Genetic polymorphism of catechol-O-methyltransferase and cytochrome P450c17 in preeclampsia

Association of catechol-o-methyltransferase gene polymorphism with preeclampsia and biomarkers of oxidative stress: Study protocol for a prospective case-control study in Pakistan

BACKGROUND

Preeclampsia is one of the three leading causes of worldwide maternal mortality. Oxidative stress-mediated endothelial damage is expected to be an ultimate common mechanism in the pathophysiology of preeclampsia. The role of bioamines is also well-established in the induction of preeclampsia. This project is aimed to understand the factors which may affect the induction, progression, and aggravation of preeclampsia and oxidative stress during pregnancy. This study will explore the methylation pattern of the Catechol-O-methyltransferase gene to determine its role in the pathogenesis of preeclampsia, association of Val158Met polymorphism with a wide range of oxidative stress biomarkers, major antioxidants vitamins, and blood pressure regulating amines in preeclamptic Pakistani women.

METHODS AND ANALYSIS

In this prospective case-control study, 85 preeclamptic and 85 normotensive pregnant women will be recruited in their third trimesters. DNA will be extracted from peripheral blood and Val158Met polymorphism in the Catechol-O-methyltransferase gene will be examined on PCR amplified product digested with Hin1II (NlaIII) restriction enzyme, further validated by Sanger sequencing. Methylation-sensitive PCR will also be performed. Oxidative stress biomarkers, antioxidant vitamins, bioamines, and catechol-O-methyltransferase levels will be measured by ELISA. The data will be used to correlate maternal and fetal outcomes in both groups.

DISCUSSION

This study will help to identify and understand the multifactorial path and cause-effect relationship of gene polymorphism, oxidative stress biomarkers, major antioxidants vitamins, and blood pressure regulating amines in the pathogenesis and aggravation of preeclampsia in the Pakistani population. The outcome of this project will be particularly helpful in reducing the incidence of preeclampsia and further improving its management.

Catechol-O-methyltransferase and Pregnancy Outcome: an Appraisal in Rat

Catechol-O-methyltransferase (COMT) has been shown to be a key regulator of pregnancy outcomes in mouse, and its deficiency is causative in the development of a preeclampsia-like disease process. Preeclampsia is a human pregnancy disorder associated with failure of intrauterine trophoblast cell invasion and trophoblast-guided uterine spiral artery remodeling, which are not well-developed in mouse. The purpose of this study was to investigate COMT in rat, a species with deep intrauterine trophoblast invasion. To accomplish this task, we used clustered regularly interspaced short palindromic repeats/Cas9-mediated genome editing of the rat Comt gene. A Comt null rat model was established and its fertility characterized. Comt null male and female rats were viable and fertile. COMT deficiency did not significantly impact pregnancy outcomes, including litter size, placental and fetal weights, Mendelian and sex ratios, or pregnancy-dependent adaptations to hypoxia. Collectively, our findings indicate that pregnancy-associated phenotypic outcomes of COMT deficiency are not equivalent in mouse and rat. In rat, COMT is not required for a successful pregnancy outcome.

VAL158MET catechol O-methyltransferase polymorphism contributes to the development of preeclampsia

Objectives: Establishment of association between: (a) Val158Met COMT (G1947A) polymorphism and preeclampsia; (b) cytokines gene expression and COMT genotypes. Methods: 50 preeclampsia and 50 healthy pregnant women were enrolled. COMT genotyping was done by PCR/RFLP. TNF-α, IL-1β, and IL-6 mRNA levels were determined by Real-time PCR. Results: Variant (AA) homozygotes carried 3.7-fold increased preeclampsia odds, especially for severe (OR = 9.0, 95%CI (2.09-38.799)) and early forms (OR = 6.6, 95%CI (1.62-26.87)). AA homozygotes with PE had higher TNF-α levels compared to controls (P = 0.012). Conclusions: Val158Met COMT polymorphism increases preeclampsia risk. TNF-α expression and Val158Met COMT polymorphism have concomitant roles in PE pathogenesis.

Exploration of CYP21A2 and CYP17A1 polymorphisms and preeclampsia risk among Chinese Han population: a large-scale case-control study based on 5021 subjects

BACKGROUND

Several genome-wide association studies have identified single-nucleotide polymorphisms (SNPs), such as rs4409766, rs1004467, and rs3824755 in CYP17A1 and rs2021783 in CYP21A2, as new hypertension susceptibility genetic variants in the Chinese population. This study aimed to look into the relationship between preeclampsia (PE) and these SNPs in Chinese Han women.

METHODS

Overall, 5021 unrelated pregnant women were recruited, including 2002 patients with PE and 3019 normal healthy controls. The real-time PCR (TaqMan) method was applied to genotype these four polymorphisms.

RESULTS

A statistically obvious difference in the allelic frequencies was observed in CYP21A2 rs2021783 between cases and controls (χ2 = 7.201, Pc = 0.028 by allele), and the T allele was associated with the occurrence and development of PE (OR = 1.151, 95% CI 1.039-1.275). We also found a significant association between rs2021783 and the development of early-onset PE (Pc = 0.008 by genotype, Pc = 0.004 by allele). For rs1004467 and rs3824755, the distribution of allelic frequencies differed markedly between mild PE and control groups (χ2 = 6.843, Pc = 0.036; χ2 = 6.869, Pc = 0.036), and patients with the TT genotype of rs1004467 were less easy to develop mild PE than were those carrying the CT or CC genotype (χ2 = 7.002, Pc = 0.032, OR = 1.306, 95% CI 1.071-1.593). The GG genotype of rs3824755 appeared to a protective effect on the occurrence of mild PE (OR = 0.766, 95% CI 0.629-0.934).

CONCLUSIONS

CYP21A2 rs2021783 appears to be closely related to PE susceptibility, and CYP17A1 rs1004467 and rs3824755 seem to be closely associated with mild PE in Han women.

Catechol-O-methyltransferase Gene Polymorphism (Val158Met) and Development of Pre-eclampsia

OBJECTIVES

Catechol-O-methyltransferase (COMT) is a key enzyme in degradation pathways of estrogens and catecholamines. The present meta-analysis was done to elucidate the association of COMT Val158Met polymorphism with pre-eclampsia among pregnant women.

METHODS

A literature search was conducted in electronic databases including PubMed, Scopus, Elsevier, Springer and Google Scholar to find eligible studies. The pooled odds ratios (ORs) with 95% confidence intervals were calculated under dominant, recessive, co-dominant, and allelic models.

RESULTS

This meta-analysis included 6 eligible studies consisting 2596 cases and 4223 controls. The ORs for the COMT G472A polymorphism and pre-eclampsia were indicative of positive association under several genetic models. The results indicated that COMT Val158Met polymorphism was significantly associated with the increased risk of pre-eclampsia in recessive model (AA vs. AG + GG: OR = 1.522 [95% CI: 1.089-2.127]; p = 0.014), co-dominant model (AA vs. GG: OR = 1.605 [95% CI: 1.102-2.336]; p = 0.014), and allelic model (A vs. T: OR = 1.200 [95% CI: 1.021-1.402]; p = 0.021).

CONCLUSIONS

In summary, COMT Val158Met polymorphism is positively associated with the increased risk of pre-eclampsia among pregnant women, especially the homozygous carriers. It could be of value to investigate its association with pre-eclampsia in combination with additional risk factors. However, very large studies with different ethnic population are required to accurately demonstrate the role of this candidate gene in development of pre-eclampsia.

From Pregnancy to Preeclampsia: A Key Role for Estrogens

Preeclampsia (PE) results in placental dysfunction and is one of the primary causes of maternal and fetal mortality and morbidity. During pregnancy, estrogen is produced primarily in the placenta by conversion of androgen precursors originating from maternal and fetal adrenal glands. These processes lead to increased plasma estrogen concentrations compared with levels in nonpregnant women. Aberrant production of estrogens could play a key role in PE symptoms because they are exclusively produced by the placenta and they promote angiogenesis and vasodilation. Previous assessments of estrogen synthesis during PE yielded conflicting results, possibly because of the lack of specificity of the assays. However, with the introduction of reliable analytical protocols using liquid chromatography/mass spectrometry or gas chromatography/mass spectrometry, more recent studies suggest a marked decrease in estradiol levels in PE. The aim of this review is to summarize current knowledge of estrogen synthesis, regulation in the placenta, and biological effects during pregnancy and PE. Moreover, this review highlights the links among the occurrence of PE, estrogen biosynthesis, angiogenic factors, and cardiovascular risk factors. A close link between estrogen dysregulation and PE occurrence might validate estrogen levels as a biomarker but could also reveal a potential approach for prevention or cure of PE.

A Comparison of 2-Methoxyestradiol Value in Women with Severe Preeclampsia Versus Normotensive Pregnancy

INTRODUCTION

Preeclampsia is a pregnancy complication characterized by high blood pressure and proteinuria. Endothelial dysfunction is a major theory suggested as its aetiology. It is caused by anti-angiogenic condition characterized by low Vascular Endothelial Growth Factor (VEGF). An estradiol metabolite, called 2-Methoxy Estradiol (2-ME), is produced with the help of Catechol-O-Methyltransferase (COMT). This substance has an important role in VEGF expression. A 2-ME is suppressed in women with preeclampsia.

AIM

To compare 2-ME in women with severe preeclampsia and normotensive pregnancy.

MATERIALS AND METHODS

A total of 80 subjects qualified the inclusion and exclusion criteria, were divided into two groups (40 each): the severe preeclampsia and the normotensive pregnancy. Blood sample was collected and examined with the ELISA 2-ME kit (Cayman). The data were compared and calculated using Fisher-Exact test to examine 2-ME differences between the two groups.

RESULTS

Women age, parity, and gestational age showed a non significant difference between both groups. Nonetheless, the BMI before pregnancy and the history of preeclampsia in the past pregnancy showed significant differences. In this study, the 2-ME value was lower in the severe preeclampsia group compared to the normotensive.

CONCLUSION

This study concludes that 2-ME value in severe preeclampsia is lower than normotensive pregnancy. A lower 2-ME value may indicate COMT not producing enough 2-ME which in turn may cause the pre-eclampsia.

Evaluation of Glutathione Peroxidase 4 role in Preeclampsia

Preeclampsia (PE) is a pregnancy-specific syndrome that may be lifethreatening to pregnancies and fetus. Glutathione Peroxidase 4 (GPx4) is a powerful antioxidant enzyme that can provide protection from oxidative stress damage which plays a pivotal role in the pathology of PE. Therefore, this study aims to investigate the association between Gpx4 polymorphisms and the susceptibility to PE in Chinese Han women. TaqMan allelic discrimination real-time PCR was used to perform the genotyping of rs713041 and rs4807542 in 1008 PE patients and 1386 normotensive pregnancies. Obviously statistical difference of genotypic and allelic frequencies were found of rs713041 in GPx4 between PE patients and controls and the C allele has the higher risk for pathogenesis of PE (χ² = 12.292, P = 0.002 by genotype; χ² = 11.035, P = 0.001, OR = 1.216, 95% CI 1.084–1.365 by allele). Additionally, when subdividing these samples into CC + CT and TT groups, we found a significant difference between the two groups (χ² = 11.241, P = 0.001, OR = 1.417, 95% CI 1.155–1.738). Furthermore, the genotype of rs713041 was found to be associated with the mild, severe and early-onset PE. Our results suggest that rs713041 in GPx4 may play a key role in the pathogenesis of PE.

Protective Role of Maternal P.VAL158MET Catechol-O-Methyltransferase Polymorphism against Early-Onset Preeclampsia and its Complications

Background

Up until now there have been contradictory data about the association between p.Val158Met catechol-O-methyltransferase (COMT) polymorphism and risk of preeclampsia (PE). The goal of this study was to assess the potential correlation between p.Val158Met COMT polymorphism and risk of early-onset PE, risk of a severe form of early-onset PE, as well as risk of small-for-gestational-age (SGA) complicating PE.

Methods

The study included 47 early-onset PE patients and 47 control cases. Forty-seven early-onset PE patients were grouped by disease severity (33 patients with a severe form and 14 patients without severe features) and secondly by size for gestational age (12 patients with appropriate-for-gestational-age (AGA) and 35 patients with SGA size). p.Val158Met polymorphism was genotyped by PCR-RFLP analysis.

Results

Allele analysis showed significant difference in COMT allele distribution between early-onset PE and control group as well as early-onset PE SGA and controls (p=0.04057 and p=0.0411 respectively). A statistically significant distribution difference between the severe form and form without severe features of early-onset PE patients was not observed (p>0.05). The highest difference observed was in the allele recessive model where COMT MetMet genotype was associated with decreased risk of early-onset PE (OR=0.281; 95%CI = 0.092–0.7836) and PE complications including severe early-onset PE (OR= 0.304; 95%CI=0.086–0.944) and SGA early-onset PE (OR=0.284; 95%CI=0.081–0.874).

Conclusions

COMT may be used as a candidate gene for early-onset PE and its severe form and SGA complications.

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

OBJECTIVE

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

DESIGN

Prospective case-control study.

SETTING

University hospital.

PATIENT(S)

A total of 53 preeclamptic and 72 normal pregnant women.

INTERVENTION(S)

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

MAIN OUTCOME MEASURE(S)

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

RESULT(S)

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

CONCLUSION(S)

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

Maternal genotype and severe preeclampsia: a HuGE review

Severe preeclampsia is a common cause of maternal and perinatal morbidity worldwide. The disease clusters in families; however, individual genetic studies have produced inconsistent results. We conducted a review to examine relationships between maternal genotype and severe preeclampsia. We searched the MEDLINE and Embase databases for prospective and retrospective cohort and case-control studies reporting associations between genes and severe preeclampsia. Four reviewers independently undertook study selection, quality assessment, and data extraction. We performed random-effects meta-analyses by genotype and predefined functional gene group (thrombophilic, vasoactive, metabolic, immune, and cell signalling). Fifty-seven studies evaluated 50 genotypes in 5,049 cases and 16,989 controls. Meta-analysis showed a higher risk of severe preeclampsia with coagulation factor V gene (proaccelerin, labile factor) (F5) polymorphism rs6025 (odds ratio = 1.90, 95% confidence interval: 1.42, 2.54; 23 studies, I(2) = 29%), coagulation factor II (thrombin) gene (F2) mutation G20210A (rs1799963) (odds ratio = 2.01, 95% confidence interval: 1.14, 3.55, 9 studies, I(2) = 0%), leptin receptor gene (LEPR) polymorphism rs1137100 (odds ratio = 1.75, 95% confidence interval: 1.15, 2.65; 2 studies, I(2) = 0%), and the thrombophilic gene group (odds ratio = 1.87, 95% confidence interval: 1.43, 2.45, I(2) = 27%). There were no associations with other gene groups. There was moderate heterogeneity between studies and potential for bias from poor-quality genotyping and inconsistent definition of phenotype. Further studies with robust methods should investigate genetic factors that might potentially be used to stratify pregnancies according to risk of complications.

Catechol-O-methyltransferase Val158-Met polymorphism and a response of hyperactive-impulsive symptoms to methylphenidate: A replication study from South Korea

We investigated the association between the catechol-O-methyltransferase (COMT) Val(158)-Met (rs4680) genotype and both subjective and objective treatment responses to methylphenidate in Korean children with attention-deficit/hyperactivity disorder (ADHD). We enrolled 120 medication-naïve children with ADHD in an open-label, 8-week trial of methylphenidate. The participants were genotyped and evaluated using the Clinical Global Impression Scale and the ADHD Rating Scale-IV (ADHD-RS), and completed the Continuous Performance Test (CPT) before and after treatment. We found a significant association between the COMT Val/Val genotype and a good response, in terms of hyperactive-impulsive scores on the ADHD-RS (odds ratio (OR) = 2.61; p = 0.044) and response-time variability on the CPT (OR = 2.66; p = 0.028). The association of the COMT Val/Val genotype with a good response, in terms of response time variability, was significant in both the sub-sample of combined-type (OR = 3.45; p = 0.026) and sub-sample of inattentive-type (OR = 5.52; p = 0.029); but the association with a good response in terms of hyperactive-impulsive scores was not significant in sub-sample analyses. Although the reported nominally significant associations did not stay significant after correcting for multiple testing, our results support previous findings about the possible involvement of the COMT (Val(158)-Met) polymorphism in the treatment response to methylphenidate in children with ADHD.

2-methoxyestradiol plasma levels are associated with clinical severity indices and biomarkers of preeclampsia

We investigated whether clinical severity indices and biomarkers for preeclampsia (PE) are associated with low plasmatic 2-methoxyestradiol (2ME) in the third trimester of gestation. Blood was collected from 53 women with PE and 73 control pregnant women before parturition. The concentration of 2ME was significantly higher in controls than in patients with PE (2906.43 ± 200.69 pg/mL vs 1818.41 ± 189.25 pg/mL). The risk of PE decreased as 2ME levels increased. The 2ME values were negatively correlated with systolic peak arterial pressure and proteinuria in PE. Additionally, those women with PE with lower 2ME had a more serious clinical situation and needed a more aggressive therapy. Finally, 2ME levels (in patients with PE and total population) were significantly correlated with concentrations of soluble fms-like tyrosine kinase 1 and placental growth factor . Summarizing, patients with PE had lower 2ME levels that were correlated with different clinical indices and biomarkers of severity, indicating that 2ME could be taken into account for the clinical management of this syndrome.

Association of COMT G675A and MTHFR C677T polymorphisms with hypertensive disorders of pregnancy in Mexican mestizo population

OBJECTIVE

To investigate the relationship between COMT G675A and MTHFR C677T polymorphisms and hypertension disorders of pregnancy (HDP) in a Mexican mestizo population.

DESIGN AND METHODS

This case-control study involved 194 HDP and 194 normoevolutive pregnant women. The polymorphisms were genotyped by real time PCR.

RESULTS

Our results showed that the COMT AA genotype increases the risk to HDP (OR: 2.67; 95% CI 1.33-5.35), preeclampsia (OR: 2.69; 95% CI 1.00-7.22) and gestational hypertension (OR: 3.87; 95% CI 1.25-12.0). Furthermore, the double mutant genotype (COMTAA/MTHFRTT) potency the risk to HDP more than two times (OR: 5.21; 95% CI 1.12-24.3, p=0.019).

CONCLUSION

Our work provides evidence that COMT 675AA genotype is a risk factor for HDP and that this risk is increased by the presence of MTHFR 677TT genotype in a Mexican mestizo population.

Metabolic pathways involved in 2-methoxyestradiol synthesis and their role in preeclampsia

Preeclampsia (PE) remains a major cause of maternal/fetal morbidity-mortality worldwide. The first stage of PE is characterized by placental hypoxia due to a relative reduction in uteroplacental blood flow, resulting from restricted trophoblast invasion. However, hypoxia is also an essential element for the success of invasion. Under hypoxic conditions, 2-methoxyestradiol (2-ME) could induce the differentiation of cytotrophoblast cells into an invasive phenotype in culture. 2-Methoxyestradiol is generated by catechol-O-methyltransferase, an enzyme involved in the metabolic pathway of estrogens. During pregnancy, circulating 2-ME levels increase significantly when compared to the menstrual cycle. Interestingly, plasma levels of 2-ME are lower in women with PE than in controls, and these differences are apparent weeks or even months before the clinical manifestations of the disease. This article reviews the metabolic pathways involved in 2-ME synthesis and discusses the roles of these pathways in normal and abnormal pregnancies, with particular emphasis on PE.

2-methoxyoestradiol levels and placental catechol-O-methyltransferase expression in patients with late-onset preeclampsia

PURPOSE

Deficiencies in placental catechol-O-methyltransferase (COMT) and circulating 2-methoxyoestradiol (2-ME) have been shown to be related to early onset preeclampsia. The aim of this study was to investigate levels of 2-ME in the serum and urine of patients with late-onset preeclampsia and to compare those levels to those of normal pregnant women. In addition, we examined placental COMT expression in both groups.

METHODS

Fifteen patients with preeclampsia and 15 normal pregnant women were enrolled. 2-ME levels were evaluated by ELISA and placental COMT expression was examined by Western blot analysis.

RESULTS

2-ME levels in serum [median 181.1 pg/mL, interquartile range (IQR) 119.6-244.3 vs. 61.2 pg/mL, IQR 12.0-133.7, respectively, p = 0.004] and urine (median 143.3 pg/mL, IQR 35.0-328.2 vs. 0.5 pg/mL, IQR 0.4-4.6, respectively, p < 0.001) were significantly increased in patients with late-onset preeclampsia compared to those in normal pregnant women at term. There was no significant difference in placental COMT expression between the two groups.

CONCLUSION

Increased levels of 2-ME in patients with late-onset preeclampsia might be a product of a compensatory mechanism in patients with late-onset preeclampsia.

Molecular genetics of preeclampsia and HELLP syndrome - a review

Preeclampsia is characterised by new onset hypertension and proteinuria and is a major obstetrical problem for both mother and foetus. Haemolysis elevated liver enzymes and low platelets (HELLP) syndrome is an obstetrical emergency and most cases occur in the presence of preeclampsia. Preeclampsia and HELLP are complicated syndromes with a wide variety in severity of clinical symptoms and gestational age at onset. The pathophysiology depends not only on periconceptional conditions and the foetal and placental genotype, but also on the capability of the maternal system to deal with pregnancy. Genetically, preeclampsia is a complex disorder and despite numerous efforts no clear mode of inheritance has been established. A minor fraction of HELLP cases is caused by foetal homozygous LCHAD deficiency, but for most cases the genetic background has not been elucidated yet. At least 178 genes have been described in relation to preeclampsia or HELLP syndrome. Confined placental mosaicism (CPM) is documented to cause early onset preeclampsia in some cases; the overall contribution of CPM to the occurrence of preeclampsia has not been adequately investigated yet. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

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.

A low COMT activity haplotype is associated with recurrent preeclampsia in a Norwegian population cohort (HUNT2)

The etiology of preeclampsia is complex, with susceptibility being attributable to multiple environmental factors and a large genetic component. Although many candidate genes for preeclampsia have been suggested and studied, the specific causative genes still remain to be identified. Catechol-O-methyltransferase (COMT) is an enzyme involved in catecholamine and estrogen degradation and has recently been ascribed a role in development of preeclampsia. In the present study, we have examined the COMT gene by genotyping the functional Val108/158Met polymorphism (rs4680) and an additional single-nucleotide polymorphism, rs6269, predicting COMT activity haplotypes in a large Norwegian case/control cohort (n(cases)= 1135, n(controls)= 2262). A low COMT activity haplotype is associated with recurrent preeclampsia in our cohort. This may support the role of redox-regulated signaling and oxidative stress in preeclampsia pathogenesis as suggested by recent studies in a genetic mouse model. The COMT gene might be a genetic risk factor shared between preeclampsia and cardiovascular diseases.