Low chorionic villous succinate accumulation associates with recurrent spontaneous abortion risk.

Dysregulated extravillous trophoblast invasion and proliferation are known to increase the risk of recurrent spontaneous abortion (RSA); however, the underlying mechanism remains unclear. Herein, in our retrospective observational case-control study we show that villous samples from RSA patients, compared to healthy controls, display reduced succinate dehydrogenase complex iron sulfur subunit (SDHB) DNA methylation, elevated SDHB expression, and reduced succinate levels, indicating that low succinate levels correlate with RSA. Moreover, we find high succinate levels in early pregnant women are correlated with successful embryo implantation. SDHB promoter methylation recruited MBD1 and excluded c-Fos, inactivating SDHB expression and causing intracellular succinate accumulation which mimicked hypoxia in extravillous trophoblasts cell lines JEG3 and HTR8 via the PHD2-VHL-HIF-1α pathway; however, low succinate levels reversed this effect and increased the risk of abortion in mouse model. This study reveals that abnormal metabolite levels inhibit extravillous trophoblast function and highlights an approach for RSA intervention.

Iodothyronine deiodinase 2 (DiO2) regulates trophoblast cell line cycle, invasion and apoptosis; and its downregulation is associated with early recurrent miscarriage.

INTRODUCTION: Trophoblast development is a crucial event in placentation and pregnancy complications but its underlying mechanisms remain unclear. Thus, we aimed at investigating the role of DiO2 in trophoblast cell line decisions and assessing its placental villous expression in early recurrent miscarriage (ERM) patients. METHODS: The placental villous expression of DiO2 was determined with immunofluorescence. Cell proliferation was measured with the CCK8 kit while cell-cycle and apoptosis were studied with flow-cytometry. Cell migration and invasion were measured with wound-healing and transwell assays, respectively. Gene expression was then assessed with RT-qPCR and western blotting. RESULTS: DiO2 is expressed in the CTB, PCT, DCT and STB of the placenta. Its overexpression arrested trophoblast cell line proliferation at the G1 phase of the cell-cycle by downregulating cyclin-D1 and PCNA, while promoting apoptosis via increased caspase-3 activity and inhibition of the AKT and ERK1/2 signaling pathways. Also, it augmented trophoblast cell line migration and invasion via the upregulation of N-cadherin, vimentin, fascin-1, twist-1 and other epithelial-mesenchymal transition genes. DiO2 knockdown elicited the opposite effects. Surprisingly, each of these effects of DiO2 manipulation was not mediated by thyroid hormone metabolism. Assessment of the ERM placental villi revealed a downregulation of DiO2, N-cadherin, vimentin, fascin-1 and twist-1. The expression of E-cadherin remained unchanged in these placentae. DISCUSSION: During placentation, DiO2 may inhibit trophoblast proliferation while facilitating their differentiation into an invasive phenotype; and that its downregulation may contribute to the shallow trophoblast invasion that precedes ERM. Hence, DiO2 is a potential therapeutic target against ERM.

Effect of the IDO Gene on Pregnancy in Mice with Recurrent Pregnancy Loss.

The aim of this study is to investigate the effect of the IDO (indoleamine 2,3-dioxygenase) gene on pregnancy outcome in mice with recurrent pregnancy loss (RPL) and its mechanism of action in the maternal-fetal interface. An RPL model was established via natural mating of female CBA/J mice with male DBA/2 mice; thereafter, the female mice were randomly divided into groups treated with LV-EGFP (enhanced green fluorescent protein)-IDO (lentivirus vector carrying IDO-EGFP gene), LV-EGFP (negative control lentivirus vector), or phosphate-buffered saline (control). The mice were sacrificed at 13.5 days of pregnancy, and the embryo absorption rate was determined. Peripheral blood regulatory T cells (Tregs) from the pregnant mice were detected using flow cytometry. Placental and decidual tissue IDO expression was detected using immunofluorescence and Western blotting. Inflammatory cell infiltration of the placental and decidual tissue was observed using hematoxylin-eosin (HE) staining. The LV-EGFP-IDO group had a significantly lower embryo absorption rate than the LV-EGFP and control groups (P = 0.0006 and P = 0.0049, respectively) and significantly more Tregs than the LV-EGFP and control groups (P = 0.0151 and P = 0.0392, respectively). Placental and decidual IDO protein levels correlated positively with peripheral blood Treg expression levels. The LV-EGFP-IDO group had significantly higher placental and decidual IDO protein levels than the LV-EGFP and control groups (P < 0.005), and it had significantly less inflammatory cell infiltration than the LV-EGFP and control groups. The IDO gene may reduce the embryo absorption rate in an RPL mouse model, possibly improving pregnancy outcome by upregulating Tregs and reducing the inflammatory response.

Abnormal Expression of Indoleamine 2, 3-Dioxygenase in Human Recurrent Miscarriage.

Indoleamine 2, 3-dioxygenase (IDO), an immunosuppressive enzyme that mediates the conversion of tryptophan to kynurenine, was shown to play a key role in placental development during normal pregnancy. However, little is known about the pattern of IDO expression in the endometrium and its attendant functional significance in pregnancies complicated with recurrent miscarriage (RM). Immunohistochemical studies of IDO, Foxp3, CD56, and CD163 expression were performed in endometrial samples from women with RM and healthy fertile controls. Our study found that IDO was localized in glandular epithelial cells, surface epithelial cells, and a small number of cells within the stromal compartment (including stromal cells and leukocytes) in endometrium. Indoleamine 2, 3-dioxygenase expression in the RM group was significantly lower than control group. The Foxp3 and CD56 expression were significantly increased with the elevated IDO expression in controls but not in RM. The percentage of Foxp3 + Tregs was significantly correlated with the level of IDO expression in the control group. Comparatively, no correlation was found between the percentage of CD56 + cells, CD163 + cells, and the level of IDO expression, no matter in controls and RM patients. This study demonstrated that the downregulation of IDO expression and noncoordinated association between IDO and other endometrial immune cells were associated with RM. Our findings provide insights into the contribution of IDO in immune regulation to maintain normal pregnancy, which could be used to develop potential therapeutic methods for RM.

Paraoxonase-1 Polymorphisms (L55M/Q192R) and Activities (PONase/AREase) in Patients with Idiopathic Recurrent Early Pregnancy Loss: A Preliminary Study.

Aim: To evaluate the associations between idiopathic recurrent early pregnancy loss (REPL) and paraoxonase-1 (PON1) polymorphisms and the activities of its encoded enzymes. Materials and Methods: Ninety-eight women were enrolled in this study, including 21 currently pregnant multiparous women without a history of miscarriage; 18 multiparous women who were not pregnant during the study; 30 women with a history of idiopathic REPL who were pregnant; and 29 who were not. Paraoxonase (PONase) and arylesterase (AREase) activities, two activities of the PON1 enzyme, were measured through commercially available kits (Relassay, Gaziantep, Turkey). PON1 genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. Data were analyzed using SPSS for Windows version 19.0 (SPSS). Results: There was no association between idiopathic REPL and PON1 polymorphisms or PONase activity. The AREase activity of the PON1 enzyme trended higher in the healthy pregnant group than in the healthy nonpregnant group (p = 0.067), and was higher in the pregnant group with a history of idiopathic REPL than in the nonpregnant group with a history of idiopathic REPL (p = 0.041). Conclusions: Despite there being no detected association between PON1 activities or genotype and idiopathic REPL, we showed that AREase activity increased during early gestation. New studies, including longitudinal changes in serum AREase activity throughout normal pregnancy, should be carried out to further evaluate the association between PON encoded enzymatic activities and early gestational pathophysiology.

Relationship between unexplained recurrent pregnancy loss and 5,10-methylenetetrahydrofolate reductase) polymorphisms.

OBJECTIVE: To investigate the relationship between unexplained recurrent pregnancy loss (URPL) and polymorphisms of folate metabolism-related genes. DESIGN: A case-control study. SETTING: Urban university-based hospital. PATIENT(S): Two-hundred and eighteen women with URPL and 264 healthy controls. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Fluorescence quantitative polymerase chain reaction examination of sequences of the C677T and A1298C loci of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene. RESULT(S): The frequency of the T allele at the MTHFR C677T locus in the URPL group was statistically significantly higher compared with the control group (odds ratio [OR] 1.324; 95% confidence interval [CI], 1.014-1.729), and the presence of the CC+CT genotype was statistically significantly reduced in the URPL group (OR 0.678; 95% CI, 0.471-0.974). The frequency of the C allele at the MTHFR A1298C locus in the URPL group was statistically significantly higher than that in the control group (OR 1.557; 95% CI, 1.066-2.275), and the presence of the CC+AC genotype was statistically significantly elevated in the URPL group (OR 1.740; 95% CI, 1.137-2.661). The frequency of MTHFR 677CT/1298AC compound genotypes in the URPL group was 6.589-fold higher compared with the control group. Most patients in the URPL group carried two mutant genes (69.3%), and the percentage of patients with two mutant genes was statistically significantly higher than in the control group (OR 4.996; 95% CI, 1.650-15.129). CONCLUSION(S): The MTHFR 1298AC genotype and composite heterozygote genotype (677CT/1298AC) are risk factors for URPL. The risk of URPL is highest in women carrying two mutations of A1298C and C677T locus in MTHFR.

Evaluation of iNOS -2087A>G polymorphism in recurrent pregnancy loss.

BACKGROUND: Due to its role in angiogenesis, the inducible nitric oxide synthase (iNOS) gene promoter polymorphism may have a presumed role in recurrent spontaneous abortions (RSA). It is an intensely studied protein, a biological mediator, a modulator and an effector molecule by implication in numerous physiological processes: vasodilatation, angiogenesis, immunity, tissue remodeling, smooth muscle activity. AIM: Our study aims to investigate a possible association between iNOS -2087A>G (rs2297518) polymorphism and the occurrence of idiopathic recurrent pregnancy loss (RPL). PATIENTS, MATERIALS AND METHODS: In this study, as in the previously published one, 169 women, diagnosed with RPL, in the Clinics of Obstetrics and Gynecology, "Filantropia" Municipal Hospital, Craiova, Romania, were subjected to the analysis, from October 2009 to October 2016. As a control group, we used 145 women. Subjects from both groups were genotyped using specific probes for TaqMan polymerase chain reaction (PCR), allelic discrimination technique. RESULTS: We evaluated in this study a possible association between iNOS -2087A>G (rs2297518) polymorphism and the occurrence of idiopathic RPL. The chi-square test showed no significant association between the presence of this polymorphism and the increased risk to develop RPL. When we performed a comparative analysis of the frequency of genotypes and our statistical data, it was observed that this polymorphism, iNOS -2087A>G (rs2297518), has not been associated with an increased risk of developing RPL. Also, when one genotype was compared with another, we did not obtain any association that would have statistical significance, between the presence of this polymorphism and the increased risk for patients to develop RPL [in dominant - A allele carriers, iNOS 2087 AG+AA vs. GG: odds ratio (OR) 1.31, 95% confidence interval (CI) 0.83-2.07, p=0.24]. Analyzing the overall risk of developing RPL by iNOS 2087 single-nucleotide polymorphism (SNP) genotype frequencies, between controls and RPL patients (which were stratified by number of consecutive PLs), taking into account the number of consecutive pregnancies, the chi-square test showed no association between the presence of this polymorphism and the increased risk for developing RPL in all three subgroups we analyzed (in a dominant model - A allele carriers, iNOS 2087 AG+AA vs. GG: the first subgroup, OR 1.31, 95% CI 0.83-2.07, p=0.24; the second subgroup, OR 1.26, 95% CI 0.76-2.11, p=0.37; the three subgroup, OR 1.4, 95% CI 0.77-2.53, p=0.272). CONCLUSIONS: The iNOS -2087A>G (rs2297518) gene polymorphism does not influence RPL in the study area of Dolj County, Romania.

The association between maternal methylenetetrahydrofolate reductase C677T and A1298C polymorphism and birth defects and adverse pregnancy outcomes.

Published studies indicate the MTHFR C677T and A1298C polymorphisms are associated with abnormal homocysteine levels, which may cause various pregnancy complications and birth defects. However, the results obtained from different studies have been inconsistent. Therefore, this meta-analysis explores the association between MTHFR polymorphisms and birth defects and adverse pregnancy outcomes. The PubMed, ScienceDirect, Embase, and China Biology Medicine literature databases and ClinicalTrials were searched. Analyses of public bias, meta-regression, subgroups, and sensitivity were used to ensure the robustness of our results. MTHFR C677T was significantly associated with recurrent pregnancy loss in developing countries (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.20-1.50) but not in developed countries (OR, 0.87; 95% CI, 0.68-1.11). No significant relationship was found between MTHFR A1298C and recurrent pregnancy loss (OR, 1.04; 95% CI, 0.93-1.18). MTHFR C677T and A1298C were not associated with preeclampsia (OR, 1.06; 95% CI, 0.97-1.16 and OR, 1.16; 95% CI, 0.97-1.39, respectively), and C677T was not associated with placental abruption (OR, 1.03; 95% CI, 0.87-1.21), intrauterine growth retardation (OR, 1.02; 95% CI, 0.90-1.15), or congenital heart disease (OR, 1.05; 95% CI, 0.89-1.25). MTHFR C677T, but not A1298C, was associated with neural tube defects (OR, 1.24; 95% CI, 1.08-1.42) and Down syndrome (OR, 1.65; 95% CI, 1.39-1.95). CONCLUSION: Although MTHFR C677T and A1298C are significantly associated with some types of congenital defects and adverse pregnancy outcomes, the impact of these polymorphisms is moderate.

Low transcriptional activity of PON2 in recurrent abortion: A novel therapeutic agent?

OBJECTIVE: Oxidative stress has been reported to be associated with various pregnancy complications and to play key roles in many of them. An inadequate level of antioxidant defense may eventually lead to an early pregnancy loss. There is a lack of information about the roles of the PON2 and PON3 enzymes in the etiology of the cases of unexplained recurrent abortus. The aim of our study is to determine and present the data regarding the roles of these enzymes for the first time. MATERIALS AND METHODS: We measured the transcriptional levels of the PON2 and PON3 enzymes in the curettage materials obtained from the patients with unexplained recurrent abortus (n=25) and compared the results with those measured in the abortus materials from healthy pregnant women (n=50) who had undergone a voluntary abortion. The transcriptional activities of PON2 and PON3 enzymes were measured through quantification of their respective mRNAs by RT-qPCR assay. For each gene, 2-ΔCt replication values of the control and the patient groups were compared using the Student's t-test, and the p values were calculated thereafter. Fold-changes in the enzyme transcription levels were interpreted as up- or down-regulation. RESULTS: PON2 mRNA expressions were found to be highly decreased in the patient group (p=0.000002). PON3 transcription, when compared to the healthy pregnant women, was found to be down-regulated in the patient group; however, the difference was not statistically significant (p=0.69). CONCLUSIONS: In this study, we evaluated the expressional regulation of the PON2 and PON3 enzymes in unexplained recurrent abortus. Our results demonstrate for the first time that the expressions of PON2 and PON3 are down-regulated in the abortion specimens of the patients with recurrent miscarriage. Although both enzymes had low expression levels, the decrease in the transcriptional activity of PON2 revealed a high statistical significance. According to these results, it is rational to speculate that PON2 may be a novel therapeutic agent in the management of the cases with unexplained recurrent abortion.

Proteomics and bioinformatics analysis of altered protein expression in the placental villous tissue from early recurrent miscarriage patients.

INTRODUCTION: Recurrent miscarriage (RM) affects 5% of women, it has an adverse emotional impact on women. Because of the complexities of early development, the mechanism of recurrent miscarriage is still unclear. We hypothesized that abnormal placenta leads to early recurrent miscarriage (ERM). The aim of this study was to identify ERM associated factors in human placenta villous tissue using proteomics. Investigation of these differences in protein expression in parallel profiling is essential to understand the comprehensive pathophysiological mechanism underlying recurrent miscarriage (RM). METHODS: To gain more insight into mechanisms of recurrent miscarriage (RM), a comparative proteome profile of the human placenta villous tissue in normal and RM pregnancies was analyzed using iTRAQ technology and bioinformatics analysis used by Ingenuity Pathway Analysis (IPA) software. RESULTS: In this study, we employed an iTRAQ based proteomics analysis of four placental villous tissues from patients with early recurrent miscarriage (ERM) and four from normal pregnant women. Finally, we identified 2805 proteins and 79,998 peptides between patients with RM and normal matched group. Further analysis identified 314 differentially expressed proteins in placental villous tissue (≥1.3-fold, Student's t-test, p < 0.05); 209 proteins showed the increased expression while 105 proteins showed decreased expression. These 314 proteins were analyzed by Ingenuity Pathway Analysis (IPA) and were found to play important roles in the growth of embryo. Furthermore, network analysis show that Angiotensinogen (AGT), MAPK14 and Prothrombin (F2) are core factors in early embryonic development. We used another 8 independent samples (4 cases and 4 controls) to cross validation of the proteomic data. DISCUSSION: This study has identified several proteins that are associated with early development, these results may supply new insight into mechanisms behind recurrent miscarriage.

Comparison of two preventive treatments for patients with recurrent miscarriages carrying a C677T methylenetetrahydrofolate reductase mutation: 5-year experience.

Objective To investigate the effect of anticoagulant treatment on pregnancy outcomes in patients with previous recurrent miscarriages (RM) who carry a methylenetetrahydrofolate reductase ( MTHFR) gene mutation. Methods In this longitudinal retrospective study, patients with RM were treated during pregnancy with either: (i) 100 mg/day aspirin and 5 mg/day folic acid (group 1); or the same protocol plus 0.4 mg/day enoxaparin (group 2). An age-matched group of triparous women without RM or thrombophilia was used as the control group (group 3). Results This study enrolled 246 women with RM (123 per treatment group) and age-matched controls ( n = 117). The delivery rate was significantly lower in group 1 than group 2 (46.3% versus 79.7%, respectively). The miscarriage rate was significantly lower in group 2 compared with group 1 (20.3% versus 51.2%, respectively). In the control group 3, the delivery rate was 86.3% and the miscarriage rate was 12.8%. Conclusion Treatment with low-dose aspirin, enoxaparin and folic acid was the most effective therapy in women with RM who carried a C677T MTHFR mutation.

Maternal common variant rs2305957 spanning PLK4 is associated with blastocyst formation and early recurrent miscarriage.

OBJECTIVE: To investigate whether the common variant rs2305957 spanning PLK4 (Polo-like kinase 4) confers risk to embryo development in Northern Chinese Han (CHN) women. DESIGN: Genetic association study. SETTING: University hospital. PATIENT(S): A total of 2,015 infertile women who underwent in vitro fertilization (IVF), 530 women with early recurrent miscarriage (ERM), and 600 fertile control women in the CHN population. INTERVENTION(S): Genotyping of rs2305957 was performed by means of high-resolution melting analysis. MAIN OUTCOME MEASURE(S): Blastocyst formation, implantation, early miscarriage, and live birth rates in infertile women; genotype distribution at rs2305957 in ERM case and control subjects. RESULT(S): In the first cohort of this study, infertile women with AA genotype had a lower blastocyst formation rate than those with AG or GG genotype. No significant differences were observed in implantation rate, early miscarriage rate, or live birth rate among AA, AG, and GG subgroups. In the second cohort, common variant rs2305957 was related to ERM. Genotype frequency differences were also significant in both additive model and dominant model. CONCLUSION(S): Common variant rs2305957 is associated with blastocyst formation and ERM in CHN women. Further investigations of PLK4 gene during embryo development could be worthwhile.

Superoxide dismutase activity and gene expression levels in Saudi women with recurrent miscarriage.

The antioxidant activities of superoxide dismutase 1 (SOD1) and SOD2, as well as the levels of the oxidant superoxide anion (SOA) and the micronutrients zinc (Zn), copper (Cu) and manganese (Mn), were assayed in plasma, whole blood and placental tissue of non­pregnant (NP), healthy pregnant (HP) women and recurrent miscarriage (RM) patients. The results showed that SOD1 and SOD2 activities and the levels of Zn, Cu and Mn in plasma and whole blood of HP women were slightly, but significantly lower, and even more significantly decreased in RM patients compared to those observed in NP women (P<0.05 and P<0.0001, respectively). Additionally, whereas plasma SOD1 and SOD2 activities and Zn, Cu and Mn levels were significantly lower in RM patients, those of whole blood and placental tissue were significantly lower when compared to HP women (P<0.001 and P<0.0001, respectively). Concurrently, there were consistent increases of equal magnitude and statistical significance in SOA levels in all the assayed samples as identified by a comparison between the subjects. The findings thus supported oxidative metabolism and excessive reactive oxygen species generation. The resultant oxidative stress, identified in whole blood and placental tissues of RM patients, may have been a primary cause of RM. Dietary supplementation of Zn, Cu and Mn may be beneficial to these patients pre- and post-conception.

Methyltetrahydrofolate vs Folic Acid Supplementation in Idiopathic Recurrent Miscarriage with Respect to Methylenetetrahydrofolate Reductase C677T and A1298C Polymorphisms: A Randomized Controlled Trial.

PURPOSE: To determine whether 5-methylenetetrahydrofolate (MTHF) is more effective than folic acid supplementation in treatment of recurrent abortion in different MTHFR gene C677T and A1298C polymorphisms. METHODS: A randomized, double blind, placebo-controlled trial conducted April 2011-September 2014 in recurrent abortion clinics in Tehran, Iran. The participants were women with three or more idiopathic recurrent abortion, aged 20 to 45 years. Two hundred and twenty eligible women who consented to participate were randomly assigned to receive either folic acid or 5-MTHF according to the stratified blocked randomization by age and the number of previous abortions. Participants took daily 1 mg 5-methylentetrahydrofolate or 1 mg folic acid from at least 8 weeks before conception to the 20th week of the pregnancy. The primary outcome was ongoing pregnancy rate at 20th week of pregnancy, and the secondary outcomes were serum folate and homocysteine at the baseline, after 8 weeks, and at the gestational age of 4, 8, 12, and 20 weeks, MTHFR gene C677T and A1298C polymorphisms. RESULTS: There was no significant difference in abortion rate between two groups. Serum folate increased significantly in both groups over time; these changes were significantly higher in the group receiving 5-MTHF than the group receiving folic acid (value = 2.39, p<00.1) and the result was the same by considering the time (value = 1.24, p<0.01). Plasma tHcys decreased significantly in both groups over time; however these changes were not significantly different between the groups (value = 0.01, p = 0.47). CONCLUSION: The results do not support any beneficial effect of 5-MTHF vs. folate supplementation in women with recurrent abortion with any MTHFR C677T and/or A1298C polymorphism. TRIAL REGISTRATION: ClinicalTrials.gov NCT01976676.

Role of cathepsin E in decidual macrophage of patients with recurrent miscarriage.

In a previous study, we reported that the cathepsin-cystatin system caused endometrial dysfunction in early pregnancy. Here, we investigated the existence and contribution of cathepsin E in early pregnancy in patients with recurrent miscarriage (RM). The effect of cathepsin deficiency on fertility and female reproductive organs were also analyzed in CatE(-/-) mice. Human studies were conducted in a hospital setting, with informed consent. Cervical mucus was collected from RM patients in early pregnancy (4-6 gestational weeks, n = 21), and the pregnancy outcome was compared prospectively. The cathepsin E expression in decidua of RM patients (n = 49) and normal pregnant women undergoing elective surgical abortion (n = 24) was measured using SDS-PAGE, and western blot analysis. Decidual macrophages were isolated from RM patients (n = 6) and stimulated by lipopolysaccharide (LPS) and interferon gamma (IFN-γ). Results from the mouse model showed that CatE(-/-) mice were fertile, but the litter number was significantly smaller. The uterus of CatE(-/-) mice showed granulation tissue. In human samples, protease activity of cathepsin E measured with Fluorescence-Quenching Substrate (KYS-1) in cervical mucus of patients who developed miscarriage was markedly decreased compared with patients without RM. The expression of cathepsin E in decidua, semi-quantified by SDS-PAGE, western blot analysis was significantly lower in RM patients compared with patients without RM. By double staining immunofluorescence, the staining of cathepsin E was observed in CD14 or CD68 positive cells in all deciduas. Upon stimulation with LPS and IFN-γ, the expression of cathepsin E in cell lysate of decidual macrophages was markedly reduced in RM patients compared with controls. The results suggested that decreased activity of cathepsin E produced by decidual macrophages might be responsible for the induction of miscarriages in some RM patients.

Endothelial nitric oxide synthase gene variants and haplotypes associated with an increased risk of idiopathic recurrent miscarriage.

We investigated the association of endothelial nitric oxide synthase (NOS3) polymorphisms rs2070744 (-786T> C), 27-bp repeat 4b/4a, rs1799983 (Glu298Asp), rs3918188 (-734C> A), and rs743507 (113G> A) with idiopathic recurrent miscarriage (IRM). This was a case-control study involving women with confirmed IRM (n = 296), and 305 age- and ethnically matched control women. NOS3 rs2070744, rs1799983, rs3918188, and rs743507 genotyping was done by TaqMan assays; NOS3 4b/4a genotyping was done by PCR-ASA. A higher frequency of -786C and 298Asp alleles was seen in IRM cases, which remained associated independently with IRM on multivariate analysis. Allele and genotype distribution of 4b/4a, rs3918188 (-734C> A) and rs743507 (113A> G) were comparable between IRM cases and control women. Taking homozygous wild-type genotype as a reference, regression analysis confirmed the association of Glu298Asp and -786T/C, and rs743507 homozygous carriers with IRM risk. Marked linkage disequilibrium was seen between tested NOS3 variants, thus allowing the construction of 5-locus [-786T> C/4b4a/Glu298Asp/-734C> A/113G> A] haplotypes. Taking the common T4bGCA haplotype as a reference, multivariate analysis confirmed the positive association of C4bTCG haplotype with IRM, after controlling for traditional covariates. Genetic variation at the NOS3 locus represents a genetic risk factor for increased susceptibility to IRM.

Maternal factor V Leiden and prothrombin mutations do not seem to contribute to the occurrence of two or more than two consecutive miscarriages in Caucasian patients.

BACKGROUND: We analysed the prevalence of the most common hereditary thrombophilia (hTP) - factor V Leiden (FVL) mutation, prothrombin 20210 G>A substitution (PT) - and the 677 C>T replacement in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene in Caucasian patients with a history of two and more consecutive recurrent miscarriages (RMs) as compared to healthy controls with an identical ethnic background and at least one live birth. METHODS: A multicenter analysis of three hTP was performed in 641 RM patients identically screened at specialized university centres. RESULTS: The study groups consisted of 240 patients with 2 (1) and 401 patients with >2 miscarriages (2) and were compared with 157 controls. There was no significant difference in the prevalence of the hTP between RM patients and controls nor within the two study groups. Subgroup analysis showed that the homozygous MTHFR polymorphism was significantly more prevalent in the study group 2 as compared to study group 1 (13.9 versus 7.9%, P = 0.02). CONCLUSION: In Caucasians, maternal FVL or PT mutations do not seem to contribute to the pathophysiology of RM, irrespective of the number of miscarriages. However, the role of the homozygous MTHFR polymorphism merits further investigation.

Association of methionine synthase and thymidylate synthase genetic polymorphisms with idiopathic recurrent pregnancy loss.

OBJECTIVE: To investigate the association between one-carbon metabolism and recurrent pregnancy loss (RPL). One-carbon metabolism is important for maintaining pregnancy, and the enzymes codified by these genes are relevant to this metabolic pathway. DESIGN: Case-control study. SETTING: An urban university-based hospital in South Korea. PATIENT(S): A cohort of 353 RPL patients (3.09 ± 1.65 pregnancy losses) and 226 control subjects. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Genotyping was assessed by polymerase chain reaction-restriction fragment length polymorphism assay. We examined polymorphisms in four genes: methionine synthase (MTR); methionine synthase reductase (MTRR); methylenetetrahydrofolate dehydrogenase 1 (MTHFD1); and thymidylate synthase (TS). RESULT(S): The MTR 2756AA polymorphism was associated with RPL. Gene-gene interaction analysis revealed that the frequency of the MTR 2756A-TS 6-bp allele combination was significantly higher in RPL. CONCLUSION(S): Based on these results, we propose that the MTR 2756AA genotype and MTR 2756A-TS 6-bp allele combination are possible predisposing factors for RPL development in Korean women.

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.

Genetic association studies of ACE and PAI-1 genes in women with recurrent pregnancy loss: a systematic review and meta-analysis.

A fine balance between coagulation and fibrinolysis is critical in early pregnancy. Plasminogen activator inhibitor-1 (PAI-1) and angiotensin converting enzyme (ACE) are involved in the fibrinolytic process, and several studies have reported the association between their gene polymorphisms and recurrent pregnancy loss (RPL). This study was conducted to investigate the association between PAI-1 and ACE polymorphisms and idiopathic RPL, using meta-analyses. A systematic review of the published literature from the MEDLINE and EMBASE databases before April 2012 was conducted. Of 209 potentially relevant studies, 22 case-control studies comprising a total of 2,820 RPL patients and 3,009 controls were included. Among these studies were 11 reports of PAI-1 4G/5G and 11 of ACE I/D polymorphisms in patients with RPL. A significant association was found withthe ACE I/D polymorphism [summary odds ratio 1.29 (95% confidence interval 1.02-1.62)] in studies including more than two recurrent abortions. Subgroup analysis did not show significant associations with RPL in Caucasian and non-Caucasian patients. Meta-analyses of PAI-1 4G/5G polymorphism were not found associations with RPL in studies including more than two or three recurrent abortions, and in studies of Caucasian and non-Caucasian patients. In conclusion, meta-analyses showed a significant association between the ACE I/D polymorphism and idiopathic RPL. High clinical heterogeneity existed among studies of PAI-1 4G/5G, and the aggregated data failed to confer higher susceptibility to idiopathic RPL. More well-designed studies with different ethnic populations are required for future integration.