Genetic Polymorphisms and Recurrent Spontaneous Abortions: An Overview of Current Knowledge

The Association between Histidine-Rich Glycoprotein rs10770 Genotype and Recurrent Miscarriage in Iranian Women

Purpose

Recurrent miscarriage (RM) is a significant reproductive concern affecting numerous women globally. Genetic factors are believed to play a crucial role in RM, making the histidine-rich glycoprotein (HRG) gene, a topic of interest due to its potential involvement in angiogenesis. This study is aimed at investigating the association between the HRG rs10770 genotype and RM.

Method

Blood samples were collected from a total of 200 women at the beginning of the study. Subsequently, a comparative analysis was conducted between the blood samples of 100 women with a history of RM (case group) and the blood samples of another 100 healthy women (control group). HRG rs10770 genotyping was performed through polymerase chain reaction restriction-fragment length polymorphism (PCR-RFLP), followed by statistical analysis to evaluate the relationship between HRG rs10770 genotype and RM.

Results

The results indicated a significant statistical difference between the C/C genotype (OR = 3.32, CI: 1.22-9.04, p = 0.01) and the C/T genotype (OR = 1.24, CI: 0.67-2.30, p = 0.47) in both the case and control groups. Additionally, a significant correlation was observed in the C allelic frequency among RM participants compared to the control group (OR = 1.65, CI: 1.06-2.58, p = 0.02).

Conclusion

The study highlights the importance of HRG rs10770 in understanding RM, shedding light on its implications for reproductive health. Furthermore, it became evident that women carrying the homozygous C/C genotype exhibited increased susceptibility to the risk of RM.

Role of tumor necrosis factor-alpha -238 G>A promoter region polymorphism on recurrent miscarriage: An association study and meta-analysis

BACKGROUND

Recurrent miscarriage (RM) is defined as the loss of two or more consecutive pregnancies. A functional SNP, -238G>A in the promoter region of TNF-α, affects the gene transcription activity with implications on human pregnancy. Previous limited studies, linking the TNF-α -238 G>A to the risk of recurrent miscarriage have been inconclusive.

MATERIAL AND METHOD

The PCR-RLFP technique was used to evaluate this polymorphism in 199 RM cases and 215 control women from Amritsar, Punjab. For a meta-analysis, a total of 13 eligible studies (including the present study) comprising 2947 cases and 2933 controls were included. To evaluate the association among different genetic models, odds ratio with a 95% confidence interval (CI) and chi-square were used.

RESULTS

Genotype and allelic frequency did not differ significantly between both groups (p = .07 and p = .24, respectively). In the present meta-analysis, a significant association was found with the recessive model (OR-1.78 CI:1.24-2.55, p = .002).

CONCLUSION

Although, TNF-α -238 G>A polymorphism did not provide any risk in the case-control study but provided risk towards the development of RM with the recessive genetic model in the pooled analysis.

Role of the vaginal microbiome in miscarriage: exploring the relationship

Miscarriage is a devastating pregnancy loss that affects many women worldwide. It is characterized as a spontaneous miscarriage that occurs before 20 weeks of gestation which affects more than 25% of pregnancies. While the causes of miscarriage are complex and multifactorial, recent research has suggested a potential role of the vaginal microbiota. The vaginal microbiome is a dynamic ecosystem of microbes that are essential for preserving vaginal health and avoiding infections. Vaginal dysbiosis has been accompanied with numerous adverse pregnancy complications, such as preterm birth. However, the effect of the vaginal microbiome in miscarriage is not fully understood. This review aims to investigate the link between vaginal microbiota and miscarriage. Also, we investigate the various mechanisms through which the vaginal microbiota may affect miscarriage. Additionally, we examine the implications of these research findings, specifically the possibility of vaginal microbiome screening and targeted interventions to prevent miscarriage.

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.

Lnc-HZ05 regulates BPDE-inhibited human trophoblast cell proliferation and affects the occurrence of miscarriage by directly binding with miR-hz05

Approximately 15-25% pregnant women end with miscarriage in the world. Environmental BaP (benzo(a)pyrene) and its terminal metabolite BPDE (benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide) may result in the dysfunctions of trophoblast cells, which might further lead to RM (recurrent miscarriage). However, potential mechanisms remain unelucidated. In this work, we identified a novel lnc-HZ05 highly expressed and a novel miR-hz05 lowly expressed in both trophoblast cells exposed to BPDE and human RM tissues. MiR-hz05 reduces FOXO3a mRNA level by weakening its mRNA stability. Lnc-HZ05 increases the expression of FOXO3a by acting as a ceRNA for miR-hz05, and then increases P21 level and reduces CDK2 level. Thus, cell cycle is arrested at G0/G1 phase and trophoblast proliferation is inhibited. Lnc-HZ05 harboring wild-type binding site for miR-hz05, but not its mutant site, could upregulate FOXO3a expression. In normal trophoblast cells, relatively less lnc-HZ05 and more miR-hz05 activate FOXO3a/P21/CDK2 pathway and promote trophoblast proliferation, giving normal pregnancy. In RM tissues and BPDE-treated human trophoblast cells, lnc-HZ05 is increased and miR-hz05 is reduced, both of which suppress this pathway and inhibit cell proliferation, and finally lead to miscarriage. Thus, lnc-HZ05 and miR-hz05 simultaneously regulate cell cycle and proliferation of BPDE-exposed trophoblast cells and miscarriage, providing new perspectives and clinical understandings in the occurrence of unexplained miscarriage.

Molecular investigation of association between common IL-6 polymorphism with cytomegalovirus (CMV) infection and recurrent miscarriage in Iranian women

BACKGROUND

Recurrent pregnancy loss (RPL) is described as two or more spontaneous abortions. To date, scientists in various fields of knowledge, such as genetics, endocrinology, anatomy, immunology, and microbiology, have identified some important factors that affect abortions; nonetheless, the precise basic etiology is not determined in up to 50% of RPL cases. Human cytomegalovirus (CMV) infection and host genetic background, like IL-6 SNP polymorphisms, play important roles in RPL etiology.

OBJECTIVE

This study aimed to evaluate the relationships among single nucleotide polymorphisms (-634C/G and -174 G/C) in the IL-6 gene with CMV infection and the risk of RPL for early detection and treatment.

MATERIALS AND METHODS

This case-control study was carried on 80 Iranian females with RPL and 80 healthy females as controls. DNA was extracted from samples and CMV and IL6 SNPs were detected using Tetra ARMS-PCR. Statistics were analyzed by Epi Info TM and SPSS software by X2 test for the roles of CMV detection and two polymorphisms in RPL.

RESULTS

The results indicated an increased rate of CMV infection in the RPL group (44%) compared to the control group (25.45%). The prevalence of IL-6-634C/G genotype among RPL patients with CMV infection was 80%, while the frequency of this genotype among RPL patients without CMV infection was 50%. Furthermore, no substantial relation was found between IL-6-174 G/C genotypes and RPL (p = 0.005).

CONCLUSION

This study not only indicated a significant role for CMV in RPL, but also showed an association between CMV and allele G in IL6-634 among Iranian women. In addition, the findings suggested the use of CMV and IL-6-634 GG genotypes as diagnostic and prognostic biomarkers for RPL in the Iranian population.

Comprehensive Analysis of circRNAs, miRNAs, and mRNAs Expression Profiles and ceRNA Networks in Decidua of Unexplained Recurrent Spontaneous Abortion

The diagnosis and treatment of unexplained recurrent spontaneous abortion (URSA) are subject to debate, because the exact underlying mechanisms remain unclear. To address this issue, we elucidated the expression profiles of dysregulated circRNAs, miRNAs, and mRNAs and constructed circRNA-associated competitive endogenous RNA (ceRNA) networks by comparing the decidua of URSA with that of normal early pregnancy (NEP) using RNA-sequencing. In total, 550 mRNAs, 88 miRNAs, and 139 circRNAs were differentially expressed (DE) in decidua of URSA. Functional annotation revealed that DE mRNAs as well as potential target genes of DE miRNAs and DE circRNAs are mainly involved in immunologic function, such as antigen processing and presentation, allograft rejection, and T cell receptor signaling pathway. In addition, the top hub genes, including CCL4, DDX58, CXCL10, CXCL9, MX1, CD44, RPS2, SOCS3, RPS3A, and CXCL11, were identified. The mRNAs involved in ceRNA network were enriched in complement and coagulation cascades and protein processing in the endoplasmic reticulum. We found that circRNAs in the ceRNA network, which acted as decoys for hsa-miR-204-5p, were positively correlated with MFGE8 expression. Collectively, the results demonstrated that circRNAs, miRNAs, and mRNAs were aberrantly expressed in the decidua of patients with URSA and played a potential role in the development of URSA. Thus, the establishment of the ceRNA network may profoundly affect the diagnosis and therapy of URSA in the future.

Association of Polymorphisms in miR146a, an Inflammation-Associated MicroRNA, with the Risk of Idiopathic Recurrent Spontaneous Miscarriage: A Case-Control Study

It has been established that microRNAs (miRNAs) are involved in the regulation of immune responses and serve as biomarkers of inflammatory diseases as well as recurrent spontaneous miscarriage (RSM). Herein, we aimed to study the relationship between three functional miR146a gene polymorphisms with idiopathic RSM (IRSM) susceptibility. We recruited 161 patients with IRSM and 177 healthy women with at least one live birth and without a history of abortion. Genotyping was performed using RFLP-PCR and ARMS-PCR methods. We found that the rs6864584 T/C decreased the risk of IRSM under dominant TT+TC vs. CC (OR = 0.029) and allelic C vs. T (OR = 0.028) contrast models. Regarding rs2961920 A/C and rs57095329 A/G polymorphisms, the enhanced risk of IRSM was observed under different genetic contrasted models, including the codominant CC vs. AA (OR = 2.81 for rs2961920) and codominant GG vs. AA (OR = 2.36 for rs57095329). After applying a Bonferroni correction, haplotype analysis revealed a 51% decreased risk of IRSM regarding the ACA genotype combination. This is the first study reporting that miR146a rs57095329 A/G, rs2961920A/C, and rs6864584 T/C polymorphisms are associated with the risk of IRSM in a southern Iranian population. Performing replicated case-control studies on other ethnicities is warranted to outline the precise effects of the studied variants on the risk of gestational trophoblastic disorders.

Association of the PECAM-1 (Leu125Val) and P-Selectin (Thr715Pro) Gene Polymorphisms With Unexplained Spontaneous Miscarriages

Introduction: The aim of this study was to investigate the possible effect of the PECAM-1-C373G (Leu125Val) and P-Selectin-A37674C (Thr715Pro) polymorphisms in unexplained spontaneous abortions.

Methods: In a case-control design, Greek nulligravida women with recurrent idiopathic miscarriages <20 weeks of gestation and fertile controls were genotyped by pyrosequencing.

Results: There was no significant association of the PECAM-1-C373G (Leu125Val) polymorphism with recurrent abortions. Although the P-Selectin-A37674C (Thr715Pro) polymorphism was not associated with miscarriages overall, the association was statistically significant for younger women (carriers of the P-Selectin-37674C allele: <35 years: odds ratio (OR) = 3, 95% confidence interval (CI): 1.13-7.97, p = 0.023; <30 years: OR = 6.75, 95%CI: 2.02-22.58, p = 0.002). In comparison with CC/AA genotype, the combined carriers of the PECAM-1-373G and P-Selectin-37674C alleles had OR =8.81 (95%CI: 1.07-72.50, p = 0.024). The association of the coexistence of the two polymorphisms was stronger in younger women (<35 years: OR = 12.07, 95%CI: 1.38-105.68, p = 0.014; <30 years: OR = 65, 95%CI: 3.38-1251.28, p = 0.001), and late (OR = 10.64, 95%CI: 1.16-97.60, p = 0.024) and second-trimester miscarriages (OR = 26, 95%CI: 1.84-367.71, p = 0.014). The association between carriage of the P-Selectin-37674C allele and recurrent miscarriages was significant for younger women.

Conclusion: The coexistence of the PECAM-1-373G and P-Selectin-37674C alleles increased the miscarriage risk for the total population studied, suggesting an interaction between the two polymorphisms, more pronouncedly in younger women and the association was stronger for late fetal loss.

Association between the rs3802201 polymorphism of the lncRNA MIR2052HG gene and the risk of recurrent miscarriage in a Southern Chinese population

BACKGROUND

Plenty of studies have indicated that some genetic polymorphisms of the breast cancer which associated with its susceptibility may also be related to the susceptibility of abortion. MIR2052HG plays an important role in the onset and progression of breast cancer by maintaining the level of ERα, but to the best of our knowledge, the correlation between risk of recurrent abortion and MIR2052HG rs3802201 C>G polymorphism is still unclear. Therefore, we conducted this case-control study to investigate whether MIR2052HG rs3802201 C>G polymorphism is associated with susceptibility of recurrent miscarriage (RM).

METHODS

We recruited 392 healthy controls and 248 patients with RM to process this research, the participants were all from southern China, and genotyping was performed by TaqMan method.

RESULTS

Our results showed that there was no evidence indicates the MIR2052HG rs3802201 C>G is related to RM (CG and CC: adjusted OR = 0.970, 95% CI = 0.694-1.355, p = 0.8577; GG and CC: adjusted OR = 0.743, 95% CI = 0.416-1.330, p = 0.3174; dominant model: adjusted OR = 0.925, 95% CI = 0.672-1.272, p = 0.6298; recessive model: adjusted OR = 0.751, 95% CI = 0.430-1.321, p = 0.3233).

CONCLUSION

We verified that the MIR2052HG rs3802201 C>G allele might be uncorrelated to the RM risk, but these findings require further validation in multicenter studies with larger sample size and different ethnicities.

Can Lactobacillus spp. Be a Factor Reducing the Risk of Miscarriage?

Pregnancy loss is a common obstetric problem. Significant causes of miscarriage include genetic and epigenetic disorders of the embryo, immunological and endocrine factors, uterine malformations, improper embryo selection, and lifestyle. Perhaps a hitherto underappreciated cause of miscarriage may be an abnormal microbiota composition of the female reproductive system. Lactobacillus spp. is the most common bacteria within the reproductive tract. However, the protective role of Lactobacilli in the vagina has been well described in the literature, while it is still unknown what function Lactobacilli may have in the uterus. Moreover, new research shows that Lactobacillus spp. can have a role in miscarriage. However, both molecular and immunological mechanisms of host-Lactobacillus spp. interactions are not fully understood. Understanding these relationships will help address the importance and extent of the protective role of Lactobacillus spp. in miscarriage.

Genetic variants of HOTAIR are associated with susceptibility to recurrent spontaneous abortion: A preliminary case-control study

AIM

To investigate the association between Hox transcript antisenses RNA (HOTAIR) polymorphisms, rs12826786 C/T, rs920778 T/C, rs4759314 A/G, and rs1899663 G/T, with recurrent spontaneous abortion (RSA) susceptibility in the Iranian women.

METHODS

We enrolled 161 patients diagnosed with RSA and 177 healthy women with at least one live birth without a history of abortion. Genotyping of HOTAIR polymorphisms was carried out using both restriction fragment length polymorphism-polymerase chain reaction and amplification refractory mutation system-polymerase chain reaction methods. Odds ratios (ORs) with 95% confidence intervals (CIs) were assessed to estimate the strength of association.

RESULTS

Different inheritance models of rs12826786 C/T, rs920778 T/C, and rs1899663 G/T polymorphisms significantly enhanced the risk of RSA (p < 0.05), whereas the rs4759314 A/G polymorphism was correlated with diminished risk of developing RSA under recessive AA versus GA + GG (OR 0.42 [95% CI = 0.19-0.91]), log-additive GG versus GA vs. GG (OR 0.67 [95% CI = 0.48-0.93]), and allelic A versus G (OR 0.65 [95% CI = 0.47-0.92]) models. Moreover, the TGTC, TTCT, TTTC, CGTC, CGTT, CTCC, CTCT, CTTC, and CTTT haplotypes of rs920778/rs1899663/rs12826786/ significantly increased the risk of RSA. The studied variants were not in strong linkage disequilibrium.

CONCLUSIONS

Our results indicated that variations in the HOTAIR gene might serve as beneficial biomarkers for determining susceptibility to RSA. To confirm these findings, replication studies with a larger population and different races are needed.

Influence of prominent immunomodulatory cytokines TNF-α308 G>A (rs1800629) and TGFβ1 G>C (rs1800471) sequence variations as an important contributing factor in etiopathogenesis of recurrent miscarriages in Kashmiri women (North India)

AIM

We aimed to evaluate the genetic variation of tumor necrosis factor-α (TNF-α) 308 G>A (rs1800629) and transforming growth factor (TGF) β1G>C (rs1800471) to confer risk in patients with recurrent miscarriage in highly consanguineous population of Kashmir (North India).

METHODS

A total of 200 women who experienced two or more recurrent miscarriages (along with 100 spouses, 60 products of conception, and 240 healthy controls) with two or more full-term pregnancies were recruited from the same geographical region and evaluated by polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

TNF-α 308 G>A variant genotype (AA) was significantly associated with recurrent miscarriage cases (2.5% vs. 0.4% controls, respectively; p < 0.05) and its per copy allele A also presented more in cases (32% vs. 24% in controls; p < 0.05) that showed a risk of 1.5-fold for cases (p < 0.05). The difference of variant genotype GA was observed to be significant among recurrent miscarriage cases and product of conception: 60.5% vs. 83%, respectively (p < 0.05) wherein variant TNF-α GA genotype conferred 3-fold risk (p < 0.05). On the other hand, TGF β1 G>C showed no association with recurrent miscarriage cases in our population.

CONCLUSION

The study found both TNF-α 308 G>A variants are significantly associated with an increased susceptibility for recurrent miscarriages to cause pregnancy losses but on the other hand TGF β1 does not seem to impact the outcome of pregnancy in our population.

The SERPINA4 rs2070777 AA Genotype is Associated with an Increased Risk of Recurrent Miscarriage in a Southern Chinese Population

Background

Many inflammation-related gene polymorphisms are associated with susceptibility to recurrent miscarriage. SERPINA4 is involved in inflammation and is associated with susceptibility to a variety of diseases, but its relevance in recurrent miscarriage is unclear. Therefore, this study aimed to investigate the relationship between SERPINA4 gene polymorphisms and susceptibility to recurrent spontaneous abortion.

Methods

Two SERPINA4 polymorphisms were genotyped in 631 patients with recurrent miscarriage and 771 controls by TaqMan real-time polymerase chain reaction, and the strength of each association was evaluated through 95% confidence intervals (CIs) and odds ratios (ORs).

Results

The results showed that SERPINA4 rs2070777 AA genotypes were associated with an increased risk of recurrent miscarriage (AA vs AT/TT adjusted OR=1.409, 95% CI=1.032–1.924, P=0.0309), and we also found a significant association between the rs910352 T allele in the SERPINA4 gene and susceptibility to recurrent miscarriage (CT vs CC adjusted OR=1.579, 95% CI=1.252–1.992, P=0.0001; TT vs CC adjusted OR=1.524, 95% CI=1.134–2.049, P=0.0052). The combined analysis of two SNPs of the SERPINA4 gene revealed that carriers with one to two unfavorable genotypes were associated with a higher risk for recurrent miscarriage compared with individuals with no unfavorable genotypes (adjusted OR=1.257, 95% CI=1.019-1.550). Moreover, our study indicates that having one to two unfavorable genotypes is associated with an increased risk of recurrent miscarriage in women 35–40 years of age.

Conclusion

Our study suggests that SERPINA4 rs2070777AA genotypes might contribute to an increased risk of recurrent miscarriage in a southern Chinese population.

The alteration and potential relationship of vaginal microbiota and chemokines for unexplained recurrent spontaneous abortion

The diagnosis and treatment of unexplained recurrent spontaneous abortion (URSA) is an important and hot topic in the field of obstetrics and gynecology. During our clinical investigation (observation), we have found that URSA patients usually experience recurrent vaginitis or vaginal dysbacteriosis during periods of non-pregnancy, pregnancy, and post-abortion. However, there is no research on vaginal dysbacteriosis's influence on URSA. Using women with normal induced abortion as a control group, and using 16S rRNA sequencing, which helps to screen differentially expressed flora, this study discusses the relevance between differential bacteria at the genus level and the incidence of URSA. Another aim of this study is to determine whether certain pathogenic genera can cause an imbalance in immune tolerance of the maternal and fetal interface through regulatory chemokines, which leads to recurrent spontaneous abortion. This article has explored URSA pathogenesis from the perspective of differentially expressed vaginal flora, which has great theoretical significance for the early diagnosis and treatment of URSA.

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

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

Association of Killer Immunoglobulin-Like Receptor and Human Leukocyte Antigen Class I Ligand with Recurrent Abortion in Saudi Women

Aims: This study was designed to determine whether genetic polymorphisms of the killer immunoglobulin-like receptor (KIR) and human leukocyte antigen class I (HLA-C) genes are associated with recurrent spontaneous abortion (RSA) in Saudi women. Materials and Methods: Sixty-five healthy women with a history of RSA (three or more spontaneous abortions) and 65 healthy controls (with two or more healthy-born children) living in Riyadh were typed for 17 KIR genes and the HLA-C1 and HLA-C2 allotypes using polymerase chain reaction-sequence-specific primer methodology. Results: The frequencies of KIR2DS2 and KIR2DL5A were significantly lower among RSA women compared to healthy controls (odds ratio [OR] = 0.17; p < 0.001; OR = 0.16; p < 0.001, respectively). No association with maternal HLA-C genotypes was observed. Analysis of KIR-HLA-C combinations indicated a protective effect of KIR2DS2 with its cognate HLA-C1 ligand in both homozygote or heterozygote combinations. Conclusion: Our results demonstrate that the KIR genes of the B haplotype may play an important role in ensuring the success of pregnancy.

Association of IL-1β, IL-6, TNF-α, and TGFβ1 Gene Polymorphisms with Recurrent Spontaneous Abortion in Polycystic Ovary Syndrome

Recurrent spontaneous abortion (RSA) is a common pregnancy-associated complication of polycystic ovary syndrome (PCOS) which is an endocrine malfunction disease. Patients with PCOS may have several underlying contributing and interrelated factors, which have been reported in women with RSA. The incidence rate between PCOS and RSA remains uncertain. The aim of this study is to determine the possible association of IL-1β-511C/T, IL-6-174G/C, TNF-α-1031T/C, and TGFβ1-509T/C with RSA patients with or without PCOS. A total of 140 RSA patients, 70 of which were PCOS patients, and 140 healthy females with no history of RSA or PCOS were included in this study. PCR amplification, genotyping, and sequence analysis were employed to investigate the presence of the polymorphisms. The genotypic and allelic frequencies were calculated separately for each subject. Out of the four studied polymorphisms, the IL-1β-511C/T genotype in RSA without PCOS patients (12.7%) was significantly different compared with that in control subjects (p = 0.047). For IL-6-174C/G, there was a tendency towards more CC carriers among RSA with PCOS patients (10%) than in controls (3%). The GG genotype in RSA women with PCOS (60%) was significantly different compared with that in control subjects (p = 0.033), and the GC genotype in RSA with PCOS patients (30%) showed a marginal significant difference compared with that in control subjects (p = 0.050). Significant difference was identified in the allelic frequencies in RSA patients with PCOS compared to controls (p = 0.025). IL-6-174G/C and TNF-α-1031T/C polymorphisms are significantly associated with RSA patients in Saudi patients with PCOS, while the IL-1β-511C/T polymorphism is significantly associated with RSA patients without PCOS.

Pregnancy complications recur independently of maternal vascular malperfusion lesions

BACKGROUND

Spontaneous abortions, intrauterine growth restriction, and preeclampsia are thought to be caused by defective placentation and are associated with increased risk of adverse outcomes in subsequent pregnancies. However, it is not known whether the recurrence of adverse outcomes is associated with the recurrence of placental pathology. We hypothesized that recurrent maternal vascular malperfusion (MVM) underlies the recurrence of adverse outcomes.

METHODS

Using data from the National Collaborative Perinatal Project, we assessed the recurrence of pregnancy complications and MVM lesions (N = 3865), associations between a history of spontaneous abortions and MVM lesions or adverse outcomes in subsequent pregnancies (N = 8312), and whether the recurrence of pregnancy complications occurred independently of the presence of MVM lesions.

RESULTS

The odds of an MVM lesion were higher for a woman who had had an MVM lesion in a previous pregnancy (aOR = 1.6; 95% CI 1.3-1.9), although this was marginally non-significant after adjusting for covariates such as gestational age, race and BMI. The odds of preeclampsia, a small-for-gestational-age infant, premature delivery and early pregnancy loss were 2.7-5.0 times higher if there had been that same adverse outcome in a previous pregnancy. A history of spontaneous abortions was associated with higher risk of a small-for-gestational-age baby (aOR = 2.4; 95% CI 1.7-3.4) and prematurity (aOR = 5.1; 95% CI 2.3-11.5 for extremely preterm), but not preeclampsia. The recurrence of adverse outcomes was significant when restricting analyses to women without MVM lesions. Similarly, associations between adverse outcomes and previous spontaneous abortions were significant when statistically controlling for the presence of MVM lesions, or excluding pregnancies with MVM lesions.

CONCLUSIONS

Women with adverse outcomes in one pregnancy are at higher risk of complications in subsequent pregnancies. However, there is significant recurrence of adverse outcomes even in the absence of MVM.

Unpasteurised milk consumption as a potential risk factor for toxoplasmosis in females with recurrent pregnancy loss

In women with a bad obstetric history, certain infections are associated with recurrent foetal loss. One of the common infectious agents is a protozoan parasite, Toxoplasma gondii. The aim of this study was to assess unpasteurised milk consumption as a potential risk factor for toxoplasmosis in females with recurrent pregnancy loss from the province of Khyber Pakhtunkhwa, Pakistan. In this study, we recruited a total of 360 females, comprising a study group of 180 females with previous history of recurrent pregnancy loss and a control group of 180 females with no such history. Blood serum from the participants was analysed for Toxoplasma gondii IgM antibodies by enzyme linked immunosorbent assay. Among the study group, 23 (12.8%) females were serologically positive for IgM antibodies against Toxoplasma gondii, whilst 157 (87.2%) were IgM negative. In the control group, only two (4.8%) females were IgM positive, whilst 178 (95.2%) were IgM negative. Bad pregnancy outcome in the study group and control group was observed to be significantly different (p < .0001). In both of these groups, unpasteurised milk consumption was found as a major risk factor for Toxoplasma gondii infection. A routine serological investigation should be carried out in pregnant women to rule out toxoplasmosis and reduce the risk of recurrent pregnancy loss as well as congenital toxoplasmosis in newborns.Impact statementWhat is already known on this subject? Seropositivity for Toxoplasma gondii antibodies ranges from 7% to 51% in different regions of the world. The prevalence rate varies because of differences in climate, culture, food habits, behaviour, personal hygiene and cooking habits of different societies and ethnic groups. Various risk factors have been identified that contribute to a high prevalence rate of the disease, including consumption of raw or poorly cooked meat, physical contact with cats or cat litter, consumption of unwashed raw vegetables and fruits, drinking of contaminated water and milk. We presumed that consuming unpasteurised milk could be a potential risk factor for developing toxoplasmosis in pregnant women.What the results of this study add? This study demonstrates high seroprevalence of Toxoplasma gondii antibodies in females of child bearing age that have consumed unpasteurised milk and is a potential risk factor for developing toxoplasmosis.What the implications are of these findings for clinical practice and/or further research? Our findings suggest that primary preventive measures (personal hygiene, frequent hand washing and consuming pasteurised milk) should be taken by health surveillance authorities to focus on families, especially pregnant women, to educate them about personal hygiene, contact with cattle or using their milk and milk products. The latter is especially important to aware them about the hazards of consuming unpasteurised and contaminated milk.

Defining the role of FMR1 gene in unexplained recurrent spontaneous abortion

INTRODUCTION

Recurrent spontaneous abortion is a multifactorial disorder and till date, various factors have been attributed in its pathogenesis. Still, approximately 50% of RSA cases remain unexplained. Premutation (PM) expanded allele of fragile-X mental retardation 1 (FMR1) gene is known to contribute to ovarian dysfunction in 20% of the cases. Recently, the link between expanded FMR1 allele and recurrent miscarriages has been reported.

METHOD

In the present prospective case-control study, we have investigated the status of CGG repeat size at 5'UTR of the FMR1 gene in women with unexplained RSA in comparison to age-matched healthy control women (n = 100 each). The genomic DNA from these samples was subjected to molecular analysis for characterization of CGG repeat size and composition at FMR1 gene RESULTS: As compared to the control women, the RSA women cohort had a higher frequency of carriers with alleles in gray zone (GZ) and expanded PM range, i.e., 2% (2/100) versus 5% (5/100), respectively. Also, the RSA cohort had a significantly higher number of normal alleles with ≥ 35 CGG repeats (24 out of 200 alleles) as compared to control cohort (8 out of 200 alleles). The number of larger FMR1 alleles with pure CGG repeat tract was found to be significantly higher (P = 0.0063) in the RSA cohort (15 out of 200 alleles) as compared to that in control cohort (3 out of 200 alleles).

CONCLUSION

Henceforth, the CGG expanded uninterrupted FMR1 allele might be associated with recurrent abortions and may help to explain many of these unexplained cases.

Association between the TOX3 rs3803662 C>T polymorphism and recurrent miscarriage in a southern Chinese population

BACKGROUND

Studies have shown that some genetic polymorphisms associated with breast cancer susceptibility may also be associated with abortion. The TOX3 gene plays a key role during the onset of breast cancer, and reproductive factors such as abortion are risk factors for breast cancer. However, there is currently no study describing the relationship between the TOX3 rs3803662 C>T polymorphism and the risk of recurrent miscarriage. Therefore, we investigated whether the TOX3 rs3803662 C>T polymorphism is associated with recurrent miscarriage susceptibility in this case-control study.

METHODS

We recruited 248 recurrent miscarriage patients and 392 healthy controls from the southern Chinese population and performed genotyping using the TaqMan method.

RESULTS

The results showed no evidence that TOX3 rs3803662 C>T is associated with recurrent miscarriage (CT and CC: corrected OR = 1.038, 95% CI = 0.737-1.461, P = .8321; TT and CC: adjusted OR = 0.989, 95% CI = 0.591-1.656, P = .9659; dominant model: adjusted OR = 1.027, 95% CI = 0.742-1.423, P = .8712; recessive model: adjusted OR = 0.969, 95% CI = 0.600-1.566, P = .8975).

CONCLUSION

According to this study, the TOX3 rs3803662 C>T polymorphism may not be associated with recurrent miscarriage in the southern Chinese population. A larger multicenter study is needed to confirm the results.

The association of Q472H variant in the KDR gene with recurrent pregnancy loss in Southern Iran: A case-control study

Background

Recurrent spontaneous abortion (RSA) often remains unclear and can be burden for the patient and time consuming for clinician. RSA may initiates from a genetic or non-genetic factors. It is well known that the quality of placental circulation is critical for implantation and embryo development. Because of angiogenic effects of VEGF–KDR pathway on placenta, the genes involved in this pathway (the KDR or VEGFR genes) are thought to be linked with RSA.

Objective

The aim of this study was to investigate the relationship between Gln472His (A/T) polymorphism of the KDR gene with RSAs in southern Iran.

Materials and Methods

In this case-control study, 50 aborted embryonic tissue obtained from fetuses and 50 umbilical cord blood of newborn babies were studied. Fetal sample from mothers with history of at least two consecutive miscarriages and controls from mothers who had at least one full-term infants born were taken. Genomic DNA was extracted by using PureLink genomic DNA kit (Life Technologies, CA). The Rotor-Gene Q real-Time PCR machine and High-resolution melting curve analysis (HRM) technique were used for genotyping.

Results

Based on the AA genotype as reference, it is shown that the T allele (OR = 2.447, 95% CI = 1.095–5.468, p = 0.029) as well as AT heterozygote genotype was significantly associated with an increased risk of miscarriage (OR = 2.824, 95% CI = 1.210-6.673, p = 0.016).

Conclusion

A positive correlation between Q472H polymorphism of the KDR gene and RSA may be the cause in southern Iran.

Polymorphisms in interleukin genes and their association with the risk of recurrent pregnancy loss

Interleukins play important roles in pregnancy. Altered expression and splicing of various interleukins have been linked to the pathophysiology of recurrent pregnancy loss. Polymorphisms in interleukin genes can affect the expression and/or splicing of their respective genes and thus influence the risk of recurrent pregnancy loss. In this work, we examined the association between the IL1B rs16944, IL1B rs1143634, IL6 rs1800795, IL6 rs1800796, IL10 rs1800896 and IL18 rs187238 polymorphisms and recurrent pregnancy loss risk in a Chinese population. Study subjects comprised 598 idiopathic recurrent pregnancy loss patients and 603 controls. The genotyping was accomplished by PCR-RFLP. Regression analysis was performed to evaluate the disease association. After adjustment by Bonferroni correction, only the IL1B rs16944 and IL6 rs1800796 polymorphisms were significantly associated with risk of recurrent pregnancy loss. The heterozygous TC genotype of IL1B rs16944 had an adjusted odds ratio (aOR) of 1.4209 (1.1302-1.8929) (P = 0.0019), while the homozygous CC genotype had an aOR of 1.7398 (1.2133-2.3203) (P = 0.0008). A significant association was also observed for the C allele [aOR = 1.3747 (1.1296-1.8972)] (P = 0.0003). For IL6 rs1800796, the heterozygous CG genotype, the homozygous GG genotype and the G allele had aORs of 0.7342 (0.4412-0.8423) (P = 0.0016), 0.5424 (0.1768-0.7865) (P = 0.0014) and 0.7009 (0.4511-0.8034) (P = 0.0007), respectively. In summary, the IL1B rs16944 and IL6 rs1800796 variants were associated with an increased and a decreased recurrent pregnancy loss risk, respectively.

Interleukin-3 Polymorphism is Associated with Miscarriage of Fresh in Vitro Fertilization Cycles

The aim of this study was to examine the association between interleukin (IL) genes polymorphisms and in vitro fertilization (IVF) outcome. A prospective cohort analysis was performed at a Women’s Hospital IVF centre of 1015 female patients undergoing fresh non-donor IVF cycles. The effects of the following six single nucleotide polymorphisms (SNPs) in five IL genes on IVF outcomes were explored: IL-1α (rs1800587 C/T), IL-3 (rs40401 C/T), IL-6 (rs1800795 C/G), IL-15 (rs3806798 A/T), IL-18 (rs187238 C/G) and IL-18 (rs1946518 G/T). The main outcome measures included clinical pregnancy, embryo implantation, abortion and live birth rates. There were no statistically significant differences in clinical pregnancy, embryo implantation and live birth rates in the analysis of 1015 patients attempting their first cycle of IVF. Infertile women with IL-3 homozygous major genotype had a higher abortion rate than those with heterozygous and homozygous minor genotype (16.5% vs. 7.9%, P = 0.025). In conclusion, our results indicated that the IL-3 rs40401 polymorphism is associated with increased risk of abortion of IVF patients. Future studies with inclusion of other ethnic populations must be conducted to confirm the findings of this study.

Effects of Single-Nucleotide Polymorphisms in Cytokine, Toll-Like Receptor, and Progesterone Receptor Genes on Risk of Miscarriage

Spontaneous abortion is a complex, multifactorial pathology, where various genetic, neural, endocrine, and immunological factors are involved. Cytokines, Toll-like receptors, and progesterone receptors play critical roles in embryonic implantation and development. A delicate, stage-specific equilibrium of these proteins is required for successful pregnancy outcome. However, genetic variation from one individual to another results in variation in levels of Th1/Th2 cytokines, strength of identification of infectious agents by Toll-like receptors, and quality of progesterone recognition. Thus, a complex study encompassing effects of major SNPs of cytokine, TLR, and PGR genes on the risk of miscarriage is needed. In this study, we investigated SNPs of 9 genes (TLR2 G753A, TLR4 C399T, TLR9 G2848A, TGF-β1 C509T, PGR PROGINS, IL-6 G174C, IL-8 C781T, IL-10 C592A, and TNFα G308A) in 106 women, whose pregnancy ended in miscarriage, and 74 women, who delivered in term without any pregnancy complication. All participants are from Ukrainian population. As a result, TLR9 and IL-10 SNPs have been found to play critical roles in the development of spontaneous abortion. TLR2, TLR4, IL-6, IL-8, and PGR SNPs were identified as secondary factors that can also affect the risk of miscarriage. There was no association found between TGF-β1 and TNFα polymorphisms and miscarriage.

Genetic variation in the CLOCK gene is associated with idiopathic recurrent spontaneous abortion

Physiological studies in animals and human support an important role of circadian system in reproduction. The aim of this study was to investigate the potential association of CLOCK gene polymorphisms with idiopathic recurrent spontaneous abortion (IRSA). We performed a case-control study. The study group consisted of 268 women with a history of three or more idiopathic recurrent spontaneous abortions and 284 women with at least two live births and no history of pathologic pregnancies all from Slovenia and Serbia. Two SNPs in the CLOCK gene were chosen and genotyped. The results showed a statistically significant difference in genotype distribution between the two groups in the CLOCK gene for rs6850524 and rs11932595. Our analysis showed that G allele under dominant model (GG+GC/CC) for rs6850524 (p = 2∙10-4, OR = 2.28, 95%CI = 1.46-3.56) as well as G allele under dominant model (GA+AA/AA) for rs11932595 (p = 0.04, OR = 1.47, 95%CI = 1.01-2.04) might be risk factors against IRSA. Our data suggest that genetic variability in the CLOCK gene is associated with IRSA warranting further confirmation and mechanistic investigations.

Association of FOXD1 variants with adverse pregnancy outcomes in mice and humans

Recurrent spontaneous abortion (RSA) is a common cause of infertility, but previous attempts at identifying RSA causative genes have been relatively unsuccessful. Such failure to describe RSA aetiological genes might be explained by the fact that reproductive phenotypes should be considered as quantitative traits resulting from the intricate interaction of numerous genetic, epigenetic and environmental factors. Here, we studied an interspecific recombinant congenic strain (IRCS) of Mus musculus from the C57BL6/J strain of mice harbouring an approximate 5 Mb DNA fragment from chromosome 13 from Mus spretus mice (66H-MMU13 strain), with a high rate of embryonic resorption (ER). Transcriptome analyses of endometrial and placental tissues from these mice showed a deregulation of many genes associated with the coagulation and inflammatory response pathways. Bioinformatics approaches led us to select Foxd1 as a candidate gene potentially related to ER and RSA. Sequencing analysis of Foxd1 in the 66H-MMU13 strain, and in 556 women affected by RSA and 271 controls revealed non-synonymous sequence variants. In vitro assays revealed that some led to perturbations in FOXD1 transactivation properties on promoters of genes having key roles during implantation/placentation, suggesting a role of this gene in mammalian implantation processes.

Novel genes and mutations in patients affected by recurrent pregnancy loss

Recurrent pregnancy loss is a frequently occurring human infertility-related disease affecting ~1% of women. It has been estimated that the cause remains unexplained in >50% cases which strongly suggests that genetic factors may contribute towards the phenotype. Concerning its molecular aetiology numerous studies have had limited success in identifying the disease's genetic causes. This might have been due to the fact that hundreds of genes are involved in each physiological step necessary for guaranteeing reproductive success in mammals. In such scenario, next generation sequencing provides a potentially interesting tool for research into recurrent pregnancy loss causative mutations. The present study involved whole-exome sequencing and an innovative bioinformatics analysis, for the first time, in 49 unrelated women affected by recurrent pregnancy loss. We identified 27 coding variants (22 genes) potentially related to the phenotype (41% of patients). The affected genes, which were enriched by potentially deleterious sequence variants, belonged to distinct molecular cascades playing key roles in implantation/pregnancy biology. Using a quantum chemical approach method we established that mutations in MMP-10 and FGA proteins led to substantial energetic modifications suggesting an impact on their functions and/or stability. The next generation sequencing and bioinformatics approaches presented here represent an efficient way to find mutations, having potentially moderate/strong functional effects, associated with recurrent pregnancy loss aetiology. We consider that some of these variants (and genes) represent probable future biomarkers for recurrent pregnancy loss.

Priorities for research in miscarriage: a priority setting partnership between people affected by miscarriage and professionals following the James Lind Alliance methodology

OBJECTIVES

To identify and prioritise important research questions for miscarriage.

DESIGN

A priority setting partnership using prospective surveys and consensus meetings following methods advocated by the James Lind Alliance.

SETTING

UK.

PARTICIPANTS

Women and those affected by miscarriage working alongside healthcare professionals.

RESULTS

In the initial survey, 1093 participants (932 women who have experienced miscarriage, 8 partners, 17 family members, friends or colleagues, 104 healthcare professionals and eight charitable organisations) submitted 3279 questions. A review of existing literature identified a further 64. Non-questions were removed, and the remaining questions were categorised and summarised into 58 questions. In an interim electronic survey, 2122 respondents chose their top 10 priorities from the 58 summary questions. The 25 highest ranked in the survey were prioritised at a final face-to-face workshop. In summary, the top 10 priorities were ranked as follows: research into preventative treatment, emotional aspects in general, investigation, relevance of pre-existing medical conditions, emotional support as a treatment, importance of lifestyle factors, importance of genetic and chromosomal causes, preconception tests, investigation after different numbers of miscarriage and male causal factors.

CONCLUSIONS

These results should be the focus of future miscarriage research. Presently, studies are being conducted to address the top priority; however, many other priorities, especially psychological and emotional support, are less well researched areas. We hope our results will encourage both researchers and funders to focus on these priorities.

Genetics of recurrent miscarriage and fetal loss

Despite years of research, miscarriage, particularly when recurrent, continues to pose a medical challenge. An embryo chromosomal error is responsible for 50-60% of recurrent cases; however, up to 30-50% remains an enigma. Successful pregnancy involves different maternal physiologic changes and certain complex interactions between the fetus and the mother by cytokines, angiogenic mediators and hormones. To date, research lines have focused on genetic and epigenetic polymorphisms related mainly to immune response and inflammatory mediators, and have yielded a significant relationship between recurrent miscarriage and immune mechanisms. Thus, unknown causes of miscarriage could be due to an immune imbalance induced by T-helper Th1/Th2/Th17 cytokines and regulatory T cells. Furthermore, these genes and mediators have long been suspected of being blood markers for the clinical diagnosis and management of miscarriage; however, more evidence is required for them to be included in medical practice and obstetric guidelines.

Immunogenetic contributions to recurrent pregnancy loss

While sporadic pregnancy loss is common, occurring in 15 % of pregnancies, recurrent pregnancy loss (RPL) impacts approximately 5 % of couples. Though multiple causes are known (including structural, hormonal, infectious, autoimmune, and thrombophilic causes), after evaluation, roughly half of all cases remain unexplained. The idiopathic RPL cases pose a challenging therapeutic dilemma in addition to incurring much physical and emotional morbidity. Immunogenetic causes have been postulated to contribute to these cases of RPL. Natural Killer cell, T cell expression pattern changes in the endometrium have both been shown in patients with RPL. Human leukocyte antigen (HLA) and cytokine allelic variations have also been studied as etiologies for RPL. Some of the results have been promising, however the studies are small and have not yet put forth outcomes that would change our current diagnosis and management of RPL. Larger database studies are needed with stricter control criteria before reasonable conclusions can be drawn.

Lack of Association between Angiotensin Converting Enzyme I/D Polymorphism and Unexplained Recurrent Miscarriage in Saudi Arabia

BACKGROUND

An insertion/deletion (I/D) polymorphism in the angiotensin converting enzyme (ACE) gene has been associated with recurrent miscarriage (RM) in several populations. We initiated this study to determine the association, if any, between the I/D polymorphism of ACE gene and RM in Saudi females.

METHOD

This study was conducted on 61 Saudi females suffering from RM (mean age: 34.1±6.2 years; range 15-45) attending clinics at King Khalid University Hospital, and 59 age matched females who had at least 2 children, as controls. Blood samples were drawn in EDTA tubes by venipuncture. DNA was extracted using the Puregene DNA purification kits. Insertion/Deletion (I/D) polymorphism of ACE gene was investigated by amplifying the genomic DNA by PCR using gene-specific primers. A single 190 bp or 490 bp band was obtained in the homozygous cases for the D allele or I allele, respectively, while the presence of both 190 and 490 bp bands indicated heterozygosity (ID).

STATISTICAL ANALYSIS

Deviation from Hardy-Weinberg equilibrium was determined (http://ihg.gsf.de/cgi-bin/hw/hwa1.pl). A standard chi-square (χ²) test was used for comparing the genotype and allele frequencies in the two groups and Students't' test and χ² test were employed to compare values between the two groups. P<0.05 was considered statistically significant.

RESULTS

The frequencies of DD, ID, and II genotypes were 56.7%, 29.5% and 4.9%, respectively, in females with RM and 54.2%, 42.3% and 3.3% respectively in the control group, but the difference was not statistically significant.

CONCLUSION

In some populations, meta-analyses showed an association between I/D polymorphism and RM risk, and the D allele was implicated as an increased risk factor for RM. However, this association was not apparent in the Saudi females.

Association between trefoil factor 3 gene variants and idiopathic recurrent spontaneous abortion

Trefoil factor 3 (TFF3) gene is an inflammatory mediator expressed in human endometrium during the window of implantation. The aim of this study was to evaluate the possible genetic association of TFF3 variants in recurrent spontaneous abortion. Women with a history of recurrent spontaneous abortion (n = 164) and healthy pregnant women (n = 143) were genotyped for five TFF3 polymorphisms (rs225439 G/A, rs533093 C/T, rs225361 A/G, rs11701143 T/C and rs77436142 G/C). In addition, haplotypes formed within the gene were analysed. Within the recurrent spontaneous abortion group, women who at some point had given birth and childless women had 4.19 ± 1.75 and 5.34 ± 3.42 consecutive spontaneous abortions, respectively. Women who had experience recurrent spontaneous abortions had a lower allele frequency of the rs11701143 promoter region minor C allele compared with fertile women (0.02 versus 0.05, P = 0.015). Patients with rs225361 AG genotype had significantly more successful pregnancies before spontaneous abortion than those with homozygous AA and GG genotypes (P = 0.014). No significant differences in haplotype frequencies between patients and controls were detected. Possible genetic risk factors identified that might contribute to the pathogenesis of idiopathic recurrent spontaneous abortion were TFF3 gene variants.

Recurrent spontaneous miscarriage is still a challenging diagnostic and therapeutic quagmire

Recurrent spontaneous miscarriage (RSM), affecting 1-2% of women of reproductive age seeking pregnancy, has been a clinical quagmire and a formidable challenge for the treating physician. There are many areas of controversy in the definition, aetiology, investigations and treatment of RSM. This review will address the many factors involved in the aetiology of RSM which is multifactorial in many patients, with antiphospholipid syndrome (APS) being the most recognized aetiological factor. There is no identifiable cause in about 40-60% of these patients, in which case the condition is classified as idiopathic or unexplained RSM. The RSM investigations are extensive and should be undertaken in dedicated, specialized, well-equipped clinics/centres where services are provided by trained specialists. The challenges faced by the treating physician are even more overwhelming regarding the decision of what should be the most appropriate therapy offered to patients with RSM. Our review will cover the diverse modalities of therapy available including the role of preimplantation genetic testing using recent microarray technology, such as single nucleotide polymorphism and comparative genomic hybridization, as well as preimplantation genetic diagnosis; the greatest emphasis will be on the treatment of APS, and there will be important comments on the management of patients presenting with idiopathic RSM. The controversial areas of the role of natural killer cells in RSM, the varied modalities in the management of idiopathic RSM and the need for better-planned studies will be covered as well.

No evidence for mutations in NLRP7, NLRP2 or KHDC3L in women with unexplained recurrent pregnancy loss or infertility

STUDY QUESTION

Are mutations in NLRP2/7 (NACHT, LRR and PYD domains-containing protein 2/7) or KHDC3L (KH Domain Containing 3 Like) associated with recurrent pregnancy loss (RPL) or infertility?

SUMMARY ANSWER

We found no evidence for mutations in NLRP2/7 or KHDC3L in unexplained RPL or infertility.

WHAT IS KNOWN ALREADY

Mutations in NLRP7 and KHDC3L are known to cause biparental hydatidiform moles (BiHMs), a rare form of pregnancy loss. NLRP2, while not associated with the BiHM pathology, is known to cause recurrent Beckwith Weidemann Syndrome (BWS).

STUDY DESIGN, SIZE, AND DURATION

Ninety-four patients with well characterized, unexplained infertility were recruited over a 9-year period from three IVF clinics in Sweden. Blood samples from 24 patients with 3 or more consecutive miscarriages of unknown etiology were provided by the Recurrent Miscarriage Clinic at St Mary's Hospital, London, UK.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients were recruited into both cohorts following extensive clinical studies. Genomic DNA was isolated from peripheral blood and subject to Sanger sequencing of NLRP2, NLRP7 and KHDC3L. Sequence electropherograms were analyzed by Sequencher v5.0 software and variants compared with those observed in the 1000 Genomes, single nucleotide polymorphism database (dbSNP) and HapMap databases. Functional effects of non-synonymous variants were predicted using Polyphen-2 and sorting intolerant from tolerant (SIFT).

MAIN RESULTS AND THE ROLE OF CHANCE

No disease-causing mutations were identified in NLRP2, NLRP7 and KHDC3L in our cohorts of unexplained infertility and RPL.

LIMITATIONS, REASONS FOR CAUTION

Due to the limited patient size, it is difficult to conclude if the low frequency single nucleotide polymorphisms observed in the present study are causative of the phenotype. The design of the present study therefore is only capable of detecting highly penetrant mutations.

WIDER IMPLICATIONS OF THE FINDINGS

The present study supports the hypothesis that mutations in NLRP7 and KHDC3L are specific for the BiHM phenotype and do not play a role in other adverse reproductive outcomes. Furthermore, to date, mutations in NLRP2 have only been associated with the imprinting disorder BWS in offspring and there is no evidence for a role in molar pregnancies, RPL or unexplained infertility.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by the following sources: Estonian Ministry of Education and Research (Grant SF0180044s09), Enterprise Estonia (Grant EU30020); Mentored Resident research project (Department of Obstetrics and Gynecology, Baylor College of Medicine); Imperial NIHR Biomedical Research Centre; Grant Number C06RR029965 from the National Center for Research Resources (NCCR; NIH). No competing interests declared.

The histidine-rich glycoprotein A1042G polymorphism and recurrent miscarriage: a pilot study

BACKGROUND

Histidine-rich glycoprotein (HRG) has previously been shown to have an impact on implantation and fertility. The aim of this study was to investigate if there is an association between the HRG A1042G single nucleotide polymorphism (SNP) and recurrent miscarriage.

METHODS

The study was designed as a case-control study and the women were included at University Hospitals in Sweden. 186 cases with recurrent miscarriage were compared with 380 pregnant controls with no history of miscarriage. Each woman was genotyped for the HRG A1042G SNP.

RESULTS

The results indicated that the frequency of heterozygous HRG A1042G carriers was higher among controls compared to cases (34.7% vs 26.3%; p<0.05). In a bivariate regression analysis, a negative association was found between recurrent miscarriage and heterozygous A/G carriers both in the entire study population (OR 0.67, 95% CI 0.45 - 0.99; p<0.05) as well as in a subgroup of women with primary recurrent miscarriage (OR 0.37, 95% CI 0.16 - 0.84; p<0.05). These results remained even after adjustment for known confounders such as age, BMI and thyroid disease (OR 0.36, 95% CI 0.15 - 0.84; p<0.05).

CONCLUSIONS

Women who are heterozygous carriers of the HRG A1042G SNP suffer from recurrent miscarriage more seldom than homozygous carriers. Thus, analysis of the HRG A1042G SNP might be of importance for individual counseling regarding miscarriage.

Significant association between angiotensin-converting enzyme gene insertion/deletion polymorphism and risk of recurrent miscarriage: a systematic review and meta-analysis

BACKGROUND

Many studies have investigated the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and risk of recurrent miscarriage, but the impact is unclear due to inconsistencies among those studies. This study aimed to quantify the strength of the association between ACE I/D polymorphism and recurrent miscarriage risk by performing a systematic review and meta-analysis.

DESIGN AND METHODS

We searched PubMed, Embase, Web of Science, and Wanfang Medicine databases for eligible articles relating the association between ACE I/D polymorphism and risk of recurrent miscarriage in humans. We estimated the summary odds ratios (ORs) with their 95% confidence intervals (95% CIs) to assess the association.

RESULTS

Eleven studies with a total of 3357 individuals were included in this meta-analysis. Compared to the ACE II genotype, DD and ID were both associated with increased risk of recurrent miscarriage (OR DD versus II=1.81, 95% CI 1.23-2.66, P=0.003; OR ID versus II=1.50, 95% CI 1.25-1.80, P<0.001). Sensitivity analyses further confirmed the association above. No evidence of publication bias was observed.

CONCLUSION

Meta-analyses of available data show a significant association between ACE I/D polymorphism and recurrent miscarriage risk, and the ACE polymorphic D allele contributes to increased risk of recurrent miscarriage.

New insights into mechanisms behind miscarriage

Sporadic miscarriage is the most common complication of early pregnancy. Two or three consecutive pregnancy losses is a less common phenomenon, and this is considered a distinct disease entity. Sporadic miscarriages are considered to primarily represent failure of abnormal embryos to progress to viability. Recurrent miscarriage is thought to have multiple etiologies, including parental chromosomal anomalies, maternal thrombophilic disorders, immune dysfunction and various endocrine disturbances. However, none of these conditions is specific to recurrent miscarriage or always associated with repeated early pregnancy loss. In recent years, new theories about the mechanisms behind sporadic and recurrent miscarriage have emerged. Epidemiological and genetic studies suggest a multifactorial background where immunological dysregulation in pregnancy may play a role, as well as lifestyle factors and changes in sperm DNA integrity. Recent experimental evidence has led to the concept that the decidualized endometrium acts as biosensor of embryo quality, which if disrupted, may lead to implantation of embryos destined to miscarry. These new insights into the mechanisms behind miscarriage offer the prospect of novel effective interventions that may prevent this distressing condition.

Histidine-rich glycoprotein gene polymorphism in patients with recurrent miscarriage

Association between the histidine-rich glycoprotein (HRG) C633T single nucleotide polymorphism (SNP) and recurrent miscarriage was investigated in a case-control study. The cases constituted 187 women with recurrent miscarriage that were compared with 395 controls who had delivered a child and had no history of miscarriage. Blood samples were collected from each woman, genomic DNA was extracted and genotyped for the HRG C633T SNP. In the whole study population, the percentage of miscarriage was the same, regardless of genotype (C/C 31.2%, C/T 32.9% and T/T 32.5%). However, an association between homozygous T/T carriers and recurrent miscarriage was detected in a subgroup of women with primary recurrent miscarriage (odds ratio 2.44, 95% CI 1.01-5.92). Our results indicate an important role for the HRG C633T SNP in the occurrence of recurrent miscarriage.