Polymorphisms of the angiotensinogen gene, the endothelial nitric oxide synthase gene, and the interleukin-1beta gene promoter in women with idiopathic recurrent miscarriage

BaP/BPDE exposure causes human trophoblast cell dysfunctions and induces miscarriage by up-regulating lnc-HZ06-regulated IL1B

Exposure to environmental BaP or its metabolite BPDE causes trophoblast cell dysfunctions to induce miscarriage (abnormal early embryo loss), which might be generally regulated by lncRNAs. IL1B, a critical inflammatory cytokine, is closely associated with adverse pregnancy outcomes. However, whether IL1B might cause dysfunctions of BaP/BPDE-exposed trophoblast cells to induce miscarriage, as well as its specific epigenetic regulatory mechanisms, is completely unexplored. In this study, we find that BPDE-DNA adducts, trophoblast cell dysfunctions, and miscarriage are closely associated. Moreover, we also identify a novel lnc-HZ06 and IL1B, both of which are highly expressed in BPDE-exposed trophoblast cells, in villous tissues of recurrent miscarriage patients, and in placental tissues of BaP-exposed mice with miscarriage. Both lnc-HZ06 and IL1B suppress trophoblast cell migration/invasion and increase apoptosis. In mechanism, lnc-HZ06 promotes STAT4-mediated IL1B mRNA transcription, enhances IL1B mRNA stability by promoting the formation of METTL3/HuR/IL1B mRNA ternary complex, and finally up-regulates IL1B expression levels. BPDE exposure promotes TBP-mediated lnc-HZ06 transcription, and thus up-regulates IL1B levels. Knockdown of either murine lnc-hz06 (which down-regulates Il1b levels) or murine Il1b could alleviate miscarriage in BaP-exposed mice. Collectively, this study not only discovers novel biological mechanisms and pathogenesis of unexplained miscarriage but also provides novel potential targets for treatment against BaP/BPDE-induced miscarriage.

Relationship between the serum level, polymorphism and gene expression of IL-33 in samples of recurrent miscarriage Iraqi women infected with toxoplasmosis

One of the many warm-blooded hosts that toxoplasmosis-causing intracellular protozoan parasite Toxoplasma gondii can infect is humans. Cytokines are crucial to stimulate an effective immune response against T. gondii. Interleukin-33 (IL-33) is a unique anti-inflammatory cytokine that suppresses the immune response. The levels of cytokine gene expression are regulated by genetics, and the genetic polymorphisms of these cytokines play a functional role in this process. Single nucleotide polymorphisms (SNPs) are prognostic indicators of illnesses. This study aimed to determine whether toxoplasmosis interacts with serum levels of IL-33 and its SNP in miscarriage women as well as whether serum levels and IL-33 gene expression are related in toxoplasmosis-positive miscarriage women. Two hundred blood samples from patients and controls were collected from AL-Alawiya Maternity Teaching Hospital and AL-Yarmouk Teaching Hospital in Baghdad, Iraq from 2021 to 2022 in order to evaluate the serum level of IL-33 using ELISA test. For the SNP of IL-33, the allelic high-resolution approach was utilized, and real time-PCR was performed to assess gene expression. The results showed that compared to healthy and pregnant women, recurrent miscarriage with toxoplasmosis and recurrent miscarriage women had lower IL-33 concentrations. Additionally, there were significant differences among healthy women, pregnant women, and women with repeated miscarriage who experienced toxoplasmosis. Furthermore, no differences between patients and controls were revealed by gene expression data. The results revealed that recurrent miscarriage, pregnancy, and healthy women all had a slightly higher amount of the IL-33 gene fold. Additionally, the SNP of IL-33 data demonstrated that there was no significant genetic relationship between patients and controls. Recurrent miscarriage women with toxoplasmosis have showed significant differences from pregnant women in the genotypes GG and AA as well as the alleles A and G. There were notable variations between recurrent miscarriage with and without toxoplasmosis in terms of the genotypes AA and AC. The genotypes GG, AA, and allele A in recurrent miscarriage women with toxoplasmosis and recurrent miscarriage women is a protective factor. Taking together, there was a statistically significant negative correlation between toxoplasmosis and IL-33 gene expression, which calls for more quantitative investigation in order to fully comprehend the interaction of mRNA and protein.

The Progress of Research on Genetic Factors of Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) is both mental and physical health problem affecting about 1-5% of women of childbearing age. The etiology of RPL is complex, involving chromosomal abnormalities, autoimmune diseases, metabolic disorders, and endometrial dysfunction. The causes of abortion are still unknown in more than 50% of these cases. With the development of science and technology, an increasing number of scholars focus on this field and find that genetic factors may play an essential role in unexplained RPL, such as embolism-related genes, immune factor-related genes, and chromosomal numeric, and structural variation. This review summarizes the genetic factors associated with RPL, including genetic mutations and genetic polymorphisms, chromosomal variants, and chromosomal polymorphisms. Many related genetic factors have been found to be demographically and geographically relevant, some of which can be used for risk prediction or screening for the etiology of RPL. However, it is difficult to predict and prevent RPL due to uncertain pathogenesis and highly variable clinical presentation. Therefore, the genetic factors of RPL still need plentiful research to obtain a more accurate understanding of its pathogenesis and to provide more detection means for the screening and prevention of RPL.

The Update Immune-Regulatory Role of Pro- and Anti-Inflammatory Cytokines in Recurrent Pregnancy Losses

Recurrent pregnancy losses (RPL) is a common reproductive disorder with various underlying etiologies. In recent years, rapid progress has been made in exploring the immunological mechanisms for RPL. A propensity toward Th2 over Th1 and regulatory T (Treg) over Th17 immune responses may be advantageous for reproductive success. In women with RPL and animals prone to abortion, an inordinate expression of cytokines associated with implantation and early embryo development is present in the endometrium or decidua secreted from immune and non-immune cells. Hence, an adverse cytokine milieu at the maternal-fetal interface assaults immunological tolerance, leading to fetal rejection. Similar to T cells, NK cells can be categorized based on the characteristics of cytokines they secrete. Decidual NK (dNK) cells of RPL patients exhibited an increased NK1/NK2 ratio (IFN-γ/IL-4 producing NK cell ratios), leading to pro-inflammatory cytokine milieu and increased NK cell cytotoxicity. Genetic polymorphism may be the underlying etiologies for Th1 and Th17 propensity since it alters cytokine production. In addition, various hormones participate in cytokine regulations, including progesterone and estrogen, controlling cytokine balance in favor of the Th2 type. Consequently, the intricate regulation of cytokines and hormones may prevent the RPL of immune etiologies. Local or systemic administration of cytokines or their antagonists might help maintain adequate cytokine milieu, favoring Th2 over Th1 response or Treg over Th17 immune response in women with RPL. Herein, we provided an updated comprehensive review regarding the immune-regulatory role of pro- and anti-inflammatory cytokines in RPL. Understanding the roles of cytokines involved in RPL might significantly advance the early diagnosis, monitoring, and treatment of RPL.

Plasma and amniotic fluid concentrations of nitric oxide: Effects on uterine artery and placental vasculature in women who underwent voluntary pregnancy termination and in women with missed and threatened abortion. A pilot study

OBJECTIVES

First trimester miscarriage is a multifactorial event. Various angiogenic factors have been proposed as possible early markers of non-viable pregnancies. The aim of the present study was to evaluate the systemic nitric oxide (NO) production in healthy early pregnancy and its possible role in first trimester miscarriage.

STUDY DESIGN

We prospectively enrolled women referred to our Unit for elective termination of pregnancy, threatened abortion or missed abortion. Blood samples were taken for testing circulating NO plasma levels. Subsequently, all patients underwent 2-D ultrasonographic analysis and Color Doppler imaging to assess the pulsatility index of the uterine arteries. 3-D ultrasonographic and power Doppler analysis allowed a volumetric and vascular reconstruction of the placenta. During dilatation and vacuum aspiration, amniotic fluid was collected.

RESULTS

Seventy-two patients were enrolled: 25 with elective termination of pregnancy (Group I); 17 with threatened abortion (Group II); 30 with missed abortion (Group III). Group II showed greater placental volume and lower uterine arteries PI than others. The plasma NO concentration resulted statistically higher in women with threatened abortion, while amniotic fluid NO concentration were higher in the viable pregnancies (Group I) than in the aborted fetuses (Group III). Plasma NO was inversely correlated with both mean arterial pressure and uterine artery PI and was positively correlated with amniotic fluid NO and CRL; amniotic fluid NO was positively correlated with placental Vascularization Index and Vascularization-Flow Index.

CONCLUSION

Amniotic NO concentration was higher in viable pregnancies and positively related to Doppler 3D indices of vascularization and blood flow within the placenta. Further studies are needed to elucidate its role in first trimester miscarriage.

Relationship between common interleukin 1-beta gene polymorphisms and the risk of gestational disorders: An updated meta-analysis

Background: To quantitatively estimate the relationship between IL-1β -511C>T, -31T>C, and +3954C>T polymorphisms and risk of gestational disorders. Methods: In this meta-analysis, eligible publications were searched in Web of Knowledge, MEDLINE, PubMed, Scopus, and Google Scholar databases (updated April 2020), using appropriate or relevant keywords. Case-control population-based reports were included if provided with genotypic frequencies of both studied groups. Statistical analyses were performed using the MetaGenyo web tool software, where a P value less than 0.05 indicated a significant association. For the assessment of between-study variations, heterogeneity analysis was applied with the I² statistics. Results: A total of thirteen studies were included. We observed a significant association between IL-1β-31T>C polymorphism and reduced risk of gestational disorders under codominant CT vs. CC [OR= 0.74, CI (0.59-0.92)], and dominant CT+TT vs. CC [OR= 0.74, CI (0.60-0.91)] contrasted genetic models. The stratified analysis considering the disease type showed that the 511C>T variant, under the recessive CC vs. CT+TT model, enhanced the risk of preterm birth by 1.29 fold. Conclusion: Our results failed to support an association between two IL-1β polymorphisms, 511C>T and +3954C>T, with the overall risk of gestational disorders. In contrast, the 31T>C variant reduced the incidence of such diseases. Further studies are encouraged to get more precise estimates of effect sizes.

Interleukin-1 beta is significantly upregulated in the decidua of spontaneous and recurrent miscarriage placentas

BACKGROUND

Pregnancy is an extraordinarily complex immunological process. For successful pregnancy maintenance the maternal immune system must adapt to and tolerate the semi-allogenic fetus at the fetomaternal interface of the placenta. This balance is regulated by cytokines with a predominant T helper 2 (Th-2) system and a suppressed inflammatory T helper 1 (Th-1) response. This study investigates the role of the Th-1 pro-inflammatory cytokine Interleukin-1 beta (IL-1β) and its role in early pregnancy loss.

PATIENTS AND METHODS

In order to identify differences in IL- β levels a TaqMan® Human Cytokine Network Array, with placental tissue obtained from patients with healthy pregnancies (n = 15) and recurrent miscarriage (n = 15), was carried out. Protein expression of IL-1β in the decidua of healthy pregnancies (n = 15), spontaneous (n = 18) and recurrent miscarriages (n = 15), was investigated by immunohistochemistry. The identification of IL-1β expressing cells in the decidua was done with double-immunofluorescence.

RESULTS

Gene expression analysis identified a nearly 54-times higher expression of IL-1β in placental tissue of patients suffering from recurrent abortion. Immunohistochemistry confirmed a significant upregulation of IL-1β in the decidua of recurrent miscarriage specimens (p = 0.01) as well as in the decidua of women with spontaneous abortion (p = 0.001). Double-immunofluorescence identified decidual stoma cells as IL-1β expressing cells.

CONCLUSION

Significant upregulation of IL-1β may be associated with an imbalanced immune system and a procoagulant state that could be responsible for early pregnancy loss. These results provide new evidence of the complex interplay of IL-1β at the fetomaternal interface and its crucial role in miscarriage processes.

Association of IL-10, IL-18, and IL-33 genetic polymorphisms with recurrent pregnancy loss risk in Iranian women

Recurrent pregnancy loss (RPL) is a heterogeneous disease with three or more consecutive abortions before 20 weeks of pregnancy. Recently, inflammatory factors such as interleukins (IL) have been found to be a significant factor in the RPL. The objective of this study was to investigate the association between RPL and IL-10 (rs1800896), IL-18 (rs1946518) and IL-33 (rs1929992) genes polymorphisms in Iranian women. The study participants consisted of 300 women with RPL and the control group comprised of 300 healthy women with successful delivery. Genomic DNA was extracted from peripheral blood, and genotyping was performed by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP). There were no significant differences in the frequencies of genotype and allele in IL-10 gene polymorphism (rs1800896) between patients and control group (p > .005). In contrast, there were significant differences in the frequencies of CC genotype in IL-18 gene polymorphism (rs1946518) between patients and the control groups (p = .004; OR =0.990; 95% CI: 0.320-8.855). Also, there were significant differences in the frequencies of GA genotype in IL-33 gene polymorphism (rs1929992) between patients and the control groups (p = .001; OR =0.955; 95% CI: 0.239-9.807). Present study showed that the rs1800896 polymorphism (IL-10) might not play role in RPL in the Iranian population; whereas rs1946518 (IL-18) and rs1929992 (IL-33) polymorphisms may be associated with the risk of RPL in the Iranian women.

Association of of IL-1 receptor antagonist (IL-1RN) and interleukin-1β genes (IL-1β) polymorphisms with recurrent pregnancy loss in Iranian Azeri women

Objective One of the most important problems in human reproduction is recurrent pregnancy loss (RPL). RPL is defined as three or more consecutive abortions in the first trimester of pregnancy. The association between the polymorphisms in the immunological factors and RPL was investigated. The aim of our study was to determine the association of interleukin receptor antagonist (IL-IRN) and interleukin-1β (IL-1β) polymorphisms with RPL in Iranian Azeri women. Materials and methods The study participants consisted of 100 women with RPL of Iranian Azeri origin. The control group comprised 100 age- and ethnically-matched healthy women of the same reproductive age. Genomic DNA was extracted from the whole blood and genotype determinations were performed using polymerase chain reaction (PCR) amplification followed by restriction fragment length polymorphism (RFLP) analysis. Results Our results showed no significant relationship between IL-1RN polymorphism and RPL. The homozygous state in -857 C/T variant was seen to be higher in RPL patients than in control subjects. Also frequency of wild type genotype was lower in RPL patients than in controls. However, this associations was not significant. Conclusion This study suggested that -511 C/T (rs16944) and -31 C/T (rs1143627) polymorphisms in IL-1β gene may not be involved in RPL in Iranian Azeri women. Also the promoter polymorphism of the IL-1RN gene may not play a role in the susceptibility to RPL.

The association of renin-angiotensinogen system genes polymorphisms and idiopathic recurrent pregnancy loss

The most common complication of pregnancy is idiopathic recurrent pregnancy loss (RPL). To identify the contribution of gene polymorphisms to this condition, we evaluated the association between RPL and the angiotensinogen (AGT), angiotensin receptor 1 (AGTR1) and Angiotensinogen converting enzyme (ACE). In this case-control study, the frequency of AGT (rs4762 and rs699), AGTR1 (rs5186) and ACE insertion/deletion (rs4340) polymorphisms in 202 idiopathic RPL women was compared with 210 women with no history of abortion, using tetra-primer ARMS-PCR. Polymorphisms were analysed by logistic regression analysis according to inheritance models. The CT genotype of AGT rs4762, the CC genotype of AGT rs699 and the AC genotype of AGTR1 rs5186 in a co-dominant inheritance model were associated with idiopathic RPL (OR = 1.63, 95% CI = 1.07-2.49 of CT versus CC; OR = 5.97, 95% CI = 1.28-27.82 of CC versus TT; and OR = 1.99, 95% CI = 1.22-3.07 of AC versus AA). The allele frequency of AGT rs699 and AGTR1 rs5186 polymorphisms, but not AGT rs4762 and ACE rs4340 polymorphisms were significantly different between women with RPL patients and controls (p = 0.020, p = 0.003, p = 0.105 and p = 0.065, respectively). These results show that there is a significant relationship between AGT (rs699) and AGTR1 (rs5186) polymorphisms and idiopathic RPL in the Iranian population.

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.

Effects of coagulation factor XIII (Val34Leu) polymorphism on recurrent pregnancy loss in Iranian Azeri women

Background:

Recurrent pregnancy loss (RPL) is a heterogeneous condition consisting of two or more consecutive abortions occurring before 20 weeks of gestation. One of the clotting factor genes encodes factor XIII (

Methods:

A prospective case-control study was performed on a cohort of 310 RPL patients and 290 healthy controls. DNA was extracted from the whole blood and fragments of the Val34Leu polymorphism were amplified by polymerase chain reaction (PCR), followed by DNA sequencing. Genotyping was performed using the Sequenom MassArray system.

Results:

The genotype frequencies of

Conclusions:

No significant association was observed between the Val34Leu polymorphism and RPL among Iranian Azeri women.

Association between Genetic Polymorphisms in Interleukin Genes and Recurrent Pregnancy Loss - A Systematic Review and Meta-Analysis

Interleukins are a group of immunomodulatory proteins that mediate a variety of immune reactions in the human body. To investigate the association between interleukin gene polymorphisms and recurrent pregnancy loss (RPL), we reviewed 21 studies from MEDLINE, EMBASE, OVID SP and PubMed to evaluate RPL-related interleukin gene polymorphisms. Meta-analysis was performed on 12 of the polymorphisms, and a review included the others. Our integrated results indicated that IL-1β (-511C/T) (P = 0.02, 95% CI 0.77[0.62,0.96]), IL-6 (-634C/G) (P<0.001, 95% CI 2.91[2.01,4.22]), IL-10 (-1082G/A, -819T/C) (P = 0.01, 95% CI 0.80[0.67,0.96]; P<0.01, 95% CI 0.66[0.49,0.89]), and IL-18 (-137G/C, -105G/A) (P<0.01, 95% CI 1.69[1.24,2.31]; P = <0.01, 95% CI 1.41[1.17,1.70]) consistently associated with RPL after meta-analysis. IL-17A rs2275913 and IL-17F rs763780, IL-21 rs2055979 and rs13143866, IL-1β (-31C/T), IL-6 (-2954G/C), and IL-10 (-536A/G) were reported only once as having a significant association with RPL. The potential mechanism underlying miscarriage and these polymorphisms and future research directions are also discussed.

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.

Genetic variant in interleukin-18 is associated with idiopathic recurrent miscarriage in Chinese Han population

Levels of IL-18 were significantly lower in women with recurrent miscarriage (RM) than those without idiopathic RM. IL-18 promoter single nucleotide polymorphisms were previously identified to have an impact on IL18 gene transcription activity and influence the level of IL-18 protein production. The aim of this study was to evaluate whether IL-18 gene polymorphisms are risk factors for idiopathic RM in Chinese Han population. Study subjects comprised of 484 idiopathic RM patients and 468 controls. Three polymorphisms (rs360717, rs187238, rs1946518) in IL-18 gene and serum IL-18 concentrations were assessed. rs187238 variant exhibits significant association with RM in additive and recessive genetic model (additive model p = 1.05 × 10⁻⁴, dominant model p = 0.025, recessive model p = 2.43 × 10⁻⁵). In contrast, rs360717 and rs1946518 are not significantly associated with RM. Serum IL-18 levels are significantly lower in RM cases than in control (111.98 ± 93.13 versus 148.74 ± 130.51 pg/mL, p = 7.42 × 10⁻⁷). There are lower levels of serum IL-18 in rs187238 homozygous mutant (CC) than homozygous wild-type (GG) in this study population, including cases and control groups (98.31 ± 86.46 versus 131.87 ± 115.02 pg/mL, p = 0.015). These results suggest that reduced IL-18 levels and rs187238 variant may contribute to pathogenesis of idiopathic RM in Chinese Han population.

Spontaneous abortion and functional polymorphism (Val16Ala) in the manganese SOD gene

Spontaneous abortion is the most common complication of early pregnancy. Genetic factors have been hypothesised to play a role in spontaneous abortion. Since it is possible that the balance of oxidants and antioxidants can be affected by different genetic variants, gene polymorphisms have been proposed as a susceptibility factor that increases the chance of miscarriage. Manganese superoxide dismutase is an important antioxidant enzyme encoded by manganese superoxide dismutase (MnSOD) gene. The aim of this experiment was to assess whether Val16Ala polymorphism of MnSOD gene is associated with miscarriage in northern Iran. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used for genotyping. Statistical analyses were conducted using the χ(2)-test. The genetic distributions did not differ significantly between cases and controls, however slightly more Val/Val genotypes were found among the patients compared with control subjects (p = 0.059). No correlation was observed between susceptibility to abortion and MnSOD Val16Ala polymorphism. Larger population-based studies are needed for clarifying the relationship between abortion and MnSOD genotypes.

Genetic association studies of endothelial nitric oxide synthase gene polymorphisms in women with unexplained recurrent pregnancy loss: a systematic and meta-analysis

Recurrent pregnancy loss (RPL) is a multifactorial disorder, both genetic and environmental factors contribute to the development of RPL. Recently, the association between endothelial nitric oxide synthase (eNOS) gene polymorphisms and unexplained recurrent pregnancy loss (URPL) has been reported, and the results were inconsistent. Hence, we performed the meta-analysis to drive a more precise estimation of association between eNOS polymorphisms and URPL. Odds ratio (OR) and its 95% confidence interval were calculated under co-dominant (AA vs. BB, TT vs. GG) and additive (A vs. B, T vs. G) genetic models. Studies of eNOS intron 4 VNTR and Glu298Asp were separated by ethnicities. 13 studies included 1,769 URPL cases and 1,376 healthy controls on eNOS intron 4 VNTR polymorphism, and 11 studies were involved in Glu298Asp polymorphism with 1,498 URPL cases and 1,123 healthy controls. The integrated results showed that eNOS Glu298Asp polymorphism was associated with URPL [ORs were 1.91 (1.42-2.56), P < 0.001; 1.67 (1.36-2.04), P < 0.001, respectively]. When analyses were separated by ethnic subgroups, the association between eNOS Glu298Asp polymorphism and URPL was only observed in East Asians [OR = 1.88 (1.52-2.33), P < 0.001 under additive model], and there was no association between eNOS intron 4 VNTR polymorphism and URPL in Caucasians and East Asians. The results indicated a significant association between eNOS Glu298Asp polymorphism and URPL in East Asians. No association was observed between eNOS intron 4 VNTR polymorphism and URPL in Caucasians and East Asians.

Single-nucleotide polymorphisms in genes involved in placental function and unexplained stillbirth

OBJECTIVE

The purpose of this study was to evaluate the association between unexplained stillbirth (SB) and single-nucleotide polymorphisms (SNPs) in genes involved in placental function using a well-characterized cohort.

STUDY DESIGN

Placentas were obtained from 50 unexplained SB and 46 live birth controls. Classification of stillbirth was by Wigglesworth criteria. SBs were stratified by weight: appropriate (AGA-SB) and small for gestational age (SGA-SB, less than the 10th percentile) and gestational age: before 32 and after 32 weeks. Placental DNA was extracted and various SNPs in the endothelial nitric oxide synthase (eNOS), Klotho, hypoxic inducible factor-1α, and and tumor necrosis factor-α genes were evaluated.

RESULTS

None of the SNPs were associated with SB overall. Significantly different genotype distribution emerged for eNOS-SNP rs1800783 when comparing AGA-SB with SGA-SB and control (P = .004). Its allele-A was more frequent in AGA-SB compared with both controls (P = .03) and SGA-SB (P = .001). No differences were seen accordingly to gestational age.

CONCLUSION

Unexplained stillbirth in the setting of adequate growth is associated with carrier of allele A of rs1800783 eNOS gene in the placenta.

Genetics of recurrent miscarriage: challenges, current knowledge, future directions

Recurrent miscarriage (RM) occurs in 1-3% of couples aiming at childbirth. Due to multifactorial etiology the clinical diagnosis of RM varies. The design of genetic/"omics" studies to identify genes and biological mechanisms involved in pathogenesis of RM has challenges as there are several options in defining the study subjects (female patient and/or couple with miscarriages, fetus/placenta) and controls. An ideal study would attempt a trio-design focusing on both partners as well as pregnancies of the couple. Application of genetic association studies focusing on pre-selected candidate genes with potential pathological effect in RM show limitations. Polymorphisms in ∼100 genes have been investigated and association with RM is often inconclusive or negative. Also, implication of prognostic molecular diagnostic tests in clinical practice exhibits uncertainties. Future directions in investigating biomolecular risk factors for RM rely on integrating alternative approaches (SNPs, copy number variations, gene/protein expression, epigenetic regulation) in studies of single genes as well as whole-genome analysis. This would be enhanced by collaborative network between research centers and RM clinics.

Interleukin-1 gene cluster variants and recurrent pregnancy loss among North Indian women: retrospective study and meta-analysis

The aim of this study was to determine whether or not interleukin-1 alpha (IL-1a), interleukin-1 beta (IL-1b) and IL-1 receptor antagonist (IL-1RA) polymorphisms are associated with risk of unexplained recurrent pregnancy loss (RPL) among North Indian women. This retrospective case–control study examine 200 well-characterized RPL cases for IL-1 gene cluster variants, determined by restriction fragment length polymorphism-PCR. The observed allele, genotype and haplotype distributions were compared with those obtained from 300 ethnically matched negative controls. Invariant distribution of IL-1 gene cluster single-nucleotide polymorphisms was observed among RPL cases and controls. Meta-analysis of IL-1b _511, +3953 and IL-1RN 86-bp variable number tandem repeat from the reported literature and this study did not reveal any significant association with the risk of RPL. In conclusion, no significant difference between RPL and control groups was observed at the allele, genotype or haplotype levels when tested for association using the dominant, recessive and additive models of inheritance for IL-1 gene cluster variants. As far as is known, this is the first report from India pertaining to IL-1 gene cluster variants’ association with the risk of RPL from North India.

Association of IL-1β and IL-6 gene polymorphisms with recurrent spontaneous abortion in a Chinese Han population

As certain cytokines may play a role in unexplained recurrent spontaneous abortion (RSA) and also some cytokine gene polymorphisms may affect the level of cytokine production, the aim of this study was to investigate the relationship between Chinese RSA and polymorphisms of the genes coding for interleukin (IL)-1β (-31C/T, -511C/T, +3954C/T) and IL-6 (-634C/G). Women (n = 162) with at least three consecutive spontaneous abortions and 156 ethnically matched healthy women with at least one successful pregnancy were included. Genotypes were determined using restriction fragment length polymorphism analysis of polymerase chain reaction products. No significant differences were found in the IL-1β-31T, -511T and +3954T distributions between the RSA group and the control group. On the other hand, the frequencies of the IL-6-634GG genotype and -634G allele were significantly decreased in the RSA group versus the control group (genotype: P = 0.0003; allele: P = 0.002), suggesting the IL-6-634C/G polymorphism might be a possible genetic protective factor for RSA.

Vascular endothelial growth factor gene polymorphisms in Korean patients with premature ovarian failure

OBJECTIVE

To study the association of vascular endothelial growth factor (VEGF) polymorphisms (-2578C>A, -1154G>A, -634G>C, and 936C>T) with premature ovarian failure (POF) in Korean patients.

STUDY DESIGN

Prospective case-control study. One hundred and thirty five patients with POF and confirmed serum follicle-stimulating hormone levels of >40IU/L before the age of 40 years and 120 healthy controls with at least one live birth, regular menstrual cycles, and karyotype 46, XX.

RESULTS

POF patients exhibited significantly different frequencies of the VEGF -1154GA genotype (odds ratio [OR], 2.002; 95% confidence interval [CI], 1.116-3.592; P=0.019), and -2578CA+AA/-1154GA+AA combination genotype (OR, 1.805; 95% CI, 1.013-3.217; P=0.044) compared to the control group. The frequency of the -2578A/-1154A haplotype (OR, 1.647; 95% CI, 1.017-2.677; P=0.041) was significantly higher in the POF group than in the control group.

CONCLUSION

The VEGF -1154G>A mutation, -2578CA+AA/-1154GA+AA combination genotype, and -2578A/-1154A haplotype are significantly associated with POF in Korean women.

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.

Haplotype-based association of ACE I/D, AT1R 1166A>C, and AGT M235T polymorphisms in renin-angiotensin-aldosterone system genes in Korean women with idiopathic recurrent spontaneous abortions

OBJECTIVES

The objective of this study was to determine whether or not the angiotensin-converting enzyme insertion/deletion (ACE I/D), angiotensin II type 1 receptor (AT1R), and angiotensinogen (AGT) gene polymorphisms are associated with idiopathic recurrent spontaneous abortions (RSAs) in Korean women.

STUDY DESIGN

A total of 251 patients with unexplained consecutive pregnancy losses, and 126 healthy controls with at least one live birth and no history of pregnancy loss.

RESULT

The odds ratios (ORs) of the ACE ID (OR=2.423; 95% confidence interval (CI)=1.417-4.142; p=0.001) and the ACE II (OR=2.050; 95% CI=1.143-3.675; p=0.018) for the ACE DD genotype were significantly different between patients with idiopathic RSA and controls; however, there were no significant differences between patients and controls with respect to the AT1R 1166A>C and AGT M235T polymorphisms. In a haplotype-based analysis of I-A (p=0.010), D-A (p=0.004), I-A-T (p=0.033), D-A-T (p=0.0005), and D-C-T (p=0.013) polymorphism pairs with synergistic effects derived by the MDR method in patients and in controls showed significant results.

CONCLUSION

This study suggests that ACE, AT1R and AGT polymorphisms and haplotypes are a genetic determinant for the risk of idiopathic RSA in Korean women.

Genetic analysis of eNOS gene polymorphisms in association with recurrent miscarriage among North Indian women

This study investigated the association of common polymorphisms of the endothelial nitric oxide synthase (eNOS) gene with recurrent miscarriage (RM) among North Indian women. A total of 200 patients with unexplained recurrent miscarriages and 300 controls were genotyped for six polymorphic regions of eNOS by PCR, re-sequencing and RFLP. The GG genotype of 12862A>G, the G allele of Glu298Asp and the aa genotype of intron 4VNTR increased the risk of RM by ∼1.8-fold, ∼3.5-fold and ∼2-fold, respectively (odds ratio (OR) 1.84, 95% confidence intervals (CI) 1.19-2.86, P=0.0066; OR 3.58, 95% CI 2.12-6.03, P<0.0001; and OR 2.23, 95% CI 1.04-4.77, P=0.0493). Two haplotypes were found to have a significant protective effect against RM (OR 0.63, 95% CI 0.48-0.82, P=0.0009; and OR 0.4, 95% CI 0.19-0.81, P=0.0149) and another was found to increase the risk of RM by ∼2-fold (OR 2.12, 95% CI 1.16-3.89 P=0.0195). In conclusion three common polymorphisms of eNOS gene, 12862A>G, Glu298Asp and intron 4VNTR increase the risk of RM in North Indian women. Risk of RM may also be modified by the presence of particular haplotypes.

Cytokine gene polymorphisms in recurrent spontaneous abortions: a comprehensive review

PROBLEM

Cytokine gene polymorphism studies in women with recurrent spontaneous abortion (RSA) are reviewed to provide comprehensive understanding and a direction for the future investigation.

METHOD OF STUDY

A search of PubMed was made to identify the published data between 2001 and 2007 regarding RSA and cytokine gene polymorphisms.

RESULTS

Either allele and/or genotype frequencies of the following polymorphisms were reported to be significantly different between women with RSA and controls: IFN-gamma +874A-->T, TA (P = 0.01), AA (P = 0.04); IL-6, -634C-->G CG/GG (P = 0.026); IL-10, -592C-->A CC (P = 0.016); IL-1B -511C (P = 0.035), -31T (P = 0.029); IL-1RA, IL1RN*2 (P = 0.002), and IL1RN*3 (P = 0.002). None of these studies was repeatedly reported by others to be significantly different. Among these, four cytokine polymorphisms (IFN-gamma, +874A-->T; IL-1B -511C; IL-1RA, IL1RN*2, IL1RN*3) were refuted by others and rest of them were studied once.

CONCLUSION

Multiple cytokine polymorphisms were reported to be associated with RSA. However, a majority of studies were not confirmed by other investigators or refuted by others. Inconsistent study results might be related to: (i) the production of these cytokines is partly under genetic controls and other factors affect cytokine levels; (ii) ethnic background, environmental factors, and selection criteria for study populations are different and (iii) the possibilities exist that multiple cytokine gene polymorphisms or other genes in linkage disequilibrium may play a role in RSA.

Cytokine polymorphisms in women with recurrent pregnancy loss: meta-analysis

BACKGROUND

Inflammatory cytokine cascades have been implicated in the pathogenesis of recurrent pregnancy loss (RPL). Polymorphisms in cytokine genes may affect the risk of RPL, but genetic association studies are often limited by small sample sizes. Meta-analysis of all available studies can increase the precision of these estimates.

AIMS

To assess and synthesise the available data from association studies of inflammatory cytokine polymorphisms with RPL.

METHODS

Systematic review and random effects meta-analysis of genetic association studies.

RESULTS

Sixteen reports of genetic association studies of cytokine polymorphisms with RPL were identified. Meta-analyses did not identify any significant associations with tumour necrosis factor (-308A, or -238A), interferon-gamma (+874T), interleukin (IL)-1beta (-511T), IL-6 (-174G), or IL-10 (-1082A, or -819T, or -592A). Significant associations were found with IL-1B (-31T) (two studies: pooled odds ratio (OR) 2.12 (95% confidence interval (CI) 1.04 to 4.33)) and IL-6 (-634G) (one study: OR 0.22 (95% CI 0.09 to 0.57)).

CONCLUSIONS

The available data are not consistent with more than modest associations between these candidate cytokine polymorphisms and RPL. Data from future association studies may be added to the meta-analyses to obtain more precise estimates of effect sizes.

Evidence for association of the G1733A polymorphism of the androgen receptor gene with recurrent spontaneous abortions

OBJECTIVE

To determine whether the G1733A polymorphism of the androgen receptor gene is associated with an increased risk for recurrent spontaneous abortion (RSA).

DESIGN

Case-control study.

SETTING

Division of Genetics and Biotechnology, Department of Biology, University of Athens.

PATIENT(S)

A total of 131 women with at least three unexplained spontaneous abortions before 20 weeks' gestation, with the same partner, composed the study group.

INTERVENTION(S)

Subjects were genotyped by the polymerase chain reaction-restriction fragment length polymorphism method.

MAIN OUTCOME MEASURE(S)

G1733A polymorphism genotypes and allele frequencies.

RESULT(S)

The observed frequencies of GG, GA, and AA genotypes of the G1733A polymorphism were 0.57, 0.27, and 0.16, respectively, for the patient group and 0.76, 0.15, and 0.09, respectively, for the control group. Allele frequencies were 0.70 and 0.84, respectively, for the patient and control groups for the G allele (wild type) and 0.30 and 0.16, respectively, for the patient and control groups for the A allele (mutant). Statistical analysis of these results indicated significant differences between the two groups.

CONCLUSION(S)

These results indicated for the first time that the androgen receptor G1733A polymorphism is strongly associated with increased risk for RSA.

Endothelial nitric oxide synthase gene polymorphisms in recurrent spontaneous abortions

OBJECTIVE

The risk of miscarriage is enhanced by a variety of genetic and environmental factors. Previous studies indicated an association between endothelial nitric oxide synthase (eNOS) activity, and implantation and maintenance of pregnancy, but it is rather controversial whether polymorphisms of the gene encoding for eNOS are associated with recurrent spontaneous abortions (RSA). The aim of our study was to determine whether the 27 bp intron 4 repeat polymorphism (4VNTR) and a Glu298Asp missense mutation encoded by exon 7 of the eNOS gene are associated with an increased risk for recurrent spontaneous abortions (RSA), in the Greek population.

METHODS

A total of 126 women who had at least three unexplained spontaneous abortions before 20 weeks of gestation, with the same partner, were included in the study group. The control group consistent of 130 women with at least two live childbirths and without history of abortions. All patients and controls were investigated for the two polymorphisms. To genotype the cohorts we used the PCR-RFLPs method.

RESULTS

The observed frequencies of bb, ba, aa genotypes of the VNTR, in intron 4, polymorphism were 0.75, 0.24, 0.01, respectively, for the patient group and 0.73, 0.24, 0.03, respectively, for the control group. The observed frequencies of GG, GT, TT of the Glu298Asp polymorphism were 0.42, 0.45, 0.13, respectively, for the patient group and 0.47, 0.45, 0.08, respectively, for the control group. Statistical analysis of the results indicates no significant difference between the two groups, for both the two studied polymorphisms.

CONCLUSION

Our results do not show any influence of the two polymorphisms, VNTR in intron 4 and Glu298Asp of the eNOS gene, on early pregnancy.

Dysplasia: a review

Bronchopulmonary dysplasia (BPD) is a common perinatal complication of very low birth weight preterm infants with a significant risk of long-term disability and morbidity. While clinical conditions such as prematurity and mechanical ventilation are its major risk factors, studies suggest that there is an individual susceptibility to BPD. This comprehensive review summarizes data collected about the implication of genetic polymorphisms in BPD and in its risk factors. Some studies have directly related the risk of BPD to genotype. Indeed, carrier states of genetic variants of cytokines (IFNgamma T+874A), adhesion molecules (L-selectin-Pro213Ser), elements of renin-angiotensin system (ACE-I/D), antioxidant enzymes (GST-P1 Val105Ile), and surfactant proteins (SPA1, SPB intron 4) has been identified as risk factors to BPD. Other studies investigated the role of genotype in BPD risk factors. Premature birth has been linked to carrier states of genetic variants with an impact on immune status (such as IL-6 G(-174)C, MBL2 54G/A, VEGF G+405C, HSP72 A+1267G genes) and matrix metalloproteases. Fetal inflammatory response syndrome, a major determinant of BPD is also affected by genotype (including LTalpha A+250G). Disturbed intrauterine lung development and vascularization may also contribute to BPD; these processes may be impaired in the presence of some rare genetic mutations. Furthermore, there is also a genetic component in the susceptibility to other perinatal adaptational disturbances such as respiratory distress syndrome that are associated with an increased need for mechanical ventilation, and, hence, with lung damage. The genetic variants presented in this article may help to identify infants at risk for BPD.

Association of interleukin-1beta and interleukin-1 receptor antagonist polymorphisms with bacterial vaginosis in non-pregnant Italian women

Bacterial vaginosis (BV) is the most prevalent alteration of vaginal microflora worldwide. BV is a polymicrobial disorder, and its etiology is elusive. Factors predisposing to this recurrent condition are not fully characterized. We aimed to investigate whether interleukin-1beta (IL-1beta) and IL-1 receptor antagonist (IL-1ra) polymorphisms are associated with BV in non-pregnant white Italian women. Genomic DNA was obtained from 164 BV positive, and 406 control women. Two diallelic polymorphisms in the IL-1beta gene (IL-1B) representing C/T base transitions at - 511 and + 3954 positions and a variable number tandem repeats (VNTR) in intron 2 of the IL-1ra gene (IL-1RN) were assessed. We demonstrated that women who were homozygous for - 511 CC or + 3954 TT of the IL-1B gene were at increased risk for BV with an odds ratio (OR) = 1.5 [95% confidence interval (CI) = 1.03-2.14, P = 0.032], and OR = 2.8 (95% CI = 1.37-5.88, P = 0.004), respectively. The haplotype - 511/ + 3954 T-C was protective for BV, with an OR = 0.7 (95% CI = 0.49-0.90, P = 0.009). The IL-1RN VNTR genotype was not associated with BV, although the rare allele 3 showed a trend towards protection (P = 0.049). These data show that host genetic variants at the IL-1beta locus predispose to BV among Caucasian non-pregnant women. Further studies will determine whether these genetic polymorphisms modulate the risk for BV recurrence, and/or BV associated severe adverse outcomes as preterm birth and human immunodeficiency virus transmission.

Inflammation and miscarriage

Most relevant studies in animals and humans indicate that some degree of systemic or uterine inflammation is necessary both for normal implantation and pregnancy. However, if inflammation becomes too excessive it might cause pregnancy complications such as fetal resorption/miscarriage. The main regulator of the correct level of inflammation at the feto-maternal interface seems to be the uterine CD16(-) CD56(bright) natural killer (NK) cells. Trophoblast debris, apoptotic cells and progesterone probably stimulate/regulate the production of inflammatory cytokines from these cells. Miscarriage of karyotypically normal embryos may occur when the level of inflammation at the feto-maternal interface falls outside the optimal range. This may be caused by an insufficient influx of CD56(bright) NK cells into the decidua, too little soluble histocompatibility leukocyte antigen (HLA)-G secretion from the trophoblast, hypersecretion of inflammatory cytokines due to the presence of high-production polymorphisms, presence of maternal HLA-DR alleles associated with high tumor necrosis factor (TNF)-alpha production, or maternal mannose-binding lectin deficiency.

Interleukin-18 gene promoter polymorphisms and recurrent spontaneous abortion

BACKGROUND

IL-18 is a multifunctional cytokine capable of inducing either Th1 or Th2 polarization depending on the immunologic milieu. IL-18 is detected at the materno-fetal interface very soon in early pregnancy. Two polymorphisms in the promoter region of the IL-18 gene at positions of -607 and -137 appear to have functional impacts.

OBJECTIVE

This study attempts to evaluate the frequency of these two polymorphisms in the IL-18 gene promoter in patients with recurrent spontaneous abortion (RSA) and normal pregnant women.

SUBJECTS AND METHODS

One hundred and two RSA patients and 103 healthy pregnant women were enrolled in this study. Single nucleotide polymorphisms of the IL-18 gene at positions -607 (C/A) and -137 (G/C) were analyzed by the sequence-specific PCR method.

RESULTS

There was no significant association between the allele, genotype, and haplotype frequencies of the two single nucleotide polymorphisms (SNPs) in the IL-18 gene promoter and RSA.

CONCLUSION

The results of this study showed that IL-18 gene promoter polymorphisms at positions -607 and -137 did not confer susceptibility to RSA in southern Iranian patients.

Polymorphisms of the endothelial nitric oxide synthase gene in breast cancer

Nitric oxide (NO) is known to be critically involved in breast carcinogenesis. Genetic polymorphisms of the gene encoding for endothelial nitric oxide synthase (Nos3), the enzyme catalyzing the production of the NO, are known to predispose to malignant disease. Whether these polymorphisms also influence breast cancer risk is unknown. In the present case-control study, we ascertained 2 polymorphisms of the Nos3 gene cluster (Nos3 exon 7 Glu298Asp and a 27-base pair repeat in intron 4 of Nos3) in 269 Caucasian patients with breast cancer and 244 healthy controls using pyrosequencing and PCR, respectively. Presence of the exon 7 Nos3 polymorphism predisposed women to breast cancer (p=0.03, Odds ratio [95% Confidence Intervals]=1.9 [1.1-3.6]), but was not associated with any clinico-pathological parameters. No significant associations were ascertained with respect to the intron 4 Nos3 polymorphism. In our series, presence of the mutant exon7 Nos3 polymorphism was associated with an increased risk for breast cancer in Caucasian women.

Future directions of failed implantation and recurrent miscarriage research

Recurrent implantation failure is today the major reason for women completing several IVF/intracytoplasmic sperm injection attempts without having achieved a child, and is probably also the explanation for many cases of unexplained infertility. Most causes of recurrent miscarriage are still poorly elucidated, but from a theoretical point of view recurrent implantation failure and recurrent miscarriage are suggested to have partly overlapping causes. Recent research has indeed documented that both syndromes can be caused by the same embryonic chromosomal abnormalities and the same maternal endocrine, thrombophilic and immunological disturbances. Consequently, many treatments attempting to normalize these abnormalities have been tested or are currently used in women with both recurrent implantation failure and recurrent miscarriage. However, no treatment for the two syndromes is at the moment sufficiently documented to justify its routine use. In this review, an overview is given regarding present knowledge about causes that may be common for recurrent implantation failure and recurrent miscarriage, and suggestions are put forward for future research that may significantly improve understanding and treatment options for the syndromes.

Pyrosequencing: sequence typing at the speed of light

Nucleotide sequencing is an established method for gaining information relating to partial gene, whole gene, or whole genome sequence. Here we describe some of the background leading to the advent of modern nucleotide sequencing and how it has led to the development of Pyrosequencing, a relatively new method for real-time nucleotide sequencing. In particular, we describe how this method can be used for typing bacterial pathogens.

The influence of Nos3 polymorphisms on age at menarche and natural menopause

OBJECTIVE

Deficiency of the gene encoding endothelial nitric oxide synthase, i.e. Nos3, has been reported to be associated with late menarche, reduced ovulation rates, fewer deliveries, and earlier onset of menopause in a mouse model.

METHODS

We assessed the Glu298Asp and the T-786C polymorphisms of Nos3 in 87 consecutive healthy postmenopausal women by pyro- and capillary-sequencing, respectively. Results were correlated with age at menarche and natural menopause, number of miscarriages and live births, as well as body mass index (BMI) and smoking habits.

RESULTS

Allelic frequencies of the Glu298Asp polymorphism of Nos3 were 121 (69.5%) and 53 (30.5%) for the wild-type G allele and the mutant T allele, respectively. Forty-one women (47.1%) were homozygote wild-type (G/G), 39 (44.9%) were heterozygote (G/T), and 7 (8.0%) were homozygote mutant (T/T). Allelic frequencies of the T-786C polymorphism of Nos3 were 105 (60.6%) and 69 (39.4%) for the wild-type T allele and the mutant C allele, respectively. Thirty-three women (38.0%) were homozygote wild-type (T/T), 39 (45.1%) were heterozygote (T/C), and 15 (16.9%) were homozygote mutant (C/C). Presence of at least one mutant allele of the Glu298Asp or the T-786C polymorphisms of Nos3 were not associated with age at menarche, natural menopause, and number of miscarriages and deliveries. BMI above 27 kg/m2 and smoking were associated with earlier onset of natural menopause (47.8 years versus 50.2 years (P = 0.01) and 46.8 years versus 49.8 years (p = 0.02)).

CONCLUSIONS

Our data show that smoking and increased BMI, but not Glu298Asp or the T-786C polymorphisms of Nos3, are associated with an early onset of natural menopause.

Vasoconstrictively acting AT1R A1166C and NOS3 4/5 polymorphisms in recurrent spontaneous abortions (RSA)

PROBLEM

Inadequate uteroplacental perfusion is one of the main reasons for recurrent spontaneous abortions (RSA). Coagulation, fibrinolysis, and vasoconstriction affect tissue perfusion. These systems are regulated by different gene products. Polymorphisms can modulate the expression levels of the respective genes and can thereby affect perfusion. Vasoconstriction is influenced by the expression of endothelial nitric oxide synthase (eNOS) and of the angiotensinogen II type 1 receptor (AT1R).

METHOD

The aim of our study was to investigate, whether two polymorphisms in the AT1R and NOS3 genes shown to result in maternal vasoconstriction are associated with an increased risk for RSA.

RESULTS

Our data indicate that the vasoconstrictively acting genotypes AT1R C/C and NOS3 4/4 are of similar prevalence in RSA patients and in controls.

CONCLUSION

Results do not show any influence of the polymorphisms studied on early pregnancy development. This is in concordance with the concept of an independent regulation of placental perfusion.

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

PROBLEM

It is controversial whether polymorphisms of methylenetetrahydrofolate reductase (MTHFR) and the endothelial nitric oxide synthase (eNOS) are associated with recurrent pregnancy loss.

METHOD OF STUDY

We studied the frequency of the C677T polymorphism of MTHFR and a eNOS gene polymorphism, as well as the plasma levels of homocysteine and NO, in 85 cases with a history of two or more unexplained embryonal losses, 40 patients suffering fetal loss and 76 controls.

RESULTS

The frequency of the MTHFR gene T allele, which has been reported to be associated with miscarriages, in patients suffering fetal loss was rather significantly lower than in controls whereas there was no difference in the frequency of the eNOS gene A allele. There were no differences in the plasma homocysteine levels among the three groups. However, the NO concentrations in the embryonal loss and fetal loss groups were significantly higher than that in controls.

CONCLUSION

We conclude that the NO concentration but not the polymorphism of MTHFR and eNOS gene and hyperhomocysteinemia are associated with recurrent pregnancy loss in Japanese.