Haplotypes of the angiotensin II receptor genes AGTR1 and AGTR2 in women with normotensive pregnancy and women 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.

The effect of AT1R-1166A/C and AT2R-1675A/G polymorphisms on susceptibility to preeclampsia: A systematic review and meta-analysis

BACKGROUND

The aim of this meta-analysis is to investigate the association between Angiotensin II type 1 receptor (AT1R)-1166A/C, Angiotensin II type 2 receptor (AT2R)-1675A/G polymorphisms and susceptibility to preeclampsia (PE).

METHODS

Online databases, including Web of Science, PubMed, EMBASE, CINAHL, CENTRAL, Scopus, Lilacs/SciELO, and Chinese National Knowledge Infrastructure, China Wan Fang, China Science and Technology Journal Database, were used to perform the literature search up to April 2022. The odds ratio (OR) and 95% confidence interval (CI) were used as effect size. The data was analyzed by Stata 15.0 software.

RESULTS

According to the inclusion and exclusion criteria, a total of 22 case-control studies were identified, including 3524 cases and 6308 controls. Our meta-analysis showed that the AT1R -1166 A/C allele was significantly associated with susceptibility to PE (A vs C: OR = 0.82, 95% CI: 0.69-0.96, P = .013), and there was significant difference in recessive gene model (AA vs AC + CC: OR = 0.81, 95% CI: 0.67-0.97, P = .021). However, no association was found between AT2R-1675A/G polymorphism and susceptibility to PE.

CONCLUSION

our meta-analysis suggested that AT1R-1166A/C polymorphism had an association with susceptibility to PE, but AT2R-1675A/G polymorphism had no association with susceptibility to PE.

Analysis of the Epigenome in Multiplex Pre-eclampsia Families Identifies SORD, DGKI, and ICA1 as Novel Candidate Risk Genes

Pre-eclampsia is a serious heritable disorder that affects 5-8% of pregnancies worldwide. While classical genetic studies have identified several susceptibility genes they do not fully explain the heritability of pre-eclampsia. An additional contribution to risk can be quantified by examining the epigenome, in particular the methylome, which is a representation of interactions between environmental and genetic influences on the phenotype. Current array-based epigenetic studies only examine 2-5% of the methylome. Here, we used whole-genome bisulfite sequencing (WGBS) to determine the entire methylome of 13 individuals from two multiplex pre-eclampsia families, comprising one woman with eclampsia, six women with pre-eclampsia, four women with uncomplicated normotensive pregnancies and two male relatives. The analysis of WGBS profiles using two bioinformatics platforms, BSmooth and Bismark, revealed 18,909 differentially methylated CpGs and 4157 differentially methylated regions (DMRs) concordant in females. The methylation patterns support the involvement of previously reported candidate genes, including COL4A1, SLC2A4, PER3, FLT1, GPI, LCT, DDAH1, TGFB3, DLX5, and LRP1B. Statistical analysis of DMRs revealed three novel genes significantly correlated with pre-eclampsia: sorbitol dehydrogenase (SORD, p = 9.98 × 10^-6), diacylglycerol kinase iota (DGKI, p = 2.52 × 10^-5), and islet cell autoantigen 1 (ICA1, 7.54 × 10^-3), demonstrating the potential of WGBS in families for elucidating the role of epigenome in pre-eclampsia and other complex diseases.

Angiotensin II receptor 1 gene variants are associated with high-altitude pulmonary edema risk

Previous studies demonstrated that Angiotensin II Receptor 1 (AGTR1) may play an important role in the development of high-altitude pulmonary edema. We envisaged a role for AGTR1 gene variants in the pathogenesis of HAPE and investigated their potential associations with HAPE in a Han Chinese population. We genotyped seven AGTR1 polymorphisms in 267 patients with diagnosed HAPE and 304 controls and evaluated their association with risk of HAPE. Statistically significant associations were found for the single nucleotide polymorphisms (SNPs) rs275651 (p = 0.017; odds ratio [OR] = 0.65) and rs275652 (p = 0.016; OR = 0.64). Another SNP rs10941679 showed a marginally significant association after adjusting for age and sex in the additive genetic model (adjusted OR = 1.44, 95% CI = 1.01-2.04, p = 0.040). Haplotype analysis confirmed that the haplotype "AG" was associated with a 35% reduction in the risk of developing HAPE, while the haplotype "AA" increased the risk of developing HAPE by 44%. These results provide the first evidence linking genetic variations in AGTR1 with HAPE risk in Han Chinese individuals.

The effects of gene polymorphisms in angiotensin II receptors on pregnancy-induced hypertension and preeclampsia: a systematic review and meta-analysis

BACKGROUND

To assess whether the polymorphisms of angiotensin II type 1 and type 2 receptors (AT1R, AT2R) are associated with pregnancy-induced hypertension (PIH) and preeclampsia.

METHODS

Studies were searched from PubMed, ISI Web of Science and HuGE Navigator.

RESULTS

The A1166C polymorphism of AT1R, A1675G and C3123A polymorphisms of AT2R were analyzed. Significant association was found in recessive model (OR = 1.581, 95% confidence interval (CI): 1.054-2.371) and co-dominant (GG versus AG) model (OR = 1.900, 95%CI: 1.001-3.604) between the A1675G polymorphism and preeclampsia. No association was found between the other polymorphisms and PIH or preeclampsia.

CONCLUSIONS

The A1675G polymorphism might be associated with preeclampsia, but the A1166C and C3123A polymorphisms had no effect on PIH or preeclampsia.

AT2R -1332 G:A polymorphism and its interaction with AT1R 1166 A:C, ACE I/D and MMP-9 -1562 C:T polymorphisms: risk factors for susceptibility to preeclampsia

The possible association of angiotensin type 2 receptor (AT2R) -1332 G:A polymorphism with susceptibility to preeclampsia was studied in 252 women consisted of 155 women with preeclampsia and 97 healthy pregnant women. Also, the interaction of this polymorphism with angiotensin type 1 receptor (AT1R) 1166 A:C, angiotensin converting enzyme insertion/deletion (ACE I/D) and also with matrix metalloproteinase-9 (MMP-9) -1562 C:T polymorphism was investigated. The AT2R -1332 G:A polymorphism was detected using PCR-RFLP method. Significantly higher frequencies of GG+GA genotype and G allele of AT2R were observed in mild (80.2%, p=0.003 and 47.5%, p=0.012, respectively) and severe (77.8%, p=0.034 and 48.1%, p=0.026, respectively) preeclampsia compared to controls (60.8% and 35.1%, respectively). The presence of G allele was associated with 1.69-fold increased risk of preeclampsia (p=0.005). In severe preeclamptic women, systolic and diastolic blood pressures in the presence of GG+GA genotype were significantly higher compared to those in the presence of AA genotype. The concomitant presence of both alleles of AT2R G and AT1R C was associated with 1.3 times increased risk of mild preeclampsia (p=0.03). There was an interaction between AT2R G and ACE D alleles that significantly increased the risk of mild and severe preeclampsia by 1.38- and 1.3-fold, respectively. Also, interaction between MMP-9 T and AT2R G alleles increased the risk of severe preeclampsia 1.39-fold (p=0.028). Our study demonstrated that the G allele of AT2R -1332 G:A polymorphism is associated with an increased risk of preeclampsia. Also, epistatic interaction of G allele and each allele of the AT1R C, ACE D and MMP-9 T was associated with the risk of preeclampsia. Our findings suggest that the renin-angiotensin system (RAS) variants and gene-gene interactions affect the risk of preeclampsia.

Association of maternal AGTR1 polymorphisms and preeclampsia: a systematic review and meta-analysis

OBJECTIVE

Systematic review and meta-analysis to investigate the association between maternal AGTR1 gene single nucleotide polymorphisms (SNPs) and preeclampsia (PE).

METHODS

A systematic literature search was performed using PubMed, EMBASE, Scopus, and HuGE Literature Finder databases. The review was conducted according to PRISMA guidelines. Summary odds ratios (ORs) for the allelic and genotypic contrasts were calculated and compared to indicate the most appropriate genetic model for the polymorphism of interest. Among-study heterogeneity was assessed using the I(2) statistic and publication bias was evaluated visually using funnel plots.

RESULTS

Seven maternal SNPs investigated with PE were found, but only AGTR1 +1166A>C accumulated sufficient evidence for meta-analysis. Summary ORs calculated from eight studies (10 populations involving 845 PE cases and 1150 controls) did not reveal an association between the +1166A>C polymorphism and PE (allelic OR = 1.19, 95% CI: 0.96-1.47). No evidence of publication bias and among-study heterogeneity was detected.

CONCLUSIONS

meta-analysis findings did not support AGTR1 +1166A>C as a susceptibility locus for PE. Other AGTR1 SNPs require more study.

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.

Effects of Angiotensinogen and Angiotensin II Type I Receptor Genes on Blood Pressure and Left Ventricular Mass Trajectories in Multiethnic Youth

The objective of this study was to evaluate the impact of variations of the angiotensinogen (AGT) and angiotensin II type I receptor (AGTR1) genes on progression of blood pressure (BP) and left ventricular mass (LVM) in multiethnic youth. The study was longitudinal involving 581 European American (EA) and African American (AA) youth with 12 assessments over a 15-year period. AGT M235T and three AGTR1 polymorphisms (C-521T, L191L and A1166C) were genotyped and individual growth curve modeling analyses were conducted. Single nucleotide polymorphism (SNP) analyses found a significant 3-way interaction between M235T, ethnicity and gender on BP levels. Systolic BP (SBP) levels were 5.8 mmHg (p = .00003) and diastolic BP (DBP) levels were 2.6 mmHg (p = .005) lower in carriers versus noncarriers of the M235 allele in AA males only. Furthermore, the AGTR1 L191 allele showed a SBP lowering effect in subjects with a high socioeconomic status (SES; p = .048) and a DBP lowering effect in AAs (p = .038). Haplotype analyses identified a protective haplotype (C-521, 191L and A1166) for LVM levels (p = .03). LVM in individuals homozygous for this haplotype was 12.9 g lower than those homozygous for the most common haplotype (–521T, 191L and A1166). No significant interactions were found between the AGT M235T polymorphism and any of the single SNPs or haplotypes of the AGTR1 gene. Our results in multiethnic youth uncover an ethnicity and gender-specific effect of the AGT M235T polymorphism and a SES or ethnicity-specific effect of the AGTR1 L191L polymorphism on the progression of hypertension risk. A protective AGTR1 haplotype for LVM was also identified.

HFE H63D, C282Y and AGTR1 A1166C polymorphisms and brain white matter lesions in the aging brain

Incidental white matter lesions (WML) are a common neuroradiological finding in elderly people and have been linked to dementia and depression. Various mechanisms including hypoxia and increased production of reactive oxygen species (ROS) are implicated in the etiology of WML. The hemochromatosis (HFE) gene p.H63D and p.C282Y polymorphisms have been linked to dysregulation of iron metabolism and increased levels of ROS, whereas Angiotensin II receptor 1 (AGTR1) c.1166A → C polymorphism is known as a vascular risk factor. These genetic polymorphisms were characterized in brains donated to the UK MRC Cognitive Function and Ageing Study (CFAS) to assess their potential role in the risk for development of age-related WML. The study cohort comprised 258 brain donated to CFAS. WML severity was assessed in the postmortem brain donations using magnetic resonance imaging (MRI) scans and scored using the Scheltens' scale. Polymerase chain reaction (PCR) amplification of extracted DNA followed by restriction enzyme digestion was used to genotype the samples. Genotypes were validated using direct sequencing in a smaller sample. The results show that HFE p.H63D polymorphism is not associated with WML severity in the whole cohort. However, there is a significant association of the D allele with severity of WML in noncarriers of the APOE ε4 allele. No association is demonstrated between the HFE p.C282Y nor the AGTR1 c.1166A → C polymorphisms and WML severity. The HFE gene appears to be a genetic risk factor for severe aging WML independently of the APOE ε4 genotype. This would support the role of iron-related oxidative stress, in addition to previously studied factors, e.g., hypoxia as potential risk factors for developing prominent aging WML.

Differential expression of angiotensin II type 1 and type 2 receptors at the maternal–fetal interface: potential roles in early placental development

Angiotensin II (Ang II) is locally generated in the placenta and regulates syncytial transport, vascular contractility and trophoblast invasion. It acts through two receptor subtypes, AGTR1 and AGTR2 (AT1 and AT2), which typically mediate antagonising actions. The objectives of this study are to characterise the cellular distribution of AGTR1 and AGTR2 at the maternal–fetal interface and explore the effects on cytotrophoblast turnover. Low levels ofAGTR2mRNA were detected in first trimester placental homogenates using real-time PCR. Immunohistochemistry using polyclonal antibodies against AGTR1 and AGTR2 detected the receptors in first trimester placenta, decidua basalis and villous tip outgrowths in culture. Serial staining with cytokeratin-7 was used to identify extravillous trophoblasts (EVTs). AGTR1 was found in the syncytiotrophoblast microvillous membrane, in a subpopulation of villous cytotrophoblasts, and in Hofbauer cells. AGTR1 was strongly upregulated in cytotrophoblasts in cell columns and villous tip outgrowths, but was absent in interstitial and endovascular EVTs within the decidua. AGTR2 immunostaining was present in Hofbauer cells and villous cytotrophoblasts, but was absent from syncytiotrophoblast. Faint staining was detected in cell column cytotrophoblasts and villous outgrowths, but not in EVTs within the decidua. Both receptors were detected in placental homogenates by western blotting. Ang II significantly increased proliferation of cytotrophoblasts in both villous explants and villous tip outgrowths, but did not affect apoptosis. Blockade of AGTR1 and AGTR2 together abrogated this effect. This study shows specific expression patterns for AGTR1 and AGTR2 in distinct trophoblast populations at the maternal–fetal interface and suggests that Ang II plays a role in placental development and generation of EVTs.

Angiotensin II type 2 receptor gene polymorphisms in cardiovascular disease

Considerable progress in our understanding of the role of the angiotensin II type 2 (AT(2)) receptor in the development of cardiac hypertrophy and coronary artery disease has been achieved using in vitro and in vivo animal models. Our understanding in humans, however, has been hindered by the lack of availability of specific AT(2) receptor agonists and antagonists suitable for human study. Nevertheless, an alternative approach involving genotyping humans for a functional polymorphism within the AT(2) receptor gene (-1332G/A) has been used in several association studies to elucidate the pathogenic role of the AT(2) receptor in cardiovascular disease. Both the A allele and the G allele have independently been associated with left ventricular remodelling. However, the methods of measuring left ventricular mass, sodium balance, age and degree of remodelling appear to influence the outcome. An association of carriers of the G allele and premature coronary artery disease has also been established, particularly in males presenting with stenotic atherosclerosis requiring revascularisation. At the molecular level, it remains unclear as to whether carriers of the G allele express more or fewer AT(2) receptors when compared to carriers of the A allele. Consequently, it is presently not possible to definitively interpret the role of the AT(2) receptor in human cardiovascular disease from these association studies.

Genotype distribution of estrogen receptor alpha polymorphisms in pregnant women from healthy and preeclampsia populations and its relation to blood pressure levels

BACKGROUND

The estrogen receptor alpha gene (ESR1) seems to be a potential candidate in altering risk for preeclampsia due to important estrogenic biological effects. Despite its previously reported association with severe preeclampsia in combined genotype in one selected ethnic group, further studies in other populations are required. The objective of this study was to investigate the relationship of the gene polymorphisms of the estrogen receptor alpha with preeclampsia in a southwest Chinese population.

METHODS

We genotyped two polymorphisms in the ESR1 gene (PvuII and XbaI) by polymerase chain reaction-restriction fragment length polymorphism analysis in a Chinese population.

RESULTS

In the case-control study which included 204 preeclampsia case subjects and 236 normal control subjects, the frequencies of allele T for the PvuII site and allele G for the XbaI site in the patients (41.67% and 23.53%, respectively) were similar to those observed in controls (43.01% and 19.70%, respectively). Furthermore, the combined genotype analysis of ESR1 PvuII and XbaI polymorphisms showed no increased risk of either severe or total preeclampsia in our study populations. However, it showed that the CC homozygotes and CT heterozygotes in control pregnant women had higher systolic blood pressure levels than TT homozygotes for the PvuII site after adjustment for age and body mass index (p<0.05).

CONCLUSIONS

Our work does not provide evidence in favor of ESR1 PvuII and XbaI being associated with preeclampsia but with increased blood pressure levels in normal pregnant women, in a southwest Chinese population.

The relationship between the plasma concentration of irbesartan and the antihypertensive response is disclosed by an angiotensin II type 1 receptor polymorphism: results from the Swedish Irbesartan Left Ventricular Hypertrophy Investigation vs. Atenolol (SILVHIA) Trial

BACKGROUND

The aim of this study was to investigate the effect of the plasma concentration of irbesartan, a specific angiotensin II type 1 receptor (AT1R) antagonist, and the blood pressure response in relation to AT1R gene polymorphisms.

METHODS

Plasma irbesartan was analyzed in 42 patients with mild-to-moderate hypertension and left ventricular hypertrophy from the Swedish Irbesartan Left Ventricular Hypertrophy Investigation vs. Atenolol (SILVHIA) trial, who were treated with irbesartan as monotherapy for 12 weeks. Blood pressure and irbesartan concentration were measured at trough, i.e., 24 +/- 3 h after the last dose. Five AT1R gene polymorphisms were analyzed by minisequencing.

RESULTS

Neither the plasma concentration of irbesartan, nor any of the AT1R polymorphisms were associated with the blood pressure response to irbesartan treatment. However, the interaction term between the plasma concentration of irbesartan and the AT1R C5245T polymorphism was related to the reduction in systolic blood pressure after 12 weeks of treatment (P = 0.025). Furthermore, the plasma concentration of irbesartan was related to the change in systolic blood pressure in individuals homozygous for the AT1R 5245 T allele (r = -0.56, P = 0.030), but not for other genotypes.

CONCLUSIONS

There was an association between plasma concentrations of irbesartan and the blood pressure response for hypertensive patients with AT1R 5245 TT. Because of the small sample size, this study needs to be viewed as hypothesis generating. This is the first study, to our knowledge, indicating that the concentration-response relationship of an antihypertensive drug may be genotype dependent.

Genes and the preeclampsia syndrome

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

Candidate-gene association study of mothers with pre-eclampsia, and their infants, analyzing 775 SNPs in 190 genes

Pre-eclampsia (PE) affects 5-7% of pregnancies in the US, and is a leading cause of maternal death and perinatal morbidity and mortality worldwide. To identify genes with a role in PE, we conducted a large-scale association study evaluating 775 SNPs in 190 candidate genes selected for a potential role in obstetrical complications. SNP discovery was performed by DNA sequencing, and genotyping was carried out in a high-throughput facility using the MassARRAY(TM) System. Women with PE (n = 394) and their offspring (n = 324) were compared with control women (n = 602) and their offspring (n = 631) from the same hospital-based population. Haplotypes were estimated for each gene using the EM algorithm, and empirical p values were obtained for a logistic regression-based score test, adjusted for significant covariates. An interaction model between maternal and offspring genotypes was also evaluated. The most significant findings for association with PE were COL1A1 (p = 0.0011) and IL1A (p = 0.0014) for the maternal genotype, and PLAUR (p = 0.0008) for the offspring genotype. Common candidate genes for PE, including MTHFR and NOS3, were not significantly associated with PE. For the interaction model, SNPs within IGF1 (p = 0.0035) and IL4R (p = 0.0036) gave the most significant results. This study is one of the most comprehensive genetic association studies of PE to date, including an evaluation of offspring genotypes that have rarely been considered in previous studies. Although we did not identify statistically significant evidence of association for any of the candidate loci evaluated here after adjusting for multiple testing using the false discovery rate, additional compelling evidence exists, including multiple SNPs with nominally significant p values in COL1A1 and the IL1A region, and previous reports of association for IL1A, to support continued interest in these genes as candidates for PE. Identification of the genetic regulators of PE may have broader implications, since women with PE are at increased risk of death from cardiovascular diseases later in life.

Searching for genetic clues to the causes of pre-eclampsia

Pre-eclampsia and its related syndromes are significant causes of maternal and fetal death, but much remains unclear about the underlying disease mechanisms. Epidemiological research has consistently demonstrated a familial predisposition to pre-eclampsia, which has encouraged genetic research in this area. The goal is the discovery of susceptibility genes which will inform understanding of the pathophysiology of pre-eclampsia, and may prove to be targets for therapeutic or preventative strategies. This review examines the application of molecular technologies to the search for genetic clues in pre-eclampsia and emphasizes the importance of integrative approaches. The results of recent genome-wide linkage studies have been particularly encouraging, identifying a number of loci which merit closer examination. Candidate gene studies have proved less fruitful, generating conflicting and inconclusive results. Possible explanations and remedies for this deficiency are discussed with a view to stimulating closer collaboration between researchers in this field.

Altered transmission of maternal angiotensin II receptor haplotypes in fetal growth restriction

Fetal growth restriction (FGR) predisposes to significant short- and long-term health problems. Epidemiological studies have suggested a role for inherited factors in its pathogenesis. The angiotensin II receptor genes, AGTR1 and AGTR2, are candidate genes because they mediate processes that are important for placentation. This study investigated AGTR1 and AGTR2 haplotypes and genotypes in FGR. A total of 107 families (father, mother, and baby) with FGR, and 101 families with normal pregnancies were genotyped at five sites in AGTR1 and six sites across AGTR2. All of the participants were white western Europeans. FGR was identified antenatally by ultrasound scans and confirmed postnatally by correcting the birth weight centile for gestation, infant sex, maternal height, weight, and parity. Fetal genes were investigated using transmission disequilibrium testing (TDT), and a case-control comparison of maternal haplotypes was conducted. FGR was associated with maternal (but not paternal) transmission of the AGTR1 haplotype (GenBank AF245699.1) g.4955T, g.5052T, g.5245C, g.5612A, and haplotype g.4955T, g.5052T, g.5245T, g.5612A. Haplotype g.4955A, g.5052G, g.5245T, g.5612G was undertransmitted (P = 0.002). TDT of the AGTR1 genotype showed undertransmission of maternal AGTR1 genotypes g.4955T>A (odds ratio (OR), 0.34 (95% confidence interval (CI), 0.14-0.86); P = 0.02), g.5052T>G (OR, 0.18 (0.06-0.48); P<0.001), and g.5612A>G (OR, 0.21 (0.08-0.55); P < 0.001) in FGR. There were no differences in maternal haplotype frequencies between normal pregnancy and FGR for AGTR1 or AGTR2 (P > 0.10). This is the first study to show distortion of transmission of maternal AGTR1 haplotypes in FGR, which suggests that this gene plays a role in FGR. In particular, maternal-fetal gene sharing may be an important factor.

Transforming growth factor beta1 regulates angiotensin II type I receptor gene expression in the extravillous trophoblast cell line SGHPL-4

The angiotensin II type 1 (AT1) receptor, transforming growth factor beta1 (TGFbeta1) and Oncostatin M (OSM) control key pathways that may be important during placentation. Although interactions between them exist in other tissues, trophoblast cells have not been investigated. Extravillous trophoblast cells, SGHPL-4, were stimulated with 10 ng/ml TGFbeta1 +/- 100 ng/ml OSM for 24 h. Real-time PCR showed that AT1 expression increased 2.76-fold [95% confidence interval (CI) = 1-6.74, P = 0.05] in response to TGFbeta1 and 4.21-fold (95% CI = 1.33-11.76, P = 0.03) with TGFbeta1 + OSM. Luciferase reporter gene constructs containing three haplotypes of the 59 flanking region of the AT1 receptor gene were transfected into SGHPL-4 and HepG2 cells and stimulated with 0.1, 1 and 10 ng/ml TGFbeta1 and 50 ng/ml OSM. Responses were dose and cell dependent. Luciferase activity increased in HepG2 cells in response to TGFbeta1 alone or together with OSM (P < 0.001); transcriptional activation differed between AT1 receptor gene haplotypes. In SGHPL-4 cells, luciferase activity was reduced on exposure to low concentrations of TGFbeta1 or high concentrations of TGFbeta1 combined with OSM (P = 0.003); the response was unaffected by haplotype. Interaction between AT1 and TGFbeta1 is a novel observation in trophoblast and suggests new avenues for the study of placentation.

Disentangling fetal and maternal susceptibility for pre-eclampsia: a British multicenter candidate-gene study

The Genetics of Pre-Eclampsia (GOPEC) collaboration aims to identify genetic factors in U.K. families affected by pre-eclampsia. A number of genetic studies have reported associations with pre-eclampsia, but attempts to replicate these findings have yielded inconsistent results. We describe the results of extensive genotyping of seven candidate genes previously reported as conferring susceptibility to pre-eclampsia. Six hundred fifty-seven women affected by pre-eclampsia and their families were genotyped at 28 single-nucleotide polymorphisms in the genes encoding angiotensinogen, the angiotensin receptors, factor V Leiden variant, methylene tetrahydrofolate reductase, nitric oxide synthase, and TNFalpha. Genotypes were analyzed by the transmission/disequilibrium test. Genotype risk ratios (GRRs) associated with maternal genotypes had a range of 0.70-1.16; GRRs associated with fetal genotypes had a range of 0.72-1.11. No GRR achieved the prespecified criteria for statistical significance (posterior probability >.05). We conclude that none of the genetic variants tested in this large study of strictly defined pre-eclamptic pregnancies confers a high risk of disease. The results emphasize the importance of conducting rigorously designed studies of adequate size to provide precise genetic risks with narrow confidence intervals, if overreporting of false-positive results is to be avoided.

Polymorphism in angiotensin II receptor genes and hypertension

Molecular variants of individual components of the renin-angiotensin system (RAS) have been thought to contribute to an inherited predisposition towards essential hypertension. The angiotensin II type 1 receptor (AT-1) mediates the major pressor and trophic actions of angiotensin II (Ang II) and at least 50 different polymorphisms have been described in the AT-1 gene (AT(1)R gene); in particular, the C allele of the +1166A/C polymorphism has been associated with the severe form of essential hypertension, but the role of this polymorphism is still ambiguous in pathologies related to high Ang II levels, such as deterioration of renal function, arterial stiffness and hypertrophic cardiomyopathy. A relationship was suggested between AT 1R A1166C polymorphism and the humoral and renal haemodynamic responses to losartan, an AT-1 blocker, as well as with enhanced Ang II vascular reactivity or sensitivity. Polymorphism has also been described in angiotensin II type 2 receptor (AT-2) gene, AT-2 being the mediator for vasodilatation, natriuresis and apoptosis of smooth muscle cells; associations were found between some of these polymorphisms and both hypertension and left ventricular structure. Further evaluation in adequately powered studies is necessary for full assessment of the allelic markers in genes for RAS components, as well as to allow determination of a predisposition to hypertension or related diseases and selection of an appropriate antihypertensive drug for an individual.