarizes the success of hGH therapy in treating this difficult and genetically heterogenous disorder.

AGT M235T polymorphism contributes to risk of preeclampsia: evidence from a meta-analysis

Objective: Preeclampsia a hypertensive disorder of pregnancy that mainly manifests as high blood pressure and proteinuria. Angiotensinogen (AGT) plays important roles in the regulation of blood pressure. The purpose of this study was to investigate the relationship between AGT M235T polymorphism and risk of preeclampsia using a meta-analysis. Methods: In this meta-analysis, 22 studies were selected by searching PubMed, EMBASE, ISI and CNKI databases up to October 2011. Crude odds ratios with corresponding 95% confidence intervals were used to evaluate the association between the AGT M235T polymorphism and risk of preeclampsia. Subgroup analyses were conducted by ethnicity and parity. Results: The TT genotype of the AGT M235T polymorphism was associated with elevated risk of preeclampsia in the overall analysis. In subgroup analysis according to ethnicity, increased risks were also found in Caucasians. After stratification based on parity, the excess risk was found in multigravida. Conclusions: These results showed that the TT genotype may play critical roles in the development of preeclampsia.

Association between Val158Met functional polymorphism in the COMT gene and risk of preeclampsia in a Chinese population

BACKGROUND AND AIMS

The catechol-O-methyltransferase (COMT) gene is a potential candidate in altering risk for preeclampsia due to the important enzymatic effects in the metabolism of steroid hormones. It contains a non-synonymous G-A base change at codon 158 in the membrane bound isoform, which leads to a valine-to-methionine amino acid substitution. In the soluble isoform the polymorphism rs4680 is located in codon 108. The variant allele is the Met (A) allele and the Val (G) allele is the wild type allele. Despite its previously reported association with preeclampsia in genotypes in three selected ethnic groups, further studies in other populations are required.

METHODS

We genotyped the Val158Met polymorphism in the COMT gene by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) analysis in a Chinese population.

RESULTS

In the case-control study that included 187 patients with preeclampsia (cases) and 189 normal subjects (controls), the AA genotype and variant Met allele frequencies of Val158Met in the COMT gene were significantly higher in patients with preeclampsia than those in the control group (both p <0.05). The odds ratio for the risk of preeclampsia was 2.395 [95% confidence interval (CI): 1.061-5.408] in women homozygous for the variant COMT allele (χ(2) = 4.649, p = 0.031). Furthermore, it showed that obese women homozygous for the variant COMT allele (Met/Met) had higher diastolic blood pressure levels during pregnancy than wild-type homozygotes (Val/Val) (p = 0.034).

CONCLUSIONS

Our study provided evidence in favor of COMT being a candidate gene for conferring genetic susceptibility to preeclampsia in a South West Chinese population.

Angiotensinogen G(–6)A Polymorphism Is Associated With the Elevation of Blood Pressure in the Hypertensive Disorders of Pregnancy

The objective of the present study was to determine whether angiotensinogen G(–6)A polymorphism is associated with the elevation of blood pressure (BP) in the hypertensive disorders of pregnancy in Korean population. The subjects included 201 cases with the hypertensive disorders of pregnancy and 160 healthy controls. The medical records of subjects were reviewed. Cases were classified into the four subtypes (transient hypertension, preeclampsia, chronic hypertension, and preeclampsia superimposed on chronic hypertension) by the diagnostic criteria suggested by the National High Blood Pressure Education Program Working Group. Cases were also divided into the high and low BP group by the elevation of BP (diastolic BP greater than or equal to 110 mmHg). Maternal angiotensinogen G(–6)A polymorphism was determined by restriction fragment length polymorphism. Frequencies of AA genotype were significantly higher in the high than in the low BP group in the preeclampsia, superimposed preeclampsia, and the combined group (N = 201), suggesting that the angiotensinogen G(–6)A allele was significantly associated with the elevation of BP in the hypertensive disorders of pregnancy among South Korean women. The present findings imply that the elevation of BP can serve as an endophenotype for a spectrum of hypertensive conditions in pregnancy.

Haplotype-based association of ACE I/D, AT1R 1166A>C, and AGT M235T polymorphisms in renin-angiotensin-aldosterone system genes in Korean women with idiopathic recurrent spontaneous abortions

OBJECTIVES

The objective of this study was to determine whether or not the angiotensin-converting enzyme insertion/deletion (ACE I/D), angiotensin II type 1 receptor (AT1R), and angiotensinogen (AGT) gene polymorphisms are associated with idiopathic recurrent spontaneous abortions (RSAs) in Korean women.

STUDY DESIGN

A total of 251 patients with unexplained consecutive pregnancy losses, and 126 healthy controls with at least one live birth and no history of pregnancy loss.

RESULT

The odds ratios (ORs) of the ACE ID (OR=2.423; 95% confidence interval (CI)=1.417-4.142; p=0.001) and the ACE II (OR=2.050; 95% CI=1.143-3.675; p=0.018) for the ACE DD genotype were significantly different between patients with idiopathic RSA and controls; however, there were no significant differences between patients and controls with respect to the AT1R 1166A>C and AGT M235T polymorphisms. In a haplotype-based analysis of I-A (p=0.010), D-A (p=0.004), I-A-T (p=0.033), D-A-T (p=0.0005), and D-C-T (p=0.013) polymorphism pairs with synergistic effects derived by the MDR method in patients and in controls showed significant results.

CONCLUSION

This study suggests that ACE, AT1R and AGT polymorphisms and haplotypes are a genetic determinant for the risk of idiopathic RSA in Korean women.