Associations of polymorphisms of the angiotensinogen M235 polymorphism and angiotensin-converting-enzyme intron 16 insertion/deletion polymorphism with preeclampsia in Korean women

Second Trimester Amniotic Fluid Angiotensinogen Levels Linked to Increased Fetal Birth Weight and Shorter Gestational Age in Term Pregnancies

BACKGROUND

Despite the considerable progress made in recent years in fetal assessment, the etiology of fetal growth disturbances is not as yet well understood. In an effort to enhance our knowledge in this area, we investigated the associations of the amniotic fluid angiotensinogen of the renin-angiotensin system with fetal growth abnormalities.

METHODS

We collected amniotic fluid samples from 70 pregnant women who underwent amniocentesis during their early second trimester. Birth weight was documented upon delivery, after which the embryos corresponding to the respective amniotic fluid samples were categorized into three groups as follows: small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). Amniotic fluid angiotensinogen levels were determined by using ELISA kits.

RESULTS

Mean angiotensinogen values were 3885 ng/mL (range: 1625-5375 ng/mL), 4885 ng/mL (range: 1580-8460 ng/mL), and 4670 ng/mL (range: 1995-7250 ng/mL) in the SGA, LGA, and AGA fetuses, respectively. The concentrations in the three groups were not statistically significantly different. Although there were wide discrepancies between the mean values of the subgroups, the large confidence intervals in the three groups negatively affected the statistical analysis. However, multiple regression analysis revealed a statistically significant negative correlation between the angiotensinogen levels and gestational age and a statistically significant positive correlation between the birth weight and angiotensinogen levels.

DISCUSSION

Our findings suggest that fetal growth abnormalities did not correlate with differences in the amniotic fluid levels of angiotensinogen in early second trimester pregnancies. However, increased angiotensinogen levels were found to be consistent with a smaller gestational age at birth and increased BMI of neonates.

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.

Pre-Existing Diabetes Mellitus, Hypertension and KidneyDisease as Risk Factors of Pre-Eclampsia: A Disease of Theories and Its Association with Genetic Polymorphism

Pre-existing diabetes, hypertension and kidney disorders are prominent risk factors of pre-eclampsia (PE). It is a multifactorial pregnancy disorder associated with high blood pressure, proteinuria, and multiorgan failure, which develops after the 20th week of pregnancy. It is one of the most feared pregnancy disorders, as it consumes thousands of fetomaternal lives per annum. According to clinical and pathological studies, the placenta appears to be a key player in the pathogenesis of PE; however, the exact origin of this disorder is still under debate. Defective placentation and angiogenesis are the hallmarks of PE progression. This angiogenic imbalance, together with maternal susceptibility, might determine the severity and clinical presentation of PE. This article comprehensively examines the mechanisms of pathogenesis of PE and current evidence of the factors involved in its progression. Finally, this article will explore the genetic association of PE, various candidate genes, their proposed mechanisms and variants involved in its pathogenesis.

The Prevalence Of Specific Gene Polymorphisms Related To Thrombophilia In Egyptian Women With Recurrent Pregnancy Loss

Background:

Despite the enhanced progress in identifying a number of leading causes to fetal miscarriage, still some women suffer from recurrent pregnancy loss (RPL) for unknown cause. A hidden genetic influence of coexisting hereditary thrombophilia was assumed to have a role.

Aim:

The aim was to investigate the association between unexplained RPL and thrombophilic gene variants of angiotensin I-converting enzyme (ACE) (rs4646994) and β-fibrinogen (rs1800790) genes.

Settings and Design:

The present case–control study was conducted on unexplained RPL in eighty women and eighty matched controls with no history of previous pregnancy loss.

Materials and Methods:

Analysis of extracted DNA was performed using polymerase chain reaction-restriction fragment length polymorphism method.

Statistical Analysis:

The frequency of genotypes and alleles was compared between groups using Chi-square test or Fisher's exact test. Risk assessment was made by odds ratio (OR) at a 95% confidence interval (CI).

Results:

Women with RPL group had higher frequency of DD than controls (47.5%, 31.25%, respectively, P = 0.086). D allele frequency was 0.67 and 0.54 in the control (P = 0.022). D allele carriers were at higher risk of RPL than the control as OR was 1.694 at 95% CI from 1.08 to 2.67. There was no association between the rs1800790 variant of β-fibrinogen gene and RPL.

Conclusion:

Females who are carriers for D allele of ACE I/D gene polymorphism are more liable to suffer from RPL. Screening for hereditary thrombophilia in females who are planning to conceive and have a history of RPL of unidentified cause is of great value to provide proper management and genetic counseling to high-risk couples.

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.

I/D Polymorphism Gene ACE and Risk of Preeclampsia in Women with Gestational Diabetes Mellitus

Preeclampsia (PE) and gestational diabetes mellitus (GDM) are the most common complications of pregnancy, which result in adverse outcomes for the mother and the fetus. GDM is regarded as a separate independent risk factor for PE development, as evidenced by a higher preeclampsia rate in gestational diabetes mellitus than in the general population. The role the endothelial cell dysfunction plays is considered to be the most reasonable one in the origin of these diseases. The activity of plasma and tissue angiotensin converting enzyme (ACE) is believed to be genetically controlled. The available data suggests that increased ACE activity due to deletion (D)/insertion (I) in the 16th intron of ACE gene, which is called ACE gene I/D polymorphism, is associated with preeclampsia and varies depending on the studied population and the geography. We did not find any literature data that estimates the influence of ACE gene I/D polymorphism on PE rate in pregnant women with GDM. Therefore, the present study aimed to investigate a relationship between ACE gene I/D polymorphism and preeclampsia development in the case of GDM in the Russian population. The study used the genomic DNA derived by phenol-chloroform extraction method from venous blood samples in 137 pregnant women, including samples of 74 women with GDM accompanied with PE and the blood samples of 63 women with GDM w/o preeclampsia. Genotyping of insertion/deletion in the I/D region (16 intron of АСЕ gene) was conducted by real-time PCR using the TaqMan competing probe technology. The particular features in the frequency array of alleles and genotypes of the ACE gen I/D polymorphism under review, as associated with preeclampsia development risk in pregnant women with GDM, were identified. The acquired data testify to the need to further study of ACE gene I/D region polymorphism association in a large patient sample taking into account the PE and GDM risk factors estimated in the clinical practice.

Assessment of angiotensin converting enzyme gene polymorphism in preeclampsia mothers of Bangladesh

The study aimed to assess the association of ACE insertion/deletion (I/D) polymorphisms with the susceptibility for preeclampsia in Bangladesh. It was a case-control study involving 220 subjects (100 preeclamptic and 120 normal pregnant women). The ACE (I/D) genotyping was done using the conventional PCR method. Overall, the frequency of ACE II genotypes was significantly (p<.05) higher in normal pregnant women than the preeclamptic women. The pregnant mother with DD genotype was at 3.43-fold higher risk (OR = 3.43; p<.01) of developing preeclampsia while pregnant mother with ID genotype was at lower risk (OR = 1.32; p>.05). On the other hand, patients having either DD or ID genotypes showed 1.9 fold (OR = 1.90; p>.05) increased risk of developing preeclampsia compared to the control group but not statistically significant. This study suggested that ACE (DD) genotypes may have strong associations with the occurrence of preeclampsia.Impact StatementWhat is already known on this subject? The study was conducted among 100 preeclamptic and 120 normal pregnant women. The preeclamptic patients were diagnosed by protein in urine and high blood pressure. The normal pregnant women were selected with no known complications.What the results of this study add? Overall, the pregnant mothers with DD genotype were at 3.43-fold higher risk of developing preeclampsia while pregnant mothers with ID or II genotypes were at a lower risk.What the implications are of these findings for clinical practice and/or further research? ACE (I/D) gene would be a biomarker of early diagnosis of preeclampsia and also be helpful to intervene in personalised medicine and gene therapy as a novel treatment of preeclampsia.

Three polymorphisms of renin-angiotensin system and preeclampsia risk

Purpose

Some data suggest an association between the single nucleotide polymorphisms AGT T704C, ACE I/D, and AT1R A1166C and preeclampsia, but overall, the data are conflicting; the aim of our study was to discover a more stable and reliable association between these polymorphisms and PE risk.

Methods

A comprehensive literature search for this meta-analysis was conducted. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated to evaluate the strength, and heterogeneity test was conducted. Trial sequential analysis was also performed.

Results

A total of forty studies were finally included in our meta-analysis. The AGT T704C polymorphism was associated with PE risk in three genetic models (dominant OR = 1.33, 95%CI = 1.12–1.59; heterozygote OR = 1.26, 95%CI = 1.05–1.52; homozygote OR = 1.44, 95%CI = 1.14–1.83). No heterogeneity was observed in the three genetic models for the ACE I/D polymorphism. For subgroup analysis by geography, no significant association was detected. Significant associations were observed in mixed race, early-onset, late-onset, and more than 200 subgroups for the AT1R A1166C polymorphism; however, only one study was analyzed in these subgroups.

Conclusions

Our results indicated the AGT T704C and ACE I/D polymorphisms were associated with an increased risk of PE. Increased risks were also observed for the two polymorphisms in subgroups including Asians, Europeans, Caucasoid, and Mongoloid. Moreover, an increased PE risk with the ACE I/D polymorphism in the severe PE population was also detected. Regarding the AT1R A1166C polymorphism, weak associations were observed, but further studies are required.

Electronic supplementary material

The online version of this article (10.1007/s10815-020-01971-8) contains supplementary material, which is available to authorized users.

The Role of the Renin-Angiotensin-Aldosterone System in Preeclampsia: a Review

PURPOSE OF REVIEW

Preeclampsia (PE) is a complex human pregnancy-specific condition and is clinically characterized by new onset hypertension and proteinuria in the second half of pregnancy. The precise etiology of PE is unknown, but much of the pathophysiology has been elucidated, and it is accepted that the disorder is multifactorial in nature. Historically, because of the presence of proteinuria, the role of the renin-angiotensin-aldosterone system (RAAS) has been considered in the etiology of PE. However, the results of studies (including maternal circulatory angiotensin II, urinary angiotensinogen, plasma renin and prorenin, AT1 receptor antibodies, and gene polymorphisms) on the role of the RAAS in the etiology of PE have proved controversial. The purpose of this narrative review was to evaluate the contemporary literature on the RAAS and its role in the pathophysiology of pregnancy.

RECENT FINDINGS

The current review shows that although the RAAS has a role in the development of normal pregnancy, it does not have a significant role in the pathophysiology of PE except for the AT1-AA components. Despite many researchers having measured increases in s[P}RR and [P]RR, this may be independent of the RAAS. Our view is in keeping with contemporary thinking that the placenta rather than the RAAS plays a central role in elaborating pro-inflammatory factors (antiangiogenic and angiogenic) into the maternal circulation resulting in widespread endothelial dysfunction in all organ systems including the renal system.

Meta-analysis of angiotensin-converting enzyme insersion/delection polymorphism and pre-eclampsia susceptibility

AIM

In recent years, there were many studies on angiotensin-converting enzyme insersion/delection (ACE I/D) polymorphism and pre-eclampsia susceptibility, but the conclusion was still inconclusive. Our study is to explore the relationship between the ACE I/D polymorphism and the risk of pre-eclampsia.

METHODS

The literature on the relationship between ACE I/D gene polymorphism and Pre-eclampsia susceptibility was obtained by searching the databases of Wanfang, VIP, Medline, CNKI, Embase, Pubmed and Springerlink, which was published from the establishment of the databases to October 2019. Taking the odds ratio (OR) value and its 95% confidence interval (CI) as the effect size, the Meta-analysis was carried out by using stata 15.0 software.

RESULTS

Thirty articles, consisting of 3184 patients and 3912 controls, were included. The results showed that allele D was compared with allele I, with the OR value of 1.29 (95% CI: 1.12 ~ 1.50, P < 0.05). Subgroup analysis showed that in Caucasians, allele D was associated with OR of 1.28 (95% CI: 1.08 ~ 1.53, P < 0.05). There was no significant difference in Asians. There was statistical significance in recessive gene model and homozygous gene model, as well as in that of Asian and Caucasian. In homozygous model, there was statistical significance, but subgroup analysis showed there was no statistical significance in Asian and Caucasian. There was no statistical significance in dominant model and heterozygous model.

CONCLUSION

The polymorphism of ACE I/D gene was associated with the risk of pre-eclampsia. Allele D and genotype DD may increase the risk of Pre-eclampsia in pregnant women.

Association study of M235T and A-6G polymorphisms in angiotensinogen gene with risk of developing preeclampsia in Iranian population

OBJECTIVE

Preeclampsia (PE) is a life-threatening complication of pregnancy that accounts for 12% of all maternal deaths worldwide. The aim of this study is to investigate the relationships between the polymorphisms of angiotensinogen (AGT) gene and preeclampsia.

MATERIAL AND METHODS

In this study, 240 unrelated preeclampsia patients and 178 normotensive women were examined. Genomic DNA was extracted then we assessed M235T(C/T) and A-6G polymorphisms of the AGT gene. Genotyping of M235T and A-6G polymorphisms were performed using SSP-PCR and MS-PCR, respectively.

RESULTS

A significant protective association was observed between A-6G G allele, A-6G A/G heterozygote genotype (OR = 0.6, p = 0.007 and OR = 0.6, p = 0.04) against PE. Furthermore, it was shown that two copies of A-6G A allele would increase PE risk (OR: 0.62, p = 0.04). Our results did not show a significant association for M235T polymorphism and PE. However, the combinations of A-6G A/A genotype and M235T T/C genotype (OR = 0.4, p = 0.02) and also A-6G A/G genotype and M235T T/C genotype (OR = 0.5, p = 0.04) in controls represented a significant protective association against PE.

CONCLUSION

According to the existence of significant correlation between two candidate polymorphisms, A-6G and M235T polymorphisms, with PE disease in our study, they may be considered as valuable factors in susceptibility to PE disease in Iranian women.

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.

Lack of Association between Angiotensin Converting Enzyme I/D Polymorphism and Unexplained Recurrent Miscarriage in Saudi Arabia

BACKGROUND

An insertion/deletion (I/D) polymorphism in the angiotensin converting enzyme (ACE) gene has been associated with recurrent miscarriage (RM) in several populations. We initiated this study to determine the association, if any, between the I/D polymorphism of ACE gene and RM in Saudi females.

METHOD

This study was conducted on 61 Saudi females suffering from RM (mean age: 34.1±6.2 years; range 15-45) attending clinics at King Khalid University Hospital, and 59 age matched females who had at least 2 children, as controls. Blood samples were drawn in EDTA tubes by venipuncture. DNA was extracted using the Puregene DNA purification kits. Insertion/Deletion (I/D) polymorphism of ACE gene was investigated by amplifying the genomic DNA by PCR using gene-specific primers. A single 190 bp or 490 bp band was obtained in the homozygous cases for the D allele or I allele, respectively, while the presence of both 190 and 490 bp bands indicated heterozygosity (ID).

STATISTICAL ANALYSIS

Deviation from Hardy-Weinberg equilibrium was determined (http://ihg.gsf.de/cgi-bin/hw/hwa1.pl). A standard chi-square (χ²) test was used for comparing the genotype and allele frequencies in the two groups and Students't' test and χ² test were employed to compare values between the two groups. P<0.05 was considered statistically significant.

RESULTS

The frequencies of DD, ID, and II genotypes were 56.7%, 29.5% and 4.9%, respectively, in females with RM and 54.2%, 42.3% and 3.3% respectively in the control group, but the difference was not statistically significant.

CONCLUSION

In some populations, meta-analyses showed an association between I/D polymorphism and RM risk, and the D allele was implicated as an increased risk factor for RM. However, this association was not apparent in the Saudi females.

Association of angiotensinogen gene polymorphisms and angiogenic factors with preeclampsia in Chinese women

OBJECTIVE

To investigate the association of angiotensinogen (AGT) gene polymorphisms and angiogenic factors with preeclampsia (PE) in Chinese women.

METHODS

A study on Chinese women was performed. Detection of the M235T polymorphism of AGT gene was carried out by PCR. Using a χ² test, genotype and allele frequencies were compared in all groups. Maternal serum levels of vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) and soluble fms-like tyrosine kinase 1 (sFlt1) at gestation were compared between 92 women with PE and 100 controls by ELISA.

RESULTS

Compared to the controls, the AGT homozygous of TT genotype in PE occurred significantly more frequently and the T allele was observed to occur more frequently than the M allele (p < 0.05). sFlt1 was present in high quantities in the serum of women with PE and was associated with low levels of free VEGF and PlGF (p < 0.05). Plasma sFlt1 levels are higher in PE patients with TT heterozygotes compared with MM homozygotes, but PIGF is lower (p < 0.05). Plasma VEGF concentrations showed no significant difference.

CONCLUSIONS

Our study showed that AGT M235T polymorphism is associated with PE in Chinese women. Furthermore, the gene polymorphism of the components of the renin-angiotensin system may contribute to the concentration alterations of sFlt1, VEGF, and PlGF in maternal serum, which causes disordered vasculogenesis contributing to PE.

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.

Interleukin-1β gene is not associated with preeclampsia in Taiwanese

OBJECTIVE

To identify associations between the interleukin-1β gene and preeclampsia in Taiwanese women.

METHODS AND MATERIALS

We genotyped Taiwanese population (102 women with preeclampsia and 148 controls) for two polymorphisms of the interleukin-1β gene (promoter region and Exon 5) by using polymerase chain reaction and restriction fragment length polymorphism analysis. The association between the genotype and disease was examined by Chi-square tests.

RESULTS

We found no association between the two polymorphic sites of interleukin-1β gene and preeclampsia. No significant differences were detected in genotype distributions and allele frequencies of the AvaI polymorphism at position -511 in the promoter region and the TaqI polymorphism at position +3953 within Exon 5.

CONCLUSION

Our data do not support a role of the interleukin-1β gene in the pathogenesis of preeclampsia in Taiwanese women.

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.

Preeclampsia and angiotensin converting enzyme (ACE) I/D and angiotensin II type-1 receptor (AT1R) A1166C polymorphisms: association with ACE I/D polymorphism

BACKGROUND

The aim of the present study was to investigate the association between angiotensin converting enzyme (ACE) insertion/deletion (I/D) and angiotensin II type-1 receptor (AT1R) A1166C polymorphisms with the risk of preeclampsia and lipid peroxidation in preeclamptic women from Western Iran.

METHODS

One hundred and ninety-eight preeclamptic women (128 women with mild and 70 with severe forms) and 100 age- and parity-matched controls were enrolled in this case-control study.

RESULTS

The presence of D allele of ACE was associated with a 1.8-fold increased risk of preeclampsia (p=0.002) in total preeclamptic patients. The frequency of AT1R AC+CC genotypes was higher in mild preeclamptic women (32%) compared to controls (27.2%) (p>0.05). In mild preeclamptic women with ID genotype, the level of total antioxidant capacity (TAC) was significantly decreased compared to those with II genotype. Also, there was a trend toward increasing malondialdehyde (MDA) and decreasing TAC levels in mild and severe preeclamptic women with AT1R AA through CC genotypes.

CONCLUSIONS

Our study indicates that lipid peroxidation and oxidative stress are involved in the development of preeclampsia that might be influenced by polymorphism in the renin-angiotensin-aldosterone system genes.

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.

Angiotensin converting enzyme insertion/deletion polymorphism and risk of pregnancy hypertensive disorders: a meta-analysis

BACKGROUND

The angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism has been reported inconsistently as being associated with risk of pregnancy hypertensive disorders (PHDs). We examined these associations by performing a meta-analysis.

METHODS

Two investigators independently consulted the Medline, Embase, CNKI, and Chinese Biomedicine databases. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated in fixed- and random-effects models when appropriate. Subgroup analyses were performed by ethnicity, types of PHD (gestational hypertension, pre-eclampsia and eclampsia), country and Hardy-Weinberg equilibrium (HWE) in controls.

RESULTS

This meta-analysis included 30 case-control studies with 3523 cases and 4817 controls. Overall, we found that the DD variant of the ACE I/D polymorphism was associated with a significantly increased PHD risk. In the subgroup analysis by ethnicity, the results suggested that the DD genotype was significantly associated with risk of PHD development among Asians and Caucasians. Moreover, when stratifying by types of PHD, a significantly increased risk was observed for pre-eclampsia. Interestingly, when stratifying by country, a significantly elevated risk was found among 'others' countries (those that were not China or Korea). Limiting the analysis to the studies within HWE, the results were persistent and robust.

CONCLUSION

This meta-analysis suggests that the I/D polymorphism of ACE may be associated with PHD risk, especially among Asians and Caucasians.

Association of angiotensin-converting enzyme intron 16 insertion/deletion and angiotensin II type 1 receptor A1166C gene polymorphisms with preeclampsia in South East of Iran

Some evidence suggests that a variety of genetic factors contributed in pathogenesis of the preeclampsia. The aim of this study was to assess the association between the angiotensin-converting enzyme (ACE) I/D and angiotensin II type1 receptor A1166C polymorphisms with preeclampsia. This study was performed in 125 preeclamptic pregnant women and 132 controls. The I/D Polymorphism of the ACE gene was assessed by polymerase chain reaction and the A1166C Polymorphism of the AT1R gene was determined by restriction fragment length polymorphism. The genotype and allele frequencies of I/D polymorphism differed between two groups. The risk of preeclampsia was 3.2-fold in pregnant women with D allele (OR, 3.2 [95% CI, 1.1 to 3.8]; P = 0.01). The distribution of the AT1R gene A1166C polymorphism was similar in affected and control groups. Our results supported that presence of the I/D polymorphism of ACE gene is a marker for the increased risk of preeclampsia.

Preeclampsia in North Indian women: the contribution of genetic polymorphisms

AIM

To find association of angiotensin-converting enzyme (ACE) insertion/deletion (I/D), angiotensinogen (AGT) T704C, methylenetetrahydrofolate reductase (MTHFR) C677T and factor V Leiden (FVL) G1691A polymorphisms with pre-eclampsia (PE) in North Indian women.

MATERIAL & METHODS

In this prospective case-control study, genotyping of 200 pre-eclamptic women and 200 normotensive pregnant controls was performed for the ACE I/D, AGT T/C,MTHFR C/T and FVL G/A polymorphisms. Statistical analysis was carried out using SPSS and Epi Info to estimate their association with PE. The association of these polymorphisms with nonsevere PE and severe PE was separately assessed.

RESULTS

The FVL mutation was found in 4% of women and increased the risk of PE twofold (odds ratio [OR] 2.08, P-value 0.03). The MTHFR mutant allele was found to be protective (OR 0.59, P-value 0.01). Both these polymorphisms showed similar association with nonsevere PE (OR 2.149, P-value 0.038 and OR 0.565, P-value 0.222, respectively) but not with severe PE. The ACE I/D and AGT T/C polymorphisms were not found to be associated with PE overall (OR 1.26, P-value 0.11 and OR 1.15, P-value 0.35, respectively), but ACE I/D polymorphism was found to increase the risk of severe PE (OR 1.53, P-value 0.019).

CONCLUSION

FVL mutation is more common in North Indians than previously believed and it predisposes the women to PE. MTHFR mutant allele is paradoxically protective. ACE polymorphism appears to predispose to severe PE but not nonsevere PE. No significant contribution of AGT polymorphism to PE is found.

The associations between maternal and fetal angiotensinogen M235T polymorphism and pregnancy-induced hypertension in Chinese women

This study was to investigate whether the maternal and fetal angiotensinogen (AGT) M235T polymorphism were associated with the risk of pregnancy-induced hypertension (PIH) in Chinese Han ethnic women. Using a case-control mother-baby dyads study, a total of 226 maternal/offspring pairs were recruited at Anyang Maternal and Child Health Hospital from January 2008 to December 2009. Genomic DNA was extracted from maternal venous and cord blood. We genotyped the AGT M235T polymorphism by using PCR-RFLP assay and examined the association with PIH using logistic regression analysis. In the current study, the maternal AGT M235T polymorphism showed no effect on the risk of PIH (P = .786) while the fetal AGT M235T polymorphism is significantly associated with PIH in Chinese Han ethnic women (P = .004). The fetus carrying TT genotype is a protective factor in developing PIH in the study population (OR = .28, 95% CI = .14-0.59).

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.

Impact of maternal angiotensinogen M235T polymorphism and angiotensin-converting enzyme insertion/deletion polymorphism on blood pressure, protein excretion and fetal outcome in pregnancy

OBJECTIVE

To test the hypothesis that genetically determined alterations of the renin-angiotensin system are associated with hypertensive disorders in pregnancy.

METHODS

A genetic association study was conducted at the obstetrics department of the Charité university hospital, Berlin, Germany. A total of 1068 Caucasian women were consecutively included after delivery and genotyped for the angiotensinogen M235T polymorphism and the angiotensin-converting enzyme (ACE) insertion/deletion polymorphism.

RESULTS

Women homozygous for the angiotensinogen T allele have significantly elevated mean systolic and diastolic blood pressures in the third trimester (118.4 +/- 1.1/71.5 +/- 0.7 versus 116.9 +/- 0.3/70.4 +/- 0.2 mmHg, n = 128 versus 940; P < 0.05). This finding is especially pronounced in the subgroup of primigravid women. The ACE polymorphism is not associated with blood pressure during pregnancy. None of the polymorphisms is associated with urinary protein excretion or oedema during pregnancy. Maternal polymorphisms do not influence fetal growth and birth weight. There is, however, an interesting trend towards an increased incidence of circulatory system malformations in newborns carrying alleles that are known to be associated with decreased intrinsic renin-angiotensin system activity.

CONCLUSION

We demonstrate for the first time in a large Caucasian population that a common maternal polymorphism of the angiotensinogen gene is related to a blood pressure increase during pregnancy. The angiotensinogen M235T polymorphism might contribute to the multifactorial pathogenesis of gestational hypertension and pre-eclampsia.

Angiotensin-converting enzyme I/D polymorphism and preeclampsia risk: evidence of small-study bias

BACKGROUND

Inappropriate activation of the renin-angiotensin system may play a part in the development of preeclampsia. An insertion/deletion polymorphism within the angiotensin-I converting enzyme gene (ACE-I/D) has shown to be reliably associated with differences in angiotensin-converting enzyme (ACE) activity. However, previous studies of the ACE-I/D variant and preeclampsia have been individually underpowered to detect plausible genotypic risks.

METHODS AND FINDINGS

A prospective case-control study was conducted in 1,711 unrelated young pregnant women (665 preeclamptic and 1,046 healthy pregnant controls) recruited from five Colombian cities. Maternal blood was obtained to genotype for the ACE-I/D polymorphism. Crude and adjusted odds ratio (OR) and 95% confidence interval (CI) using logistic regression models were obtained to evaluate the strength of the association between ACE-I/D variant and preeclampsia risk. A meta-analysis was then undertaken of all published studies to February 2006 evaluating the ACE-I/D variant in preeclampsia. An additive model (per-D-allele) revealed a null association between the ACE-I/D variant and preeclampsia risk (crude OR = 0.95 [95% CI, 0.81-1.10]) in the new case-control study. Similar results were obtained after adjusting for confounders (adjusted per-allele OR = 0.90 [95% CI, 0.77-1.06]) and using other genetic models of inheritance. A meta-analysis (2,596 cases and 3,828 controls from 22 studies) showed a per-allele OR of 1.26 (95% CI, 1.07-1.49). An analysis stratified by study size showed an attenuated OR toward the null as study size increased.

CONCLUSIONS

It is highly likely that the observed small nominal increase in risk of preeclampsia associated with the ACE D-allele is due to small-study bias, similar to that observed in cardiovascular disease. Reliable assessment of the origins of preeclampsia using a genetic approach may require the establishment of a collaborating consortium to generate a dataset of adequate size.

Genetic polymorphisms in vasoactive genes and preeclampsia: a meta-analysis

There are controversies in reports on the association of polymorphisms in endothelial nitric oxide synthase, angiotensinogen, angiotensin receptor type 1 and angiotensin-converting enzyme genes with an increased risk of developing preeclampsia. We performed a systematic search of published case-control studies through the PubMed database up to January 2006, and report the results of a meta-analysis of polymorphisms investigated in more than five studies: Glu298Asp in eNOS gene (9 analyses involving 1055 patients and 1788 controls), Met235Thr in AGT gene (13 analyses involving 1128 patients and 2278 controls), and intron 16 insertion-deletion polymorphism in ACE gene (10 analyses involving 1121 patients and 1361 controls). Statistically significant associations with preeclampsia were identified for the Met235Thr/AGT polymorphism: OR 1.65 (95% CI 1.19, 2.29) if the polymorphism is considered under the dominant genetic model, and OR 1.54 (95% CI 1.12, 2.11) under the recessive model. For insertion-deletion/ACE polymorphism, statistical significance was demonstrated when the polymorphism was considered under the recessive model: OR 1.51 (95% CI 1.17, 1.94). No single polymorphism was identified as having a major effect.