No Association of C677T Methylenetetrahydrofolate Reductase and an Endothelial Nitric Oxide Synthase Polymorphism with Recurrent Pregnancy Loss

Investigating the Association of MTHFR C677T Gene Polymorphism with Recurrent Spontaneous Abortion Among Azerbaijani Women from Northwest Iran

Background: Recurrent spontaneous abortion (RSA), defined as two or more succeeding abortions during 20 weeks of gestation, affects 3-5% of pregnancies. Several studies have found that most women with RSA had at least one (and sometimes two copies) of the methylenetetrahydrofolate reductase (MTHFR) C677T variant. Materials and Methods: The study involved 118 women who had two or more spontaneous abortions (SAs) as the case group and 118 women who had at least one live birth but no SA as the control group. Clinical features such as age, body mass index (BMI), medication received, family history of abortion, and thrombophilia were investigated. Real-time PCR was used for genotyping subjects for MTHFR C677T gene polymorphism. Results: Significant differences in age, BMI, and medication received characters have been shown between those in the patients' group. For the MTHFR C677T gene, the genotypes for the patients' group were 36%, 60%, and 4%, whereas the genotypes for the control group were 30%, 58%, and 12%. In addition, the C and T allelic frequencies were 59% and 41% in the healthy control group and 67% and 33% in the patients' group, respectively. A significant association was found between the TT genotype and RSA. A 3.84-fold increased risk of RSA was associated with the TT genotype (odds ratio = 3.84, confidence interval: 1.28-10.93, p-value = 0.02). Conclusions: In this study, homozygosity for the T allele was significantly lower in the RSA-affected than in healthy women, whereas heterozygosity did not vary substantially between the two groups, which was in line with other studies.

Maternal candidate gene variants, epigenetic factors, and susceptibility to idiopathic recurrent pregnancy loss: A systematic review

BACKGROUND

Recurrent pregnancy loss is defined as the loss of two or more pregnancies and is a distressing condition for couples.

OBJECTIVE

To investigate the relationship between variants in the candidate susceptibility genes and epigenetic factors to identify risk factors for idiopathic recurrent pregnancy loss (iRPL).

SEARCH STRATEGY

A systematic literature search was performed using PubMed, Google Scholar, ScienceDirect, and Scopus databases. Insilico analysis was carried out using ShinyGO and STRING software.

SELECTION CRITERIA

Research papers examining the association between variations in genetic and epigenetic factors and iRPL.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by two authors.

MAIN RESULTS

In total, 83 research papers were finally selected for the present study. Among all the genes involved in the pathogenesis of recurrent pregnancy loss, polymorphisms in IL superfamily genes, VEGF, ESR, and MTHFR were the most investigated.

CONCLUSION

Polymorphisms in angiogenesis, immune tolerance, and thrombophilia pathway genes, which occur independently or synergistically, may lead to various complications during fetal development. Identification of multi-allele risk variants and epigenetic factors in women will be helpful in the identification of high-risk pregnancies.

PROSPERO REGISTRATION NUMBER

Prospero CRD42021287315.

Thrombophilic gene polymorphisms and recurrent pregnancy loss: a systematic review and meta-analysis

PURPOSE

Recurrent pregnancy loss (RPL) is affecting 1-4% of women who conceive approximately, and no cause could be found in more than 50% of women suffering from RPL. Inherited thrombophilias have got increasing attention in women with unexplained RPL, so we aim to explore the relationship among these most common thrombophilic polymorphisms and RPL through a literature review and meta-analysis.

METHODS

Observational studies from PubMed, Embase, Cochrane, and Web of Science from 1997 to 7 April 2022 were searched. For each genetic variant, a fixed or random-effect model was used according to the heterogeneity test to calculate pooled ORs and 95% CIs for both dominant and recessive genetic models. Egger's line regression test was used to assess publication bias. The quality of the included articles was assessed by the Newcastle Ottawa scale.

RESULTS

A total of 124 articles comprising 17,278 RPL patients and 16,021 controls were included. Results showed that hyperhomocysteinemia (MTHFR) C677T (dominant model: OR, 1.43; 95% CI, 1.25-1.64; recessive model: OR, 1.60; 95% CI, 1.36-1.87), MTHFR A1298C (dominant model: OR, 1.66; 95% CI, 1.26-2.18; recessive model: OR, 1.79; 95% CI, 1.42-2.26), PAI-1 4G/5G (dominant model: OR, 1.67; 95% CI, 1.36-2.06; recessive model: OR, 1.80; 95% CI, 1.39-2.32), angiotensin-converting enzyme I/D (OR, 1.23; 95% CI, 1.00-1.53), Factor XIII V34L (OR, 1.38; 95% CI, 1.02-1.87), and β-fibrinogen-455G/A (OR, 1.60; 95% CI, 1.02-2.51) were significantly associated with RPL.

CONCLUSION

This study provides potentially useful clinical markers to evaluate the risk of RPL or to help unexplained RPL patients identify possible causes, which may allow for targeted treatment.

A meta-analysis for association of eNOS VNTR 4b/a, - 786 T > C and + 894G > T polymorphisms with risk of recurrent pregnancy loss

BACKGROUND

The association of polymorphisms at nitric oxide synthases (eNOS) gene with recurrent pregnancy loss (RPL) susceptibility has been the focus of attention in several studies. However, the conclusions have been divergent and controversial. Therefore, we performed this study to precisely evaluate the association of eNOS polymorphisms with the risk of RPL.

METHODS

A universal search in PubMed, Web of Knowledge, SciELO, MedRxiv, Scopus and web of Science was performed to identify relevant studies up to January 25, 2020.

RESULTS

A total of 39 eligible studies including 15 studies with 2274 cases and 1933 controls on VNTR 4b/a, nine studies with 1640 cases and 1268 controls on -786C > T, and 15 studies with 2660 cases and 2557 controls on + 894G > T polymorphism were selected. Pooled data revealed that eNOS VNTR 4b/a (dominant model: OR = 1.174, 95% CI 1.021-1.350, p = 0.025) and + 894G > T (allele model: OR = 1.278, 95% CI 1.024-1.595, p = 0.030; homozygote model: OR = 1.442, 95% CI 1.084-1.917, p = 0.012; dominant model: OR = 1.305, 95% CI 1.006-1.693, p = 0.045; and recessive model: OR = 1.378, 95% CI 1.045-1.817, p = 0.023) polymorphisms were significantly associated with an increased risk of RPL, but not  - 786 T > C. Stratified analysis by ethnicity revealed that the eNOS + 894G > T was associated with RPL risk in Asians.

CONCLUSIONS

To sum up, our results indicated that the eNOS VNTR 4b/a and + 894G > T polymorphisms might be contributing to RPL development, but not the  - 786C > T polymorphism.

Meta-analysis: association of homocysteine with recurrent spontaneous abortion

We analyzed the differences in serum homocysteine levels between patients with a history of recurrent spontaneous abortion (RSA) and those who had not experienced pregnancy-related complications. To this end, we retrieved literature and data on the association of RSA and serum homocysteine levels published before September 1st 2019 from the PubMed, EMBASE, China National Knowledge Infrastructure, and Wanfang databases. We further narrowed our literature review by focusing on peer-reviewed and full-text literature reporting on studies that used similar research methods and provided raw data or means and standard deviations while reporting results. Utilizing Stata 12.0 for a combined statistical analysis of the data, we assessed the quality of the included literature using the Newcastle Ottawa Scale. Patients who experienced RSA had higher serum homocysteine levels than the controls, with the difference being statistically significant (p < .05). High serum homocysteine levels may be an important risk factor for RSA, indicating that homocysteine may be useful as a noninvasive marker for the diagnosis of recurrent abortions.

Variants c.677 C>T, c.1298 A>C in MTHFR, and c.66 A>G in MTRR Affect the Occurrence of Recurrent Pregnancy Loss in Chinese Women

Objective: Although genetic variants of key enzymes in the folic acid-methionine metabolic circulation, including methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) were thought to be related to the risk of recurrent pregnancy loss (RPL), the results of recent studies have been inconsistent. Therefore, the present retrospective case-control study was designed to explore whether the variants c.66A>G in MTRR and c.677C>T and c.1298A>C in MTHFR are associated with the susceptibility of RPL in Southeast Chinese women. Materials and Methods: In total, samples from 237 RPL patients and 618 healthy controls were collected and genotyped by fluorescent quantitative polymerase chain reaction. The frequencies of the variants were calculated and compared between the two groups. The relative risk of the various genotypes was further determined by calculating the odds ratio (OR) at a 95% confidence interval (CI). Results: A significant positive correlation was observed between the variants MTHFR c.677C>T, MTHFR c.1298A>C, MTRR c.66A>G, and RPL susceptibility (MTHFR c.677C>T, OR = 0.74, 95% CI = 0.58-0.95, p = 0.02; MTHFR c.1298A>C, OR = 1.39, 95% CI = 1.09-1.77, p = 0.008; MTRR c.66A>G, OR = 1.38, 95% CI = 1.10-1.73, p = 0.006). Further analysis of the genotypic distributions of the three variants between the two groups showed that the MTHFR c.677C>T heterozygote was associated with lower RPL risk, while the MTHFR c.1298A>C variant and MTRR c.66A>G heterozygote were correlated with higher RPL risk (dominant model, MTHFR c.677C>T, OR = 0.70, 95% CI = 0.52-0.95, p = 0.02; MTHFR c.1298A>C, OR = 1.39, 95% CI = 1.03-1.88, p = 0.032; MTRR c.66A>G, OR = 1.62, 95% CI = 1.20-2.19, p = 0.002). Conclusion: MTHFR c.677C>T and c.1298A>C and MTRR c.66A>G were associated with RPL in Southeast Chinese women.

Perinatal complications related to inherited thrombophilia: review of evidence in different regions of the world

The term thrombophilia describes disorders associated with an increased predisposition of developing venous thromboembolism (VTE). It may be acquired, like in those with antiphospholipid syndrome or inherited. The aim of this review was to compare the complications and outcomes of pregnancies in women with inherited thrombophilia between different populations, including the population of our country where the results of the research are scarce. The review of literature included all papers indexed on PubMed and Medline in the last 20 years, with different study design, including other reviews of literature, systematic reviews with meta-analysis and several case-control studies and population-based cohort studies. We aimed to cover as many geographic regions as possible with the aim to show the differences in the different parts of the world and including our country. Our analysis showed that types of thrombophilia differ in different geographic regions. Also, the differences exist between one particular type of thrombophilia in different regions. Nevertheless, no matter what the differences are between prevalence, all authors investigated the association between inherited thrombophilia and poor pregnancy outcome and managed to find some kind of association. The case with our own country is similar. Although we lack in studies with this issue and the design of published studies is not powerful enough, we may conclude that in our samples, women with thrombophilia are in potential risk of several poor pregnancy outcomes. Further and better analyses are necessary to prove this hypothesis not only on the level of study sample but also on general population. Given the fact that thrombophilia certainly affects the pregnancy and its outcome, the urge to perform screening tests in every woman suspected to have this kind of disorder and with respect to differences that exist in different world regions is inevitable.

Gene polymorphism associated with endothelial nitric oxide synthase (4VNTR, G894T, C786T) and unexplained recurrent spontaneous abortion risk: A meta-analysis

To evaluate the association between endothelial nitric oxide synthase gene polymorphisms (4VNTR A/B, G894T, C786T) and risk of URSA.Related case-control studies were collected by computers. A meta-analysis was conducted using Stata 12.0 software to assess the strength of association.Altogether 37 articles were examining the relationship between endothelial nitric oxide synthase gene polymorphisms and URSA, among which sixteen (16) studies were related to 4VNTR, twelve (12) to G894T, and nine (9) to C786T, the study suggested that 4VNTR A/B polymorphism was closely connected with URSA risk under all gene models except for recessive model (AA vs. BB + AB). The integrated result which indicated the association between G894T gene mutation and URSA risk had been shown under homozygote (TT vs. GG; OR 1.585, 95%CI 1.175-2.138) and recessive models (TT vs. TG + GG; OR 1.530, 95%CI 1.142-2.052). Considering heterogeneity in the remaining gene models, subgroup analysis was performed on ethnicity, and the results showed that it was the dominant (TT + TG vs. GG; OR 1.585, 95%CI 1.175-2.138) and additive models (T vs. G; OR 1.727, 95%CI 1.372-2.175) of G894T in Asians and the heterozygote model (TG vs. GG; OR 1.015, 95%CI 0.846-1.217) in Caucasians that were associated with URSA (P < .05). Besides C786T gene was significantly connected with URSA under all models except for additive model (T vs. C).It is of great guiding significance for screening out and preventing URSA among high-risk women via testing on 4VNTR A/B, G894T, C786T eNOS under gene models mentioned above which are closely associated with URSA.

Association of parental methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism in couples with unexplained recurrent pregnancy loss

Objective

The aim of this study was to identify the association of parental MTHFR C677T gene polymorphism in couples with and without RPL history.

Results

During the study, 21.4% (15/70) of Ala222Val polymorphism was observed among RPL couples while no polymorphism was seen among normal, healthy couples. Our study did not find any association between MTHFR C677T polymorphism and gender (p > 0.05), gestational period (p > 0.05), geographical region (p > 0.05) and menstrual history (p > 0.05). However, significant association was seen between MTHFR C677T polymorphism and number of losses (p < 0.05), concluding that the risk of the polymorphism increased with the increase in number of losses. Significant variation in the MTHFR C677T genotype with number of losses among RPL couples were seen but not with other study variables.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3321-x) contains supplementary material, which is available to authorized users.

Association of endothelial nitric oxide synthase gene variants (-786 T>C, intron 4 b/a VNTR and 894 G>T) with idiopathic recurrent pregnancy loss: A case-control study with haplotype and in silico analysis

OBJECTIVE(S)

Many lines of evidence suggest that reduced production of nitric oxide (NO) due to single nucleotide polymorphisms in endothelial nitric oxide synthase (eNOS) gene may affect the implantation and maintenance of pregnancy. Accordingly, our objective was to investigate whether the eNOS polymorphisms (-786 T>C, intron 4 b/a VNTR and 894 G>T) and haplotypes may be associated with increased susceptibility to recurrent pregnancy loss (RPL).

STUDY DESIGN

A total of 130 women with a history of two or more unexplained consecutive first trimester miscarriages and 110 ethnically matched women with at least two normal pregnancies and no history of pregnancy loss were included in the study as cases and controls, respectively. To identify the genotypes, we used polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (PCR-RFLP) methods In addition, an in silico analysis was conducted to predict the possible effects of the eNOS 894 G>T polymorphism on the structure and function of eNOS mRNA and protein using prediction servers.

RESULTS

Our findings revealed that the prevalence of eNOS -786 T>C polymorphism, eNOS -786C allele and TC+CC genotype in cases were significantly higher than those in healthy controls (p<0.05). Also, the combination genotypes -786TT/4b4a and -786TT/894GG were significantly associated with reduced risk of RPL. We also found that the C-4a-G haplotype of the eNOS gene studied polymorphisms was significantly associated with a predisposition to RPL (odds ratio, 3.219; 95% confidence interval, 1.649-6.282; p=0.0003). The in silico analysis showed that the eNOS 894 G>T polymorphism couldn't affects eNOS mRNA and protein significantly.

CONCLUSION

Our findings provide evidence to support the hypothesis that eNOS -786 T>C polymorphism and the -786C-4a-894G haplotype are associated with the high risk of RPL.

Methylenetetrahydrofolate Reductase C677T Polymorphism and Recurrent Pregnancy Loss Risk in Asian Population: A Meta-analysis

The C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene was implicated to be associated with thrombophilia due to its role in catalyzing the formation of 5-methylenetetrahydrofolate, a co-substrate for the conversion of homocysteine to methionine. Several case-control studies were investigated MTHFR C677T polymorphism as risk for recurrent pregnancy loss (RPL). These studies rendered contradictory results, some indicating that the polymorphism is associated with the risk of RPL whereas others concluded there is no association. To shed light on these inconclusive findings, a meta-analysis of all available studies published from Asian population relating the C677T polymorphism to the risk of RPL was conducted. The following electronic databases were searched without language restrictions: PubMed, Google Scholars, Elsevier and Springer Link up to December, 2015. Meta-analysis was performed using MetaAnalyst and Mix version 1.7. Meta-analysis results suggested that MTHFR C677T polymorphism contributed to the increased RPL risk in Asian population using all five genetic models (for T vs. C: OR 1.35, 95 % CI 1.09-1.68, p = 0.009; for TT + CT vs. CC: OR 1.44, 95 % CI 1.14-1.82, p = 0.006; for CT vs. CC: OR 1.39, 95 % CI 1.07-1.8, p = 0.01; for TT vs. CC: OR 1.79, 95 % CI 1.23.2.6, p = 0.007; for TT vs. CT + CC: OR 1.61, 95 % CI 1.02-2.56, p = 0.04). In conclusion, this meta-analysis demonstrates a strong association between the MTHFR C677T variant and RPL in Asian population and raising the importance of the use of folate in its treatment and prevention.

A critical update on endothelial nitric oxide synthase gene variations in women with idiopathic recurrent spontaneous abortion: genetic association study, systematic review and meta-analyses

A number of case-control studies investigated the association between idiopathic recurrent spontaneous abortion (IRSA) and variations in the gene encoding endothelial nitric oxide synthase (NOS3), but yielded contradictory results. Our aim was to test the association of the NOS3 variable number of tandem repeats (VNTR) in intron 4 and +894 G/T single-nucleotide polymorphism (SNP) with IRSA in Slovenian women (148 IRSA and 149 control women), conduct a systematic review of literature on the association between NOS3 gene variations and IRSA, and perform meta-analyses of studies that met the inclusion criteria, defined by virtue of the European Society for Human Reproduction and Embryology evidence-based guidelines for recurrent spontaneous abortion. Genotyping was performed using PCR and restriction fragment length polymorphism methods. The systematic review of literature (English language) was conducted using PubMed and Scopus databases, to 1 November 2014. We determined no association of IRSA with the VNTR in intron 4 and +894 G/T SNP in Slovenian women. Furthermore, 16 case-control studies were identified on the association between 15 NOS3 gene variations and IRSA. However, significant inconsistencies exist in the selection criteria of patients and controls between studies. The meta-analysis of VNTR in intron 4 was performed on five studies (894 patients, 944 controls), whereas the meta-analysis of +894 G/T SNP included six studies (1111 patients, 1121 controls). The association with IRSA was significant for the +894 G/T SNP under the dominant genetic model (GT+TT versus GG) based on fixed (odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.28-1.86, P = <0.01) and random effects models (OR = 1.54, 95% CI = 1.03-2.31, P = 0.03). In conclusion, the GT and TT genotypes of the +894 G/T SNP in women might contribute to a predisposition to IRSA. Additional genetic association and functional studies in different populations with larger numbers of participants and a uniformly defined IRSA are needed to clarify the contribution of NOS3 +894 G/T gene variation to IRSA.

Ethnic differences in the association of thrombophilic polymorphisms with obstetric complications in Slovak and Roma (Gypsy) populations

AIMS

Hereditary as well as acquired thrombophilia is associated with a higher incidence of severe obstetric complications such as preeclampsia, spontaneous pregnancy loss, placental abruption, and fetal growth retardation. The aim of our study was to examine the association of selected thrombophilic polymorphisms (factor V Leiden, MTHFR C677T, and MTHFR A1298C) with pregnancy complications in the Slovak majority population and the Roma (Gypsy) ethnic population. The study included 354 women; 120 patients and 105 controls from the Slovak majority population, 50 patients and 79 controls from the Slovak Roma population. Genotyping was performed by the real-time polymerase chain reaction method using TaqMan(®) MGB probes.

RESULTS

A statistically significant higher frequency of factor V Leiden (p=0.001, odds ratio [OR]=5.9) and MTHFR C677T polymorphism (p=0.011, OR=1.7) was observed in the Slovak majority patient group compared to the control group. The incidence of MTHFR A1298C polymorphism between patients and controls did not differ significantly. None of the three polymorphisms studied was in association with pregnancy complications in the group of Roma women.

CONCLUSIONS

Our study has confirmed the variable distribution of selected thrombophilic polymorphisms in different ethnic groups as well as their various effects on the clinical phenotype.

Recent advances in thiol and sulfide reactive probes

Because of the biological relevance of thiols and sulfides such as cysteine, homocysteine, glutathione and hydrogen sulfide, their detection has attracted a great deal of research interest. Fluorescent probes are emerging as a new strategy for thiol and hydrogen sulfide analysis due to their high sensitivity, low cost, and ability to detect and image thiols in biological samples. In this short review, we have summarized recent advances in the development of thiol and hydrogen sulfide reactive fluorescent probes. These probes are compared and contrasted with regard to their designing strategies, mechanisms, photophysical properties, and/or reaction kinetics. Biological applications of these probes are also discussed.

Role of nitric oxide synthase genes in hepatitis E virus infection

Hepatitis E virus (HEV) is the most common cause of endemic and epidemic acute hepatitis. A correlation between iNOS, eNOS polymorphisms, levels and severity of disease has been reported, and here, we examined the role of iNOS and eNOS gene polymorphisms and their levels in HEV-related acute viral hepatitis and acute liver failure. Hepatitis E virus-related cases of acute hepatitis (294 patients) and liver failure (82 patients) and age- and sex-matched healthy controls (331 subjects) were included in the study. PCR-RFLP was performed to identify the polymorphisms in the iNOS and eNOS genes. iNOS and eNOS levels were studied using ELISA assays and HEV viral load, genotype and combined effects of iNOS genotype, levels and parameters for disease severity were examined. The frequency of iNOS (CT + TT) and eNOS (GT + TT) genotypes was higher in subjects with liver failure compared with controls. iNOS and eNOS levels in patients with acute liver failure (55.51 ± 6.33 IU/mL, 60.2 ± 3.69) cases were significantly increased as compared to patients with acute viral hepatitis (17.8 ± 6.08 IU/mL, 23.7 ± 6.57) and controls (P < 0.05). A significant positive correlation was observed between the iNOS and eNOS levels in our study population when compared with the severity of disease parameters. Hence, the iNOS C150T polymorphism and the eNOS G894T polymorphism and high levels of iNOS and eNOS are associated with an increased risk of HEV-related acute hepatitis and liver failure. This study supports the possible role of nitric oxide synthase genes (iNOS and eNOS) in determining the severity of HEV infection.

Recurrent pregnancy loss in polycystic ovary syndrome: role of hyperhomocysteinemia and insulin resistance

Recurrent pregnancy loss (RPL) in polycystic ovary syndrome (PCOS), which occurs in ∼50% of total pregnancies is a frequent obstetric complication. Among the several hypotheses, insulin resistance (IR), obesity and hyperhomocysteinemia (HHcy) play significant role/s in RPL. This study was conducted to assess the link between elevated levels of homocysteine and IR in PCOS-associated women with RPL in Kolkata, India. A retrospective study was conducted of one hundred and twenty six PCOS women (<30 years) who experienced two or more spontaneous abortions during the first trimester presenting to Institute of Reproductive Medicine (IRM) in Kolkata during the period of March 2008 through February 2011. One hundred and seventeen non-PCOS subjects with matching age range were randomly chosen as controls. Incidence of HHcy and IR was 70.63% (n = 89) and 56.34% (n = 71), respectively, in RPL-affected PCOS population which was significantly higher (p<0.04; p<0.0001) when compared to the non-PCOS set (HHcy: 57.26%; IR: 6.83%). Rates of miscarriage were significantly higher (p<0.008; p<0.03) in hyperhomocysteinemia-induced miscarriage when compared to the normohomocysteinemic segment (PCOS: 70.63% vs.29.36% & non-PCOS: 57.26% vs. 42.73%) along with the insulin resistant (p<0.04; p<0.0001) population (PCOS: 70.63% vs. 56.34% & non-PCOS: 57.26% vs. 6.83%) in both groups. A probabilistic causal model evaluated HHcy as the strongest plausible factor for diagnosis of RPL. A probability percentage of 43.32% in the cases of HHcy- mediated RPL suggests its increased tendency when compared to IR mediated miscarriage (37.29%), further supported by ROC-AUC (HHcy: 0.778vs. IR: 0.601) values. Greater susceptibility towards HHcy may increase the incidence for miscarriage in women in India and highlights the need to combat the condition in RPL control programs in the subcontinent.

Association study between methylenetetrahydrofolate reductase polymorphisms and unexplained recurrent pregnancy loss: a meta-analysis

BACKGROUND

Recurrent pregnancy loss is an important clinical problem. Recently, high-level homocysteine in blood has been considered as a possible cause. Genetic polymorphisms in methylenetetrahydrofolate reductase (MTHFR) have been proved to be the common hereditary factors of high-level homocysteine. The association between MTHFR polymorphisms and unexplained recurrent pregnancy loss (URPL) has been reported but with controversial results. The purpose of present study is to collect and analyze published available data, and evaluate the association between MTHFR polymorphisms and URPL.

METHODS

A meta-analysis was performed to examine the association between MTHFR polymorphisms (C677T and A1298C) and URPL. Odds ratio (OR) and its 95% confidence interval (CI) were used in each study of genotype and allele contrast.

RESULT(S)

MTHFR C677T: The analysis included 3559 URPL cases and 5097 healthy controls. Overall random-effects odds ratios (ORs) were 1.68 (95% CI, 1.32-2.13; P<0.0001) for TT versus total genotypes, 1.35 (95% CI, 1.04-1.76; P=0.0224) for TT and CT genotype combined versus total genotypes and 1.34 (95%CI, 1.13-1.58; P<0.0001) for T versus total alleles. Although significant heterogeneity was found in C677T, it became weaker in the East Asian subgroup and the mixed subgroup when separated by ethnic subgroups. The results showed significant association between MTHFR C677T and URPL in the East Asian subgroup (ORs 2.11 for TT versus total genotype (P=0.0004) and 1.53 for T versus total alleles (P<0.0001)) and in the mixed subgroup (ORs 3.47 for TT versus total genotypes (P<0.0001) and 1.80 for T versus total alleles (P<0.027)), but not in Caucasian subgroup. MTHFR A1298C: The study involved 1163 URPL cases and 1061 healthy controls. Overall random-effects odds ratios (ORs) were 1.37 (95% CI, 0.71-2.67; P=0.3456) for CC versus total genotypes, 1.16 (95%CI, 0.98-1.38; P=0.0833) for CC+AC versus total genotypes and 1.04 (95%CI, 0.84-1.29; P=0.7112) for C versus total alleles. No significant association between MTHFR A1298C polymorphism and URPL was found.

CONCLUSIONS

These results indicate a significant association between MTHFR C677T mutation and URPL in the East Asian subgroup and mixed subgroup, but no significance in MTHFR A1298C mutation.

Association of kinase insert domain-containing receptor (KDR) gene polymorphisms with idiopathic recurrent spontaneous abortion in Korean women

OBJECTIVE

To investigate whether kinase insert domain-containing receptor (KDR) gene polymorphisms are risk factors for recurrent spontaneous abortion (RSA) in Korean women.

DESIGN

Case-control study.

SETTING

University hospital.

PATIENT(S)

Three hundred twenty-seven idiopathic RSA patients and 230 controls with Korean ethnicity.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The KDR -604T→C (rs2071559), 1192G→A (rs2305948), and 1719A→T (rs1870377) polymorphisms were assessed.

RESULT(S)

KDR -604TC and TC+CC genotypes were more prevalent in RSA patients than in controls (adjusted odds ratio [AOR] = 2.091 and 2.076, respectively). KDR -604TC+CC/1192GG, -604TC+CC/1719AA, and -604TC+CC/1719TA+TT combined genotypes exhibited higher frequencies in RSA patients (AOR = 2.422, 2.611, and 2.216, respectively). KDR -604C/1192G/1719A, -604C/1192G/1719T, -604C/1192G, -604C/1719A, and -604C/1719T haplotype frequencies were higher in RSA patients (OR = 1.778, 2.659, 2.089, 1.678, and 1.806, respectively), whereas -604T/1192G/1719A, -604T/1192G, and -604T/1719A haplotype frequencies were lower in RSA patients (OR = 2.422, 2.611, and 2.216, respectively). No association was found between RSA and KDR 1192G→A or 1719A→T.

CONCLUSION(S)

An association between the KDR -604T→C polymorphism and RSA was found in Korean women. Carriers of the -604C variant allele were more frequent among RSA patients than among controls, suggesting that KDR -604C may confer RSA risk. The association of 1719A→T with RSA that was found in Taiwanese Han women was not observed in Korean women.

Maternal folate, alcohol and energy metabolism-related gene polymorphisms and the risk of recurrent pregnancy loss

Epidemiological studies have suggested that the condition of recurrent pregnancy loss (RPL) may be multifactorial, with both genetic predisposition and environmental factors potentially involved in its pathogenesis. The aim of this study is to elucidate the associations between maternal folate, alcohol and energy metabolism-related gene polymorphisms and the risk of RPL. This case–control study, which involved 116 cases with two or more instances of RPL and 306 fertile controls, was performed in the city of Sapporo, Japan. The associations between eight single nucleotide polymorphisms of folate, alcohol and energy metabolism-related genes [methylenetetrahydrofolate reductase (MTHFR), 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR), alcohol dehydrogenase 1B (ADH1B), aldehyde dehydrogenase 2 (ALDH2), beta-3-adrenergic receptor (ADRB3) and peroxisome proliferator-activated receptor gamma (PPARG)], and RPL were assessed. Without consideration of cigarette smoking or alcohol use, the risk of RPL significantly decreased in women with the MTHFR rs1801133 TT, MTR rs1805087 AG or ALDH2 rs671 AA genotype (P < 0.05). The risk of RPL associated with cigarette smoking and alcohol use decreased significantly in women carrying the MTHFR rs1801133 T allele [odds ratio (OR), 0.51; 95% confidence interval (CI), 0.27–0.95]. Similarly, the risk of RPL significantly decreased in women carrying the MTR rs1805087 G allele (OR, 0.44; 95% CI, 0.23–0.85). Our findings suggest that maternal gene polymorphisms related to folate metabolism may decrease the risk of RPL. Molecular epidemiological studies are needed to unequivocally elucidate the multifactorial effects of both genetic and environmental factors on human fecundity.

Lack of Association between Recurrent Pregnancy Loss and Inherited Thrombophilia in a Group of Colombian Patients

Studies have shown an association between recurrent pregnancy loss and inherited thrombophilia in Caucasian populations, but there is insufficient knowledge concerning triethnic populations such as the Colombian. The aim of this study was to evaluate whether inherited thrombophilia is associated with recurrent pregnancy loss. Methods. We conducted a case-control study of 93 patients with recurrent pregnancy loss (cases) and 206 healthy multiparous women (controls) in a Colombian subpopulation. Three single nucleotide polymorphisms (SNPs) markers of the inherited thrombophilias factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T were genotyped by PCR-RFLP. Activated protein C resistance and plasma levels of antithrombin, protein C, and protein S were also measured. Results. The frequency of thrombophilia-associated SNPs, activated protein C resistance, and anticoagulant protein deficiencies, was low overall, except for the methylenetetrahydrofolate reductase C677T SNP. The differences between patients and controls had no statistical significance. Conclusion. Our study confirms the low prevalence of inherited thrombophilias in non-Caucasian populations and it is unlikely that the tested thrombophilias play a role in the pathogenesis of recurrent pregnancy loss in this Colombian population.

p53 codon 72 polymorphism and recurrent pregnancy loss: a meta-analysis

BACKGROUND

Arg72Pro polymorphism of the p53 tumour suppressor gene have been associated with recurrent pregnancy loss. However, results were inconsistent. We performed this metaanalysis to drive amore precise estimation of association between p53 codon 72 polymorphism and recurrent pregnancy loss.

METHODS

Electronic searche of PubMed was conducted to select studies. Case-control studies containing available genotype frequencies of Arg72Pro were chose, and Odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association.

RESULTS

4 case-control studies including 523 cases and 378controls were identified. This meta-analysis showed that individuals with the homozygous Pro/Pro genotype had increased risk of recurrent pregnancy loss (OR = 1.85, 95% CI: 1.078 ~ 3.173, p = 0.025) in the pooled analyses. An symmetric funnel plot, the Egger's test (P = 0.497), and the Begg- test (P = 0.85) were all suggestive of the lack of publication bias.

CONCLUSION

This meta-analysis supports the idea that p53 condon72 Pro/Pro genotype is associated with increased risk of recurrent pregnancy loss. To draw comprehensive and true conclusions, further prospective studies with larger numbers of participants worldwide are needed to examine associations between p53 codon 72 polymorphism and recurrent pregnancy loss.

Genetic association studies of angiogenesis- and vasoconstriction-related genes in women with recurrent pregnancy loss: a systematic review and meta-analysis

BACKGROUND

Angiogenesis and an adequate blood supply are critical for several steps in human early pregnancy. Some studies have reported angiogenesis- and vasoconstriction-related genes are associated with recurrent pregnancy loss (RPL), but their sample size was limited. This study was conducted to investigate the genetic association between these angiogenesis- and vasoconstriction-related genes and idiopathic RPL, using meta-analyses.

METHODS

A systematic review of the published literature from MEDLINE and EMBASE databases was conducted and investigations of an angiogenesis- and vasoconstriction-related gene polymorphism in RPL reported more than three times were selected. Aggregating data from eligible studies were integrated into meta-analyses by means of random effects models.

RESULTS

Of 185 potentially relevant studies, 18 case-control studies comprising a total of 2397 RPL patients and 1760 controls were included into the meta-analyses. Among these genetic association studies were 4 reports of vascular endothelial growth factor (VEGF) (-1154G>A) polymorphisms, 4 reports of p53 (codon72) and 10 reports of endothelial nitric oxide synthase (eNOS) (B/A, Glu298Asp) with RPL. The integrated results showed that VEGF (-1154G>A), p53 (codon 72) and eNOS (Glu298Asp) polymorphisms were significantly associated with RPL, and their summary odd ratios [95% confidence interval (CI)] were 1.51 (1.13-2.03), 1.84(1.07-3.16) and 1.37 (1.11-1.69), respectively. The summary odd ratio of the eNOS (B/A) polymorphism in RPL was 1.15 (0.94-1.41), and failed to show significance at meta-analysis.

CONCLUSIONS

Meta-analyses of available data showed significant associations between the VEGF (-1154G>A), p53 (codon72) and eNOS (Glu298Asp) polymorphisms and idiopathic RPL. These angiogenesis- and vasoconstriction-related genes jointly confer higher susceptibility to idiopathic RPL.

Role of uterine artery Doppler velocimetry indices and plasma adrenomedullin level in women with unexplained recurrent pregnancy loss

AIM

To evaluate uterine artery Doppler flow resistance and plasma adrenomedullin levels in women with unexplained recurrent pregnancy loss (RPL) compared to controls.

MATERIAL & METHODS

Eighty-three women, who attend the department of Obstetrics and Gynecology, Benha University, Egypt, participated in this study (RPL group: n=40, and control group: n=43). Uterine artery Doppler and plasma adrenomedullin (AM) (pg/mL) levels were measured for all women in the mid-luteal phase of a non-pregnant cycle.

RESULTS

Both uterine artery pulsatility index (PI) and AM levels were significantly higher in RPL group compared to controls (2.71 ± 0.259 vs 2.06 ± 0.194 for PI and 287.5 ± 80.4 pg/mL vs 156.1 ± 39.8 pg/mL for AM, P<0.01). Uterine artery PI had a significant positive correlation with plasma AM levels both in the RPL group (r=0.645, P<0.001) and in the control group (r=0.384, P=0.011). Number of previous miscarriages in RPL group was significantly correlated with both uterine artery PI (r=0.838, P=0.015) and plasma AM levels (r=0.509, P=0.001).

CONCLUSIONS

Uterine artery PI may be useful in identifying women with unexplained RPL who have impaired uterine circulation. Plasma AM may serve as a biochemical marker for RPL caused by impaired uterine perfusion.

Nitric oxide platelet production in spontaneous miscarriage in the first trimester

OBJECTIVE

To investigate the role played by platelet nitric oxide (NO) metabolism in patients with spontaneous miscarriage (SM) and recurrent spontaneous miscarriage (RSM) compared with healthy pregnant women.

DESIGN

Retrospective case-control study.

SETTING

Patients and controls in an academic research environment.

INTERVENTION(S)

None.

PATIENT(S)

Thirty singleton pregnant women who experienced SM, nine singleton pregnant women who presented with RSM, and 30 singleton healthy pregnant women matched for age, parity, and gestational age were enrolled.

MAIN OUTCOME MEASURE(S)

NO levels and peroxynitrite (ONOO(-)) production; moreover, inducible NO synthase (iNOS), endothelial NO synthase (eNOS), and nitrotyrosine expression (N-Tyr) were observed in the same samples.

RESULT(S)

A significant increase was shown in platelet NO and ONOO(-) levels and in iNOS and N-Tyr both in SM and in RSM pregnant women compared with controls.

CONCLUSION(S)

The data herein reported imply that a modified NO pathway might play a key role in the physiological changes of advancing gestation but may also contribute to the pathophysiology of spontaneous miscarriage. Thus, any factors balancing NO metabolism might be useful in the treatment of miscarriage, thus reducing the substantial morbidity and associated mortality.

Recurrent pregnancy loss and thrombophilia

Emerging data seem to be available also on the role of active thromboprophylaxis with heparin and pregnancy outcome. In the last decades we found many data concerning the association between a hypercoagulable state and its causes and adverse pregnancy outcome, in particular recurrent pregnancy loss (RPL). First studies which focused on the association between thrombophilia and RPL underlined the role of reduced clotting inhibitors and RPL, and subsequent studies underlined a pathogenetic role of gene variant associated to hypercoagulable state in the occurrence of RPL. On the other hand, acquired thrombophilic abnormalities as antiphipsholipid syndrome are a well known cause of RPL and should be considered for a screening. These data are relevant because recent studies suggested a role of an extensive thromprophilaxis in women with RPL that should be addressed only in case of known thrombophilia and high risk of venous thromboembolism.

Anticoagulant therapy and pregnancy

Low dose aspirin therapy is one of the anticoagulant treatments used during pregnancy. Anticoagulant agents may be useful for several disorders, such as recurrent miscarriage, pre-eclampsia, fetal growth restriction and infertility. However, it is unclear whether anticoagulant therapy can increase the live birth rate in all of these cases. Recent data suggest that a low-dose aspirin and heparin combination therapy is effective in the prevention of recurrent pregnancy loss in women with antiphospholipid syndrome. Thrombogenic diseases, for example, protein C deficiency, protein S deficiency, factor XII deficiency and hyperhomocysteinemia, may cause pregnancy loss. The etiology of recurrent miscarriage is often unclear and may be multifactorial, with much controversy regarding diagnosis and treatment. Although 70% of recurrent pregnancy losses are unexplained, anticoagulant therapy is effective in maintaining pregnancy without antiphospholipid antibody syndrome. We conclude that a low-dose aspirin and heparin combination therapy can be useful for unexplained cases of recurrent pregnancy loss without antiphospholipid antibody syndrome. (Reprod Med Biol 2008; 7: 1-10).

Hyperhomocysteinemia in women with unexplained sterility or recurrent early pregnancy loss from Southern Italy: a preliminary report

Background

Hyperhomocysteinemia has been described as a risk factor for unexplained recurrent pregnancy loss. Increased levels of homocysteine may be due to inadequate dietary intake of folate and vitamin B12 and inherited defects within the methionine-homocysteine pathway such as MTHFR C677T gene polymorphism. However, the association between hyperhomocysteinemia and sterility problems have been underlined only for recurrent pregnancy loss while a relationship between hyperhomocysteinemia and female sterility is still matter of discussion.

Aim

This study sought to find out a possible relationship between sterility (primary sterility or secondary sterility due to recurrent pregnancy loss) and homocysteine metabolism.

Patients and Methods

We selected 20 patients with recurrent pregnancy loss, 20 patients with unexplained female sterility and 20 healthy women as control group. Several whole blood samples were collected by venipuncture. Firstly homocysteinemia and other related variables were tested (i.e. folate and vitamin B12 levels); thereafter DNA was extracted by a further whole blood sample collected in EDTA in order to screen MTHFR C677T gene polymorphism. Statistical analysis was performed by chi square test; differences were considered to be significant if p < 0.05.

Results

The median fasting total plasma homocysteine concentration was 19.2 ± 6.14 μM for patients with recurrent pregnancy loss, while was 21.05 ± 8.78 μM for patients with unexplained sterility, vs 7.85 ± 3.31 μM of control group (p < 0.05). Fifteen patients with unexplained female sterility showed MTHFR C677T homozigosity vs 17 with recurrent pregnancy loss and 3 in the control group (p < 0.05). On the other hand no significant differences were found in the levels of vitamin B 12 in the three groups, while reduced folate concentrations were found in women with unexplained female sterility and recurrent pregnancy loss (p < 0.05 vs control group.

Discussion

MTHFR C677T gene polymorphism is frequent in the studied populations. These data raise questions on the role of the homocysteine metabolism in sterility problems. Even though increased homocysteine (i.e. > 15 μM) and MTHFR C677T homozigosity have already been described as risk factors for recurrent pregnancy loss, few studies evaluated their role in women with unexplained sterility. Further studies on larger series are needed to better understand the role of homocysteine metabolism, including folate metabolism, in this clinical setting.

Methylenetetrahydrofolate reductase C677T polymorphism and the risk of unexplained recurrent pregnancy loss: a meta-analysis

OBJECTIVE

To investigate the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of unexplained recurrent pregnancy loss (URPL).

DESIGN

Meta-analysis of published case-control studies of the MTHFR C677T variant and URPL risk.

SETTING

A research institution in China.

PATIENT(S)

Women with URPL.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Odds ratios (ORs) and 95% confidence intervals (CIs) for TT versus CC genotype, CT versus CC genotype, TT versus CT and CC genotype combined, and for T versus C allele.

RESULT(S)

Twenty-six studies with 2120 URPL cases and 2949 controls were included. Overall random-effects ORs of 1.49 (95% CI, 1.12-2.00) for TT versus CC genotype, 1.40 (95% CI, 1.11-1.77) for TT versus CT and CC genotype combined, and 1.21 (95%CI, 1.04-1.40) for T versus C allele were found. Stratified analysis showed that significant strong associations between MTHFR C677T polymorphism and URPL were present only in the five Chinese studies (OR = 2.96 for TT versus CC genotype; OR = 2.30 for TT versus CT+CC genotype; OR = 1.73 for T versus C allele), but not in any other studies, including the studies conducted in the European countries.

CONCLUSION(S)

The MTHFR C677T mutation is not a genetic risk factor for URPL except in a Chinese population.

Methylenetetrahydrofolate reductase C677T and A1298C polymorphism and changes in homocysteine concentrations in women with idiopathic recurrent pregnancy losses

Because they have been described as strong risk factors for idiopathic recurrent pregnancy losses (RPLs), we assessed the association between the methylenetetrahydrofolate reductase (MTHFR) single-nucleotide polymorphisms (SNPs) C677T and A1298C and hyperhomocysteinemia in Tunisian women with idiopathic RPL. Study subjects comprised 200 patients with more than three consecutive RPLs, and 200 age-matched parous control women. C677T and A1298C SNPs were analyzed by PCR-RFLP analysis, and fasting serum homocysteine was measured with ELISA. The frequency of MTHFR 677T/T (30.0 vs 7.0%) and 1298C/C (13.5 vs 4.0%) genotypes was significantly higher in patients. While it was similar among patients and controls (P = 0.095), higher homocysteine was seen with the T/T (but not 1298A/C and 1298C/C) genotype among patients and controls compared with non-T/T carriers (P < 0.05), and in patients vs controls. Higher prevalence of MTHFR 677T/T was seen in late (P < 0.05) and early-late (P < 0.001) RPL, while higher prevalence of 1298C/C genotype was seen only in early-late RPL (P < 0.001), and the prevalence of double heterozygotes was statistically not significant between patients and controls (P = 0.10; odds ratio = 2.73). Logistic regression analysis showed that, after adjusting for all variables, homozygosity for MTHFR C677T was associated with late (P < 0.001), and combined early-late (P < 0.001), while homozygosity for A1298C was associated only with combined early-late (P = 0.026), as was secondary-level education, which was associated with early (P = 0.005), late (P = 0.026) and combined early-late (P = 0.004) abortions. Homozygosity for MTHFR C677T (late and early-late) and A1298C (early-late) are risk factor for RPLs, irrespectively of total homocysteine levels.

Maternal methylenetetrahydrofolate reductase deficiency and low dietary folate lead to adverse reproductive outcomes and congenital heart defects in mice

BACKGROUND

Genetic or nutritional disturbances in folate metabolism may affect embryonic development because of the critical role of folate in nucleotide synthesis and methylation reactions. The possible role of a mild deficiency in methylenetetrahydrofolate reductase (MTHFR) and low dietary folate in pregnancy outcomes and heart morphogenesis requires further investigation.

OBJECTIVE

We investigated the effect of mild MTHFR deficiency, low dietary folate, or both on resorption rates, on length and weight, and on the incidence of heart malformations in murine embryos.

DESIGN

Female Mthfr +/+ and +/- mice were fed a control diet (CD) or a folic acid-deficient diet (FADD) before mating with male Mthfr +/- mice. On gestational day 14.5, implantation and resorption sites were recorded and viable embryos were examined for gross malformations, growth delay, and congenital heart defects.

RESULTS

Plasma homocysteine in Mthfr +/- dams and in FADD-treated dams was significantly higher than that in Mthfr +/+ dams and CD-treated dams, respectively. A significantly higher rate of resorption and greater developmental delay were observed in hyperhomocysteinemic mice than in CD-treated +/+ dams. Heart defects were identified in 4 of 11, 5 of 10, and 4 of 10 litters from CD-treated +/-, FADD-treated +/+, and FADD-treated +/- dams, respectively, but not in any of those from CD-treated +/+ dams (0/11 litters).

CONCLUSION

Our findings suggest that mild MTHFR deficiency, low dietary folate, or both in the dams increase the incidence of fetal loss, intrauterine growth retardation, and heart defects. These data support the benefit of folic acid supplementation in pregnant women, particularly in those with MTHFR deficiency.