Meta-analysis of the methylenetetrahydrofolate reductase C677T polymorphism and susceptibility to pre-eclampsia

Association between Vitamin D receptor (VDR) gene polymorphisms and hypertensive disorders of pregnancy: a systematic review and meta-analysis

Background

Hypertensive disorders of pregnancy (HDP) are currently one of the major causes of pregnancy-related maternal and fetal morbidity and mortality worldwide. Recent studies provide evidence that maternal Vitamin D receptor (VDR) gene polymorphisms probably play a key role by affecting the biological function of vitamin D in some adverse pregnancy outcomes, while the relationship between the VDR gene polymorphisms and the risk of HDP remains controversial in current studies. This systematic review and meta-analysis aimed to comprehensively evaluate the association of the VDR gene polymorphisms with HDP susceptibility.

Methods

This meta-analysis follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and a protocol has been registered in the PROSPERO (ID: CRD42022344383) before commencing this review. PubMed, Web of Science, Embase, and the Cochrane Library databases were searched until January 21, 2023. Case-control and cohort studies that reported the association of the VDR gene polymorphisms with HDP were included. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS) for non-randomized studies. The odds ratios (ORs) with corresponding 95% confidence intervals (CIs) of the five models (allele model, dominant model, recessive model, homozygous model, heterozygous model) were pooled respectively, and subgroup analysis was performed based on ethnicity.

Results

A total of ten studies were included. The VDR gene ApaI polymorphism was associated with HDP susceptibility in the dominant model (OR: 1.38; 95% CI [1.07-1.79]; P = 0.014) and the heterozygote model (OR: 1.48; 95% CI [1.12-1.95]; P = 0.006). In subgroup analysis, the heterozygote model (OR: 2.06; 95% CI [1.21-3.52]; P = 0.008) of the ApaI polymorphism was associated with HDP in Asians, but not in Caucasians.

Conclusion

The VDR gene ApaI polymorphism may be associated with HDP susceptibility. Insufficient evidence to support the existence of ethnic differences in this association.

Impact of the MTHFR C677T polymorphism on blood pressure and related central hemodynamic parameters in healthy adults

BACKGROUND

The C677T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) is associated with an increased risk of hypertension and cardiovascular disease. Riboflavin, the MTHFR cofactor, is an important modulator of blood pressure (BP) in adults homozygous for this polymorphism (TT genotype). The effect of this genetic variant on BP and related central hemodynamic parameters in healthy adults has not been previously investigated and was examined in this study.

METHODOLOGY

Brachial BP, central BP and pulse wave velocity (PWV; SphygmoCor® XCEL) were measured in adults 18-65 years pre-screened for MTHFR genotype. Riboflavin status was assessed using the erythrocyte glutathione reductase activation coefficient (EGRac) assay.

RESULTS

242 adults with the MTHFR 677TT genotype and age-matched non-TT (CC/CT) genotype controls were identified from a total cohort of 2,546 adults pre-screened for MTHFR genotype. The TT genotype was found to be an independent determinant of hypertension (P=0.010), along with low riboflavin status (P=0.002). Brachial systolic and diastolic BP were higher in TT v non-TT adults by 5.5±1.2 mmHg and 2.4±0.9 mmHg, respectively (both P<0.001). A stronger phenotype was observed in females, with an almost 10 mmHg difference in mean systolic BP in TT v non-TT genotype groups: 134.9 (95% CI 132.1-137.6) vs 125.2 (95% CI 122.3-128.0) mmHg; P<0.001. In addition, PWV was faster in women with the TT genotype (P=0.043).

CONCLUSION

This study provides the first evidence that brachial and central BP are significantly higher in adults with the variant MTHFR 677TT genotype, and that the BP phenotype is more pronounced in females. This article is protected by copyright. All rights reserved.

Validation and development of models using clinical, biochemical and ultrasound markers for predicting pre-eclampsia: an individual participant data meta-analysis

BACKGROUND

Pre-eclampsia is a leading cause of maternal and perinatal mortality and morbidity. Early identification of women at risk is needed to plan management.

OBJECTIVES

To assess the performance of existing pre-eclampsia prediction models and to develop and validate models for pre-eclampsia using individual participant data meta-analysis. We also estimated the prognostic value of individual markers.

DESIGN

This was an individual participant data meta-analysis of cohort studies.

SETTING

Source data from secondary and tertiary care.

PREDICTORS

We identified predictors from systematic reviews, and prioritised for importance in an international survey.

PRIMARY OUTCOMES

Early-onset (delivery at < 34 weeks' gestation), late-onset (delivery at ≥ 34 weeks' gestation) and any-onset pre-eclampsia.

ANALYSIS

We externally validated existing prediction models in UK cohorts and reported their performance in terms of discrimination and calibration. We developed and validated 12 new models based on clinical characteristics, clinical characteristics and biochemical markers, and clinical characteristics and ultrasound markers in the first and second trimesters. We summarised the data set-specific performance of each model using a random-effects meta-analysis. Discrimination was considered promising for C-statistics of ≥ 0.7, and calibration was considered good if the slope was near 1 and calibration-in-the-large was near 0. Heterogeneity was quantified using I ² and τ². A decision curve analysis was undertaken to determine the clinical utility (net benefit) of the models. We reported the unadjusted prognostic value of individual predictors for pre-eclampsia as odds ratios with 95% confidence and prediction intervals.

RESULTS

The International Prediction of Pregnancy Complications network comprised 78 studies (3,570,993 singleton pregnancies) identified from systematic reviews of tests to predict pre-eclampsia. Twenty-four of the 131 published prediction models could be validated in 11 UK cohorts. Summary C-statistics were between 0.6 and 0.7 for most models, and calibration was generally poor owing to large between-study heterogeneity, suggesting model overfitting. The clinical utility of the models varied between showing net harm to showing minimal or no net benefit. The average discrimination for IPPIC models ranged between 0.68 and 0.83. This was highest for the second-trimester clinical characteristics and biochemical markers model to predict early-onset pre-eclampsia, and lowest for the first-trimester clinical characteristics models to predict any pre-eclampsia. Calibration performance was heterogeneous across studies. Net benefit was observed for International Prediction of Pregnancy Complications first and second-trimester clinical characteristics and clinical characteristics and biochemical markers models predicting any pre-eclampsia, when validated in singleton nulliparous women managed in the UK NHS. History of hypertension, parity, smoking, mode of conception, placental growth factor and uterine artery pulsatility index had the strongest unadjusted associations with pre-eclampsia.

LIMITATIONS

Variations in study population characteristics, type of predictors reported, too few events in some validation cohorts and the type of measurements contributed to heterogeneity in performance of the International Prediction of Pregnancy Complications models. Some published models were not validated because model predictors were unavailable in the individual participant data.

CONCLUSION

For models that could be validated, predictive performance was generally poor across data sets. Although the International Prediction of Pregnancy Complications models show good predictive performance on average, and in the singleton nulliparous population, heterogeneity in calibration performance is likely across settings.

FUTURE WORK

Recalibration of model parameters within populations may improve calibration performance. Additional strong predictors need to be identified to improve model performance and consistency. Validation, including examination of calibration heterogeneity, is required for the models we could not validate.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42015029349.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 72. See the NIHR Journals Library website for further project information.

The association of MOV10 polymorphism and expression levels with preeclampsia in the Chinese Han population

BACKGROUND

To assess the relationship between MOV10 rs2932538 polymorphism and susceptibility to preeclampsia (PE) in the Chinese Han population and to investigate whether the placental expression of MOV10 have association with PE.

METHODS

We enrolled 1021 pregnant women with PE and 1594 normotensive pregnant women to analyze genotyping of MOV10 rs2932538. Clinical data and related test results of all subjects were collected and analyzed. For volunteers providing placentas, real-time PCR, Western blot, and immunohistochemistry were applied to assess the expression level of MOV10.

RESULTS

There was significant statistical difference between preeclamptic patients and healthy subjects in genotype distributions and alleles. The frequencies of genotypes TT+CT were significantly associated with the increased risk of preeclampsia. Besides, T alleles were found to be related to a higher risk of PE. Significant statistical difference was also observed on distributions of genotype in PE without/with severe features group compared or early onset/late onset versus controls. The placental expression of MOV10 was lower in preeclamptic women, however, no relationship was found between MOV10 expression level and MOV10 rs2932538 genotypes.

CONCLUSION

This study suggests that MOV10 rs2932538 polymorphism may be associated with PE susceptibility in the Chinese Han population. The placental expression of MOV10 decrease in PE but have no relationship with rs2932538 polymorphism.

Prediction of pre-eclampsia: review of reviews

OBJECTIVE

Primary studies and systematic reviews provide estimates of varying accuracy for different factors in the prediction of pre-eclampsia. The aim of this study was to review published systematic reviews to collate evidence on the ability of available tests to predict pre-eclampsia, to identify high-value avenues for future research and to minimize future research waste in this field.

METHODS

MEDLINE, EMBASE and The Cochrane Library including DARE (Database of Abstracts of Reviews of Effects) databases, from database inception to March 2017, and bibliographies of relevant articles were searched, without language restrictions, for systematic reviews and meta-analyses on the prediction of pre-eclampsia. The quality of the included reviews was assessed using the AMSTAR tool and a modified version of the QUIPS tool. We evaluated the comprehensiveness of search, sample size, tests and outcomes evaluated, data synthesis methods, predictive ability estimates, risk of bias related to the population studied, measurement of predictors and outcomes, study attrition and adjustment for confounding.

RESULTS

From 2444 citations identified, 126 reviews were included, reporting on over 90 predictors and 52 prediction models for pre-eclampsia. Around a third (n = 37 (29.4%)) of all reviews investigated solely biochemical markers for predicting pre-eclampsia, 31 (24.6%) investigated genetic associations with pre-eclampsia, 46 (36.5%) reported on clinical characteristics, four (3.2%) evaluated only ultrasound markers and six (4.8%) studied a combination of tests; two (1.6%) additional reviews evaluated primary studies investigating any screening test for pre-eclampsia. Reviews included between two and 265 primary studies, including up to 25 356 688 women in the largest review. Only approximately half (n = 67 (53.2%)) of the reviews assessed the quality of the included studies. There was a high risk of bias in many of the included reviews, particularly in relation to population representativeness and study attrition. Over 80% (n = 106 (84.1%)) summarized the findings using meta-analysis. Thirty-two (25.4%) studies lacked a formal statement on funding. The predictors with the best test performance were body mass index (BMI) > 35 kg/m² , with a specificity of 92% (95% CI, 89-95%) and a sensitivity of 21% (95% CI, 12-31%); BMI > 25 kg/m² , with a specificity of 73% (95% CI, 64-83%) and a sensitivity of 47% (95% CI, 33-61%); first-trimester uterine artery pulsatility index or resistance index > 90^th centile (specificity 93% (95% CI, 90-96%) and sensitivity 26% (95% CI, 23-31%)); placental growth factor (specificity 89% (95% CI, 89-89%) and sensitivity 65% (95% CI, 63-67%)); and placental protein 13 (specificity 88% (95% CI, 87-89%) and sensitivity 37% (95% CI, 33-41%)). No single marker had a test performance suitable for routine clinical use. Models combining markers showed promise, but none had undergone external validation.

CONCLUSIONS

This review of reviews calls into question the need for further aggregate meta-analysis in this area given the large number of published reviews subject to the common limitations of primary predictive studies. Prospective, well-designed studies of predictive markers, preferably randomized intervention studies, and combined through individual-patient data meta-analysis are needed to develop and validate new prediction models to facilitate the prediction of pre-eclampsia and minimize further research waste in this field. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Genetic variants in 3'-UTRs of MTHFR in the pregnancies complicated with preeclampsia and bioinformatics analysis

Preeclampsia (PE) as a pregnancy-specific disorder is the major cause of mortality and morbidity of mothers and fetuses. This study attempts to investigate the possible association between the 2572C>A (rs4846049) and 4869C>G (rs1537514) polymorphisms in the 3'- untranslated region of MTHFR gene and the risk of PE. A total of 198 patients diagnosed with PE and 171 unrelated, age matched healthy pregnant women, were recruited for this case-control study. The MTHFR 2572C>A and 4869C>G genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The CG genotype of MTHFR 4869C>G was associated with decreased risk of PE, and this genotype was found to be a protective factor for PE susceptibility. There was no significant difference in the genotypes of MTHFR 2572C>A polymorphism between PE patients and control group. The frequency of combined AC/CG genotypes of MTHFR 2572C>A and 4869C>G polymorphisms were less frequent in PE patients and were associated with a lower risk of PE. The C-G and A-G haplotypes of MTHFR 2572C>A and 4869C>G polymorphisms were significantly lower in PE patients. In conclusion, the CG genotype of MTHFR 4869C>G polymorphism was associated with a lower risk of PE. No association was found between MTHFR 2572C>A polymorphism and PE.

Association Between Gene Polymorphisms on Chromosome 1 and Susceptibility to Pre-Eclampsia: An Updated Meta-Analysis

Background

This meta-analysis enabled us to obtain a precise estimation of the association between gene polymorphisms on chromosome 1 (MTHFR, AGT, F5, IL-10, LEPR) and the susceptibility to pre-eclampsia (PE) in order to reach a uniform conclusion.

Material/Methods

Web of Science, PubMed, EMBASE, Cochran Library (CENTRAL), and Chinese databases (Chinese National Knowledge Infrastructure-CNKI and Wan Fang) were electronically searched to select relevant studies for this meta-analysis. We selected 95 case-control studies investigating 5 genes (MTHFR, AGT, F5, IL-10, and LEPR) with 8 SNPs. Odds ratios (OR) with their 95% confidence intervals (CI) were used for estimating the association.

Results

A total of 16 646 PE patients and 28 901 normal-pregnancy patients were included in this meta-analysis. The overall results suggested that rs1801133 of MTHFR (OR=1.17, 95% CI: 1.05–1.13) and rs6025 of F5 (OR=1.53, 95%CI: 1.07–2.20) are significantly associated with PE, whereas rs1801131 of MTHFR, rs699 and rs4762 of AGT, rs1800896 and rs1800871 of IL-10, and rs1137101 of LEPR have no significant association with PE. Subgroup analysis by ethnicity revealed that, except for MTHFR rs1801133 and F5 rs6025 in Caucasians, which were significantly associated with an increased risk of PE, none of these SNPs were significantly associated with PE. As suggested by a symmetric funnel plot in conjunction with the Egger’s test, there was no significant publication bias in MTHFR rs1801133 (P=0.318) and rs1801131 (P=0.204), F5 rs6025 (P=0.511), LEPR rs1137101 (P=0.511), AGT rs4762 (P=0.215) and rs699 (P=0.482), IL-10 rs1800871 (P=0.955), and rs1800896 (P=0.144).

Conclusions

This meta-analysis provides evidence that MTHFR rs1801133 and F5 rs6025 are associated with an increased risk of PE, especially in Caucasians. However, we do not have sufficient evidence to conclude there is a significant association between other gene polymorphisms and PE.

Potential role of folate in pre-eclampsia

Dietary deficiencies of folate and other B vitamin cofactors involved in one-carbon metabolism, together with genetic polymorphisms in key folate-methionine metabolic pathway enzymes, are associated with increases in circulating plasma homocysteine, reduction in DNA methylation patterns, and genome instability events. All of these biomarkers have also been associated with pre-eclampsia. The aim of this review was to explore the literature and identify potential knowledge gaps in relation to the role of folate at the genomic level in either the etiology or the prevention of pre-eclampsia. A systematic search strategy was designed to identify citations in electronic databases for the following terms: folic acid supplementation AND pre-eclampsia, folic acid supplementation AND genome stability, folate AND genome stability AND pre-eclampsia, folic acid supplementation AND DNA methylation, and folate AND DNA methylation AND pre-eclampsia. Forty-three articles were selected according to predefined selection criteria. The studies included in the present review were not homogeneous, which made pooled analysis of the data very difficult. The present review highlights associations between folate deficiency and certain biomarkers observed in various tissues of women at risk of pre-eclampsia. Further investigation is required to understand the role of folate in either the etiology or the prevention of pre-eclampsia.

Folate metabolism gene polymorphisms MTHFR C677T and A1298C and risk for preeclampsia: a meta-analysis

OBJECTIVES

MTHFR C677T and A1298C have been associated with the risk of preeclampsia (PE), but with conflicting results. We performed this meta-analysis to derive a more precise estimation of the association between MTHFR polymorphisms and PE.

STUDY DESIGN

An electronic search of PubMed and Chinese Biomedicine database was conducted to select studies for meta-analysis. 54 case controlled studies containing MTHFR C677T and A1298C gene polymorphisms were chosen, and odds ratio (OR) with confidence interval (CI) was used to assess the strength of this association.

RESULT

These studies evaluated 7398 cases and 11230 controls for MTHFR C677T. The overall results suggested that MTHFR C677T was associated with the risk of PE. (T vs. C: OR = 1.157, 95% CI: 1.057-1.266, p = 0.002; TT + CT vs. CC: OR = 1.165, 95% CI : 1.049-1.293, P = 0.004; TT vs. CT + CC: OR = 1.371, 95% CI: 1.153-1.63, p < 0.001). We also evaluated 1103 cases and 988 controls for MTHFR A1298C but could not demonstrate an increased risk of PE for this polymorphism (p = 0.667). A symmetric funnel plot, the Egger's test (p = 0.819) suggested a lack of publication bias.

CONCLUSION

This meta-analysis supports the idea that MTHFR C677T genotype is associated with increased risk for PE, especially in the case of Asians and Caucasians.

Associations of MTHFR gene polymorphisms with hypertension and hypertension in pregnancy: a meta-analysis from 114 studies with 15411 cases and 21970 controls

BACKGROUND

Several epidemiological studies have investigated the associations of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms with hypertension (H) or hypertension in pregnancy (HIP). However, the results were controversial. We therefore performed a comprehensive meta-analysis to provide empirical evidences on the associations.

METHODOLOGIES

The English and Chinese databases were systematically searched to identify relevant studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the associations. Meta-regression, subgroup analysis, sensitivity analysis, cumulative meta-analysis and assessment of publication bias were performed in our study.

PRINCIPAL FINDINGS

A total of 114 studies with 15411 cases and 21970 controls were included, 111 studies with 15094 cases and 21633 controls for the C677T polymorphism and 21 with 2533 cases and 2976 controls for the A1298C polymorphism. Overall, the C677T polymorphism was significantly associated with H and HIP (H & HIP: OR = 1.26, 95% CI = 1.17-1.34; H: OR = 1.36, 95% CI = 1.20-1.53; HIP: OR = 1.21, 95% CI = 1.08-1.32). Stratified analysis by ethnicity revealed a significant association among East Asians and Caucasians, but not among Latinos, Black Africans, and Indians and Sri Lankans. In the stratified analyses according to source of controls, genotyping method, sample size and study quality, significant associations were observed in all the subgroups, with the exception of population based subgroup in H studies and large sample size and "others" genotyping method subgroups in HIP studies. For the A1298C polymorphism, no significant association was observed either in overall or subgroup analysis under all genetic models.

CONCLUSIONS

This meta-analysis suggests that the MTHFR C677T rather than A1298C polymorphism may be associated with H & HIP, especially among East Asians and Caucasians.

MTHFR 677TT genotype and disease risk: is there a modulating role for B-vitamins?

Methylenetetrahydrofolate reductase (MTHFR) is a critical folate-metabolising enzyme which requires riboflavin as its co-factor. A common polymorphism (677C→T) in the MTHFR gene results in reduced MTHFR activity in vivo which in turn leads to impaired folate metabolism and elevated homocysteine concentrations. Homozygosity for this polymorphism (TT genotype) is associated with an increased risk of a number of conditions including heart disease and stroke, but there is considerable variability in the extent of excess risk in various reports. The present review will explore the evidence which supports a role for this polymorphism as a risk factor for a number of adverse health outcomes, and the potential modulating roles for B-vitamins in alleviating disease risk. The evidence is convincing in the case which links this polymorphism with hypertension and hypertensive disorders of pregnancy, particularly preeclampsia. Furthermore, elevated blood pressure was found to be highly responsive to riboflavin intervention specifically in individuals with the MTHFR 677TT genotype. Future intervention studies targeted at these genetically predisposed individuals are required to further investigate this novel gene-nutrient interaction. This polymorphism has also been associated with an increased risk of neural tube defects (NTD) and other adverse pregnancy outcomes; however, the evidence in this area has been inconsistent. Preliminary evidence has suggested that there may be a much greater need for women with the MTHFR 677TT genotype to adhere to the specific recommendation of commencing folic acid prior to conception for the prevention of NTD, but this requires further investigation.

[Hereditary thrombophilias and placental-mediated pregnancy complications in the II./III. trimester]

Placental-mediated pregnancy complications (PmC) like preeclampsia, intrauterine growth restriction and placental abruption are common causes of fetal and maternal morbidity and mortality. The high prevalence of hereditary thrombophilias in case-control studies associated with pathological morphological findings of the placenta in these cases gave evidence for the association between hereditary thrombophilias and PmC. However, data from the literature are inconsistent, since subsequent prospective cohort studies could not demonstrate significant associations between inherited thrombophilia and PmC. Because of the multifactorial aetiology of PmC it may be difficult to prove, that hereditary thrombophilias are independent risk factors for PmC. Current guidelines do not recommend screening for inherited thrombophilias in patients with previous PmC. Evidence from current in vitro studies have shown, that heparin has beneficial non-anticoagulatory effects on trophoblast invasion. Retrospective case-control studies and recently published randomised controlled cohort studies have shown, that prophylactic administration of low-molecular-weight heparin (LWH), started in early pregnancy, may lead to a significant reduction in the incidence of PmC in subsequent pregnancies in patients with and without hereditary thrombophilias and previous PmC.

CONCLUSION

Large, well-designed multicenter studies are needed to elucidate the role of hereditary thrombophilias in cases of PmC and to confirm the benefit of LWH for subsequent pregnancy outcomes.

Methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism and risk of preeclampsia: an updated meta-analysis based on 51 studies

BACKGROUND AND AIMS

The methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism has been considered to be associated with preeclampsia (PE), but the results from previous studies were conflicting. The present study aimed at investigating the frequency of preeclampsia according to the distribution polymorphism using a meta-analysis on the published studies.

METHODS

The English and Chinese databases were searched to identify eligible studies published in English before August 2012. Data were extracted using standardized methods. The association was assessed by odds ratio (OR) with 95% confidence intervals (CI). Begg's test was used to measure publication bias.

RESULTS

A total of 51 case-control studies containing 6,403 patients and 11,346 controls were involved in this meta-analysis. Significant associations were detected between MTHFR C677T polymorphism and risk of PE in the overall population for TT vs. CC (OR = 1.280, 95% CI: 1.074-1.525), recessive model (OR = 1.264, 95% CI: 1.067-1.303), and dominant genetic model (OR = 1.174, 95% CI: 1.057-1.303); in Caucasian population for dominant model (OR = 1.136, 95% CI: 1.022-1.263), and in East Asia population for TT vs. CC (OR = 2.199, 95% CI: 1.366-3.924) CT vs. CC (OR = 1.453, 95% CI: 1.001-2.109), recessive model (OR = 1.742, 95% CI: 1.202-2.525), and dominant model (OR = 1.783, 95% CI: 1.271-2.501). Conversely, no associations were detected in Latin America, South Asia, and Africa populations.

CONCLUSIONS

Results of the meta-analysis suggest that the MTHFR C677T polymorphism was associated with risk of PE in overall, Caucasian, and East Asia populations. Nevertheless, the results for Latino, East Asians, South Asians and Africans should be interpreted with caution due to the small sample size.