Maternal genetic polymorphisms and unexplained recurrent miscarriage: a systematic review and meta-analysis

Systematic review and meta-analysis of association between plasminogen activator inhibitor-1 4G/5G polymorphism and recurrent pregnancy loss: an update

BACKGROUND

We conducted this systematic review and meta-analysis to better understand the association between rs1799762 PAI-1 gene polymorphism and the risk of RPL.

METHODS

A systematic search for studies that assessed the association between PAI-1 4G/5G polymorphism and RPL risk published in search sources, PubMed/Medline, ISI Web of Knowledge, Scopus, and Google Scholar till January 2024 was conducted.

RESULTS

There were 23 case-control studies in total, with a high degree of statistical heterogeneity among them which indicated the need for subgroup analysis. We found a significant positive association between the risk of RPL and 4G/4G PAI-1 (OR: 2.57; 95% CI: 1.69-3.90), likewise 4G/5G (OR: 2/02 95% CI: 1.39-2.92) and mixed genotype (4G/4G+4G/5G) (OR: 2.31 95% CI: 1.81-2.93). Considering the ethnicity, the 4G/4G polymorphism is significantly associated with Asian descent (OR: 2.10; CI: 1.65-2.69) while the strong association (OR: 6.47; CI: 3.23-12.97) observed in the Greater Middle East descent is not statistically significant (P=0.16). PAI-1 4G/5G polymorphism association with RPL was only significant in Greater Middle East descent (OR: 2.93; CI: 2.41-3.56), and mixed genotype was significantly associated with RPL in Asian (OR: 2.37; CI: 1.55-3.61), Greater Middle East (OR: 3.01; CI: 2.16-4.19), and European populations (OR: 1.38; CI: 0.91-2.10). The association between RPL and PAI-1 4G/4G was significant for RPLs both under 12 weeks (OR: 1.82; 95% CI: 1.34-2.47), and under 24 weeks (OR: 1.46; 95% CI: 1.11-1.92), while considering heterozygote form the association was only significant for RPLs under 24 weeks (OR: 1.91; 95% CI: 1.58-2.31). Regarding the mixed genotype, there is a significant positive association between PAI-1 and RPL for RPLs under 12 weeks (OR: 2.09; 95% CI: 1.49-2.93), and under 24 weeks (OR: 2.10; 95% CI: 1.52-2.92).

CONCLUSIONS

Our findings indicate a significant association between the rs1799762 PAI-1 polymorphism and the risk of RPL.

Frequency of Gene Polymorphisms in Admixed Venezuelan Women with Recurrent Pregnancy Loss: Microsomal Epoxy Hydroxylase (rs1051740) and Enos (rs1799983)

Recurrent pregnancy loss (RPL) affects around 2% of women of reproductive age. Primary RPL is defined by ≥2 pregnancy losses and no normal birth delivery. In secondary RPL, the losses are after a normal pregnancy and delivery. Most cases have no clear aetiology, although primary cases are the most complex. Several gene single nucleotide polymorphisms (SNPs) have been associated with RPL. The frequency of some SNPs is increased in women suffering from RLP from Asian or Caucasian races; however, in admixed populations, the information on possible genetic links is scarce and contradictory. This study aimed to assess the frequency of two SNPs present in two different enzymes involved in medical conditions observed during pregnancy. It is a case-control study. Microsomal epoxy hydrolase (mEPH) is involved in detoxifying xenobiotics, is present in the ovaries, and is hormonally regulated. The endothelial nitric oxide synthase (NOS3) that forms nitric is involved in vascular tone. Two SNPs, rs1051740 (mEPH) and rs1799983 (NOS3), were assessed. The study included 50 controls and 63 primary RPL patients. The frequency of mutated alleles in both SNPs was significantly higher in patients (p < 0.05). Double-mutated homozygotes were encountered only in RPL patients (p < 0.05). Genetic polymorphisms rs1051740 and rs1799983 may be involved in primary RPL in the Venezuelan admix population. Genetic studies could provide crucial information on the aetiology of primary RPL.

Association of Y chromosome AZF region microdeletions with recurrent miscarriage in Iranian couples: A case-control study

BACKGROUND

Recent studies have linked recurrent pregnancy loss (RPL) to abnormalities in the sperm genome, specifically microdeletions in the azoospermia factor (AZF) region. This study investigated the potential association between Y chromosome microdeletions in the AZF region and RPL in Iranian couples.

METHODS

The research presents a case-control study of 240 men: 120 whose partners experienced recurrent miscarriage, and 120 who had successful pregnancies without history of miscarriage. The study used semen parameters, hormone analyses, and microdeletion analysis via multiplex PCR and the YChromStrip kit. Thus, the sequence-tagged site (STS) markers of AZFa (sY84, sY86), AZFb (sY127, sY134), and AZFc (sY254, sY255) regions were examined.

RESULTS

The variations in semen parameters and sex hormone levels between cases and controls are suggest impaired testicular function in men whose partners had recurrent miscarriages (p < 0.05). Furthermore, the study revealed a negative correlation between sperm count and follicle-stimulating hormone (FSH) level, and a positive one between sperm motility and testosterone concentration. There were no microdeletions in the control group, while the RPL group showed 20 deletions in AZFb (sY134) (16.66%) and 10 deletions each in AZFb (sY127) (8.33%) and AZFc (sY254) (8.33%).

CONCLUSION

Microdeletions in sY134 (AZFb) were significantly associated with RPL in Iranian men (p = 0.03). AZF microdeletion screening in couples with RPL can provide valuable information for ethnical genetic counseling and management of recurrent miscarriage. Further studies on larger populations or across various ethnic groups, conclusions and the inclusion of other factors like epigenetic changes explain the role of AZF microdeletions in RPL.

HNRNPC mediated m6A methylation of 5-methyltetrahydrofolate-homocysteine methyltransferase and involved in the occurrence of RSA

N6-methyladenosine methylated modification has been shown to play roles in recurrent spontaneous abortion. We aimed to explore role of heterogeneous nuclear ribonucleoprotein C in the occurrence of recurrent spontaneous abortion. We collected embryonic villous tissues from 3 patients with recurrent spontaneous abortion (RSA group) and 3 normal control pregnancy patients. Methylated RNA immunoprecipitation sequencing, RNA sequencing, methylated RNA immunoprecipitation quantitative PCR were conducted to detect the differentially expressed m6A methylation modification gene and regulatory gene in patients with recurrent spontaneous abortion. Methylated RNA immunoprecipitation sequencing and RNA sequencing results showed that the mRNA expression level of heterogeneous nuclear ribonucleoprotein C significantly decreased in RSA group and mRNA expression level of 5-methyltetrahydrofolate-homocysteine methyltransferase increased. Real-time quantitative PCR confirmed the differential expression of heterogeneous nuclear ribonucleoprotein C and 5-methyltetrahydrofolate-homocysteine methyltransferase. Methylated RNA immunoprecipitation quantitative PCR result showed that mRNA m6A modification level of 5-methyltetrahydrofolate-homocysteine methyltransferase decreased in RSA group. The results of western blotting, real-time quantitative PCR, immunofluorescence, matrigel invasion and wound healing assays indicated that heterogeneous nuclear ribonucleoprotein C might regulate the expression of 5-methyltetrahydrofolate-homocysteine methyltransferase by mediating m6A modification, thereby reducing the proliferation and migration of trophoblast cell line, ultimately leading to the occurrence of recurrent spontaneous abortion.

Platelet Glycoprotein Receptor Ia-C807T and IIIa-PlA1/PlA2 Genetic Polymorphisms Are Associated With Enhanced Platelet Function in Women With Recurrent Miscarriages

INTRODUCTION

Thrombophilic genetic polymorphisms of the platelet glycoproteins Ia (GpIa) and IIIa (GpIIIa) have been associated with an increased risk of recurrent miscarriages. The aim of this study was to investigate the association of genetic polymorphisms GpIa-C807T and GpIIIa-T1565C-PlA1/PlA2 with platelet function in women with unexplained spontaneous recurrent miscarriages.

METHODS

This cross-sectional study comprised 196 unrelated nulliparous Greek women with a history of unexplained recurrent miscarriages. Patients were genotyped for the presence of the GpIa-C807T (rs1126643) and GpIIIa-T1565C-PlA1/PlA2 (rs5918) genetic polymorphisms by pyrosequencing, and the collagen/epinephrine closure time (COL/EPI CT) of the subjects was assessed using the platelet function analyzer (PFA)-100.

RESULTS

 In the total population of women with recurrent miscarriages, the COL/EPI CT ranged from 70 to 160 seconds (median: 122 seconds, interquartile range (IQR): 102.3-138 seconds). In comparison with the double homozygotes CC/PlA1PlA1 that had the most prolonged CT (mean: 131.9 ± 17.5 seconds), the COL/EPI CT was statistically significantly shorter for the GpIa-807T single carriers (mean: 120.3 ± 20.9 seconds) (p=0.011) (absolute difference: 11.6 seconds, 95% confidence interval (CI): 21.2 to -2.0 seconds; relative difference: -9%, 95% CI: -16% to -2%), and the GpIIIa-PlA2 single carriers also displayed a trend for shorter COL/EPI CT (mean: 121.3 ± 23.7 seconds) (p=0.141) (absolute difference: -10.6 seconds, relative difference: -8%), whereas the combined carriers of the GpIa-807T and the GpIIIa-PlA2 alleles exhibited the shortest COL/EPI CT (mean: 104.1 ± 19.7 seconds) (absolute difference: -27.7 seconds, 95% CI: -39.1 to -16.3 seconds; relative difference: -21%, 95% CI: -30% to -12%) (p<0.001). In comparing genotype frequencies in the lower half with those in the upper half of the COL/EPI CT range, the GpIa-807T and the GpIIIa-PlA2 single carriers were associated with higher odds of COL/EPI CT < 122 seconds (odds ratio (OR)=3.4, 95% CI: 1.5 to 7.5, p=0.002, and OR=2.6, 95% CI: 1.0 to 7.2, p=0.053, respectively). The association was strongest for the combined carriers with OR of 15.0 (95% CI: 5.2 to 43.2, p<0.001) for COL/EPI CT below the median and OR of 35.5 (95% CI: 4.4 to 284.5, p<0.001) for COL/EPI CT < 100 seconds.

CONCLUSION

The GpIa-C807T and GpIIIa-PlA1/PlA2 polymorphisms and more pronouncedly the combined carriers of the risk variants are associated with enhanced platelet reactivity expressed via shorter COL/EPI CT. These findings provide further evidence for the role of platelet-associated genetic thrombophilia in the pathogenesis of recurrent miscarriages and promote the analysis of platelet function as a diagnostic tool in the evaluation of this disorder.

Opposing impacts of HLA-G haplotypes PROMO-G010104-UTR-3 and PROMO-G010101b/c-UTR-4 on risk of recurrent implantation failure

RESEARCH QUESTION

The human leukocyte antigen (HLA) class Ib molecules HLA-F and HLA-G are implicated in pregnancy success, but how do HLA-G and HLA-F genetic polymorphisms impact recurrent implantation failure (RIF)?

DESIGN

Prospective cohort study at a fertility clinic including a cohort of 84 women experiencing RIF and 35 IVF controls to assess the influence of HLA-G haplotypes and diplotypes and HLA-F single nucleotide polymorphisms (SNP) on RIF.

RESULTS

Over-representation trends for HLA-F SNP genotypes rs1362126, rs2523405 and rs2523393, previously linked with a short time-to-pregnancy, were detected in female control groups compared with RIF patients with no identified pathology linked to infertility. The HLA-G promoter haplotype PROMO-G010101b/c linked with the HLA-G 3'-untranslated region (3'UTR) haplotype UTR-4, which previously has been associated with positive IVF outcome and pregnancy success, was less frequent in the RIF group. For RIF patients carrying the UTR-4 haplotype, the odds ratio (OR) was 0.27 (95% CI 0.12-0.66; P = 0.0044, Pc = 0.026). The HLA-G PROMO-G010104-UTR-3 haplotype was associated with an increased risk of RIF. For RIF patients carrying the UTR-3 haplotype, the OR was 5.86 (95% CI 1.52-26.23; P = 0.0115, Pc = 0.069).

CONCLUSIONS

These results show that specific HLA-G haplotypes based on the promoter region and the 3'UTR are either associated with an increased risk of reduced fertility, including the manifestation of RIF, and lower chance of achieving pregnancy, or with a reduced risk of experiencing RIF.

Estimation on risk of spontaneous abortions by genomic disorders from a meta-analysis of microarray results on large case series of pregnancy losses

A meta-analysis on seven large case series (>1000 cases) of chromosome microarray analysis (CMA) on products of conceptions (POC) evaluated the diagnostic yields of genomic disorders and syndromic pathogenic copy number variants (pCNVs) from a collection of 35,130 POC cases. CMA detected chromosomal abnormalities and pCNVs in approximately 50% and 2.5% of cases, respectively. The genomic disorders and syndromic pCNVs accounted for 31% of the detected pCNVs, and their incidences in POC ranged from 1/750 to 1/12,000. The newborn incidences of these genomic disorders and syndromic pCNVs were estimated in a range of 1/4000 to 1/50,000 live births from population genetic studies and diagnostic yields of a large case series of 32,587 pediatric patients. The risk of spontaneous abortion (SAB) for DiGeorge syndrome (DGS), Wolf-Hirschhorn syndrome (WHS), and William-Beuren syndrome (WBS) was 42%, 33%, and 21%, respectively. The estimated overall risk of SAB for major genomic disorders and syndromic pCNVs was approximately 38%, which was significantly lower than the 94% overall risk of SAB for chromosomal abnormalities. Further classification on levels of risk of SAB to high (>75%), intermediate (51%-75%), and low (26%-50%) for known chromosomal abnormalities, genomic disorders, and syndromic pCNVs could provide evidence-based interpretation in prenatal diagnosis and genetic counseling.

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.

Understanding recurrent pregnancy loss: recent advances on its etiology, clinical diagnosis, and management

Recurrent pregnancy loss (RPL) has become an important reproductive health issue worldwide. RPL affects about 2%-3% of reproductive-aged women, and makes serious threats to women's physical and mental health. However, the etiology of approximately 50% of RPL cases remains unknown (unexplained RPL), which poses a big challenge for clinical management of these patients. RPL has been widely regarded as a complex disease where its etiology has been attributed to numerous factors. Heretofore, various risk factors for RPL have been identified, such as maternal ages, genetic factors, anatomical structural abnormalities, endocrine dysfunction, prethrombotic state, immunological factors, and infection. More importantly, development and applications of next generation sequencing technology have significantly expanded opportunities to discover chromosomal aberrations and single gene variants responsible for RPL, which provides new insight into its pathogenic mechanisms. Furthermore, based upon patients' diagnostic evaluation and etiologic diagnosis, specific therapeutic recommendations have been established. This review will highlight current understanding and recent advances on RPL, with a special focus on the immunological and genetic etiologies, clinical diagnosis and therapeutic management.

Association of parental HLA-G polymorphisms with soluble HLA-G expressions and their roles on recurrent implantation failure: A systematic review and meta-analysis

Introduction

HLA-G plays a central role in immune tolerance at the maternal-fetal interface. The HLA-G gene is characterized by low allelic polymorphism and restricted tissue expression compared with classical HLA genes. HLA-G polymorphism is associated with HLA-G expression and linked to pregnancy complications. However, the association of parental HLA-G polymorphisms with soluble HLA-G (sHLA-G) expression and their roles in recurrent implantation failure (RIF) is unclear. The study aims to systematically review the association of HLA-G polymorphisms with RIF, the association of sHLA-G expression with RIF, and the association of HLA-G polymorphisms with sHLA-G expressions in patients attending in-vitro fertilization (IVF) treatment.

Methods

Studies that evaluated the association of HLA-G polymorphisms with RIF, the association between sHLA-G expression with RIF, and the association between HLA-G polymorphisms with sHLA-G expressions in patients attending IVF treatment were included. Meta-analysis was performed by random-effect models. Sensitivity analysis was performed by excluding one study each time. Subgroup analysis was performed based on ethnicity.

Results

HLA-G 14bp ins variant is associated with a lower expression of sHLA-G in seminal or blood plasma of couples attending IVF treatment. The maternal HLA-G*010101 and paternal HLA-G*010102 alleles are associated with RIF risk compared to other alleles. However, single maternal HLA-G 14bp ins/del polymorphism, HLA-G -725 C>G/T polymorphism, or circulating sHLA-G concentration was not significantly associated with RIF in the general population. HLA-G 14bp ins/ins homozygous genotype or ins variant was associated with a higher risk of RIF in the Caucasian population.

Discussion

Specific HLA-G alleles or HLA-G polymorphisms are associated with sHLA-G expression in couples attending IVF treatment. Several HLA-G polymorphisms may be related to RIF, considering different ethnic backgrounds. A combined genetic effect should be considered in future studies to confirm the association of HLA-G polymorphisms and sHLA-G expressions in relation to RIF.

Association between TP53 Arg72Pro variant and recurrent pregnancy loss in the Greek population

OBJECTIVES

The present case-control study investigates whether TP53 Arg72Pro variant (rs1042522) serves as a risk factor for recurrent pregnancy loss (RPL) in Greek women.

METHODS

The study group consisted of 100 patients with at least two miscarriages of unexplained etiology, before the 24th week of gestation. The control group included 106 women with no pregnancy loss history. DNA was extracted and genotyped using specific primers for PCR amplification of the Arg72 and Pro72 alleles. Sanger sequencing was used for the discrimination between heterozygotes and homozygotes for Arg72Pro variant.

RESULTS

This is the first study demonstrating the statistically significant higher frequency of TP53 Arg72Pro variant in Greek RPL women compared to controls (38% vs. 6.6%; OR=8.6682, 95% CI: 3.6446-20.6160; p<0.0001). GC genotype (Arg/Pro) and CC genotype (Pro/Pro) were statistically more common in RPL patients than in controls (16% vs. 1.9%; p=0.0027, and 22 vs. 4.7%; p=0.0008, respectively). C allele frequency was statistically significant higher in RPL group than in controls (30.0 vs. 5.7%; p<0.0001). According to the inheritance mode analysis, the model that best fit the data was the dominant model (OR=8.67, 95% CI=3.64-20.62; p<0.0001).

CONCLUSIONS

The is the first study disclosing strong evidence that TP53 rs1042522 is significantly associated with a higher risk for recurrent pregnancy loss in Greek women following a dominant model, thus, serving as a genetic marker for identifying women at increased risk of recurrent miscarriages.

Endometrial HLA-F expression is influenced by genotypes and correlates differently with immune cell infiltration in IVF and recurrent implantation failure patients

STUDY QUESTION

Is human leukocyte antigen (HLA)-F protein expressed in mid-secretory endometrium, and are its expression levels influenced by HLA-F gene polymorphisms and correlated with the abundance of uterine natural killer (uNK) cells and anti-inflammatory M2 macrophages?

SUMMARY ANSWER

HLA-F protein is expressed in mid-secretory endometrium, and levels are correlated with immune cell infiltration, plasma progesterone concentrations and HLA-F single-nucleotide polymorphisms (SNPs), however, women experiencing recurrent implantation failure (RIF) show differences when compared to women attending their first IVF treatment.

WHAT IS KNOWN ALREADY

The immunomodulatory HLA class Ib molecules HLA-G and HLA-F are expressed on the extravillous trophoblast cells and interact with receptors on maternal immune cells. Little is known regarding HLA-F expression in endometrial stroma and HLA-F function; furthermore, HLA-F and HLA-G SNP genotypes and haplotypes have been correlated with differences in time-to-pregnancy.

STUDY DESIGN, SIZE, DURATION

Primary endometrial stromal cell (ESC) cultures (n = 5) were established from endometrial biopsies from women attending IVF treatment at a fertility clinic. Basic HLA-F and HLA-G protein expression by the ESCs were investigated. A prospective controlled cohort study was performed including 85 women with a history of RIF and 36 control women beginning their first fertility treatment and with no history of RIF. In some analyses, the RIF group was divided into unknown cause, male infertility, female infertility, and both female and male infertility. Endometrial biopsies and blood samples were obtained the day equivalent to embryo transfer in a hormone-substituted cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS

HLA protein expression by ESCs was characterized using flow cytometry and western blot. In the cohort study, the specific immune markers HLA-F and HLA-G, CD56 and CD16 (NK cells), CD163 (M2 macrophages), FOXP3 (regulatory T cells) and CD138 (plasma cells) were analysed by immunohistochemistry and a digital image analysis system in endometrial biopsies. Endometrial receptivity was assessed by an endometrial receptivity array test (the ERA® test). Endometrial biopsies were examined according to modified Noyes' criteria. SNPs at the HLA-F gene and HLA-G haplotypes were determined.

MAIN RESULTS AND THE ROLE OF CHANCE

HLA-F protein is expressed in the endometrium at the time of implantation. Furthermore, the HLA-F protein levels were different according to the womeńs HLA-F SNP genotypes and diplotypes, which have previously been correlated with differences in time-to-pregnancy. Endometrial HLA-F was positively correlated with anti-inflammatory CD163+ M2 macrophage infiltration and CD56+ uNK cell abundance for the entire cohort. However, this was not the case for CD56+ in the female infertility RIF subgroup. HLA-F levels in the endometrial stroma were negatively correlated with plasma progesterone concentrations in the RIF subgroup with known female infertility. Conversely, HLA-F and progesterone were positively correlated in the RIF subgroup with infertility of the male partner and no infertility diagnosis of the woman indicating interconnections between progesterone, HLA-F and immune cell infiltration. Glandular sHLA-G expression was also positively correlated with uNK cell abundance in the RIF subgroup with no female infertility but negatively correlated in the RIF subgroup with a female infertility diagnosis.

LARGE SCALE DATA

Immunohistochemistry analyses of endometrial biopsies and DNA sequencing of HLA genes. Data will be shared upon reasonable request to the corresponding author.

LIMITATIONS, REASONS FOR CAUTION

The control group of women attending their first IVF treatment had an anticipated good prognosis but was not proven fertile. A significant age difference between the RIF group and the IVF group reflects the longer treatment period for women with a history of RIF. The standardization of hormonal endometrial preparation, which allowed consistent timing of endometrial and blood sampling, might be a strength because a more uniform hormonal background may more clearly show an influence on the immune marker profile and HLA class Ib levels in the endometrium by other factors, for example genetic polymorphisms. However, the immune marker profile might be different during a normal cycle.

WIDER IMPLICATIONS OF THE FINDINGS

The findings further highlight the importance of HLA-F and HLA-G at the implantation site and in early pregnancy for pregnancy success. Diagnostic measures and modulation of the complex interactions between HLA class Ib molecules, maternal immune cells and hormonal factors may have potential to improve fertility treatment.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Region Zealand Health Sciences Research Foundation and the Zealand University Hospital through the ReproHealth Research Consortium ZUH. The authors declared there are no conflicts of interest.

Evaluating the Association Between Genetic Polymorphisms Related to Homocysteine Metabolism and Unexplained Recurrent Pregnancy Loss in Women

Objective

To investigate the relationship between unexplained recurrent pregnancy loss (URPL) and polymorphisms of homocysteine metabolism-related genes in women.

Materials and Methods

A case–control study included 90 women with two or more consecutive unexplained pregnancy losses and 92 controlled women without miscarriage history; the female participants were in the age category of 18–35 years. The high-resolution melting technique was used to detect the single-nucleotide variants related to homocysteine metabolism disorder, namely MTHFR C677T, MTHFR A1298C, MTR A2756G, and MTRR A66G polymorphism.

Results

The MTHFR C677T polymorphism had significantly correlation with URPL. Indeed, the frequency of the677T allele and genotypes (677CT, 677TT) in the URPL group was significantly higher than that in the control group (p < 0.05). However, the allele, as well as genotype distribution of MTHFR A1298C, MTR A2756G, and MTRR A66G polymorphisms showed no significant difference (p > 0.05). MTHFR 677CT-1298AC genotype combination led to a 9.0-fold increased risk of URPL (OR 9.0; 95% CI, 2.25–35.99; p = 0.001), while the risk increased 10.0-fold (OR 10.0; 95% CI, 1.8–55.53; p = 0.008) when participants had more than the 3 variant loci.

Conclusion

The MTHFR C677T polymorphism was a risk factor for URPL, and determining the MTHFR C677T polymorphism had a potential prediction of URPL risk. Moreover, the MTHFR C677T and MTHFR A1298C joint mutants might have a synergistic effect on URPL. Conversely, there is a lack of evidence suggesting the URPL risk of MTHFR A1298C, MTR A2756G, and MTRR A66G polymorphisms.

MTR, MTRR and CBS Gene Polymorphisms in Recurrent Miscarriages: A Case Control Study from North India

Background:

According to various epidemiological studies, the aetiology of recurrent miscarriages (RMs) is multifactorial. The goal of this study is to learn more about the link between genetic polymorphisms and RM.

Aim:

To evaluate the association of 5-Methytetrahydrofolate-Homocysteine Methyltransferase (MTR) A2756G, 5-Methytetrahydrofolate-Homocysteine Methyltransferase Reductase (MTRR) A66G and cystathionine beta-synthase (CBS) 844INS68 genetic polymorphisms with RM and also to understand the combined effect of the selected genotypes.

Study Setting and Design:

This was a hospital-based, case–control, observational study.

Materials and Methods:

A total of 516 participants were recruited in the present study, of which 200 RM cases and 258 controls were included in the present study. Fasting blood sample (~5ml) was drawn from all the participants and were screened for genetic polymorphisms of MTR A2756G, MTRR A66G and CBS 844INS68.

Statistical Analysis:

The frequency, odd's ratio and Hardy-Weinberg equilibrium were evaluated. SPSS (version 21.0) was used for the data analysis.

Results:

MTR A2756G genetic polymorphism was not associated with the risk of RM. The ancestral allele of MTRR A66G and the mutant allele of CBS 844INS68 was causing an increased risk of more than two folds for RM. CBS 844INS68 in combination with MTR A2756G was found to pose an increased risk of more than two folds for RM.

Conclusion:

Genetic polymorphisms particularly MTRR A66G and CBS 844INS68 seems to be elevating the risk and hence making women susceptible for RM.

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.

The Investigation of Metabonomic Pathways of Serum of Iranian Women with Recurrent Miscarriage Using 1H NMR

Purpose

Recurrent miscarriage applies to pregnancy loss expulsion of the fetus within the first 24 weeks of pregnancy. This study is aimed at comparatively investigating the sera of women with RM with those who have no record of miscarriages to identify if there were any metabolite and metabolic pathway differences using ¹H NMR spectroscopy.

Methods

Serum samples were collected from women with RM (n = 30) and those who had no records of RM (n = 30) to obtain metabolomics information. ¹H NMR spectroscopy was carried out on the samples using Carr Purcell Meiboom Gill spin echo; also, Partial Least Squares Discriminant Analysis was performed in MATLAB software using the ProMetab program to obtain the classifying chemical shifts; the metabolites were identified by using the Human Metabolome Database (HMDB) in both the experimental and control groups. The pathway analysis option of the Metaboanalyst.ca website was used to identify the changed metabolic pathways.

Results

The results of the study revealed that 14 metabolites were different in the patients with RM. Moreover, the pathway analysis showed that taurine and hypotaurine metabolism along with phenylalanine, tyrosine, and tryptophan biosynthesis was significantly different in patients with RM.

Conclusion

The present study proposes that any alteration in the above metabolic pathways might lead to metabolic dysfunctions which may result in a higher probability of RM.

The lncRNA ANRIL Gene rs2151280 GG Genotype is Associated with Increased Susceptibility to Recurrent Miscarriage in a Southern Chinese Population

Background

Genetic factors may play an important role in susceptibility to recurrent miscarriage. Some cardiovascular disease-related candidate genes have been shown to be associated with recurrent miscarriage. Long noncoding RNA ANRIL has been confirmed to be associated with susceptibility to various diseases, such as cardiovascular disease. However, it remains unclear whether the ANRIL gene polymorphism is related to recurrent miscarriage susceptibility.

Methods

Three ANRIL gene polymorphisms (rs2151280, rs1063192 and rs564398) were genotyped in 819 controls and 610 recurrent miscarriage patients through TaqMan real-time polymerase chain reaction. The odds ratios and 95% confidence intervals (CIs) were used to assess the strength of each association.

Results

Our results showed that the ANRIL rs2151280 GG genotype was associated with increased susceptibility to recurrent miscarriage (GG vs AA: adjusted OR=1.527, 95% CI=1.051–2.218, p=0.0262; GG vs AG/AA adjusted OR=1.460, 95% CI=1.021–2.089, p=0.0381). By combining the analysis of the risk genotypes in the three SNPs, we found that individuals with 2–3 risk genotypes had a significantly increased risk of recurrent miscarriage compared with those with a 0–1 risk genotype (adjusted OR=1.728, 95% CI=1.112–2.683, p=0.0149). This risk was more significant in subgroups of women less than 35–40 years of age and women with 2–3 miscarriages.

Conclusion

These results suggested that a specific SNP in the ANRIL gene may be associated with increased susceptibility to recurrent miscarriage in a southern Chinese population.

Cis-Segregation of c.1171C>T Stop Codon (p.R391*) in SERPINC1 Gene and c.1691G>A Transition (p.R506Q) in F5 Gene and Selected GWAS Multilocus Approach in Inherited Thrombophilia

Inherited thrombophilia (e.g., venous thromboembolism, VTE) is due to rare loss-of-function mutations in anticoagulant factors genes (i.e., SERPINC1, PROC, PROS1), common gain-of-function mutations in procoagulant factors genes (i.e., F5, F2), and acquired risk conditions. Genome Wide Association Studies (GWAS) recently recognized several genes associated with VTE though gene defects may unpredictably remain asymptomatic, so calculating the individual genetic predisposition is a challenging task. We investigated a large family with severe, recurrent, early-onset VTE in which two sisters experienced VTE during pregnancies characterized by a perinatal in-utero thrombosis in the newborn and a life-saving pregnancy-interruption because of massive VTE, respectively. A nonsense mutation (CGA > TGA) generating a premature stop-codon (c.1171C>T; p.R391*) in the exon 6 of SERPINC1 gene (1q25.1) causing Antithrombin (AT) deficiency and the common missense mutation (c.1691G>A; p.R506Q) in the exon 10 of F5 gene (1q24.2) (i.e., FV Leiden; rs6025) were coinherited in all the symptomatic members investigated suspecting a cis-segregation further confirmed by STR-linkage-analyses [i.e., SERPINC1 IVS5 (ATT)_5–18, F5 IVS2 (AT)_6–33 and F5 IVS11 (GT)_12–16] and SERPINC1 intragenic variants (i.e., rs5878 and rs677). A multilocus investigation of blood-coagulation balance genes detected the coexistence of FV Leiden (rs6025) in trans with FV HR2-haplotype (p.H1299R; rs1800595) in the aborted fetus, and F11 rs2289252, F12 rs1801020, F13A1 rs5985, and KNG1 rs710446 in the newborn and other members. Common selected gene variants may strongly synergize with less common mutations tuning potential life-threatening conditions when combined with rare severest mutations. Merging classic and newly GWAS-identified gene markers in at risk families is mandatory for VTE risk estimation in the clinical practice, avoiding partial risk score evaluation in unrecognized at risk patients.

A meta-analysis of the association of the ACE I/D and PAI-1 4G/5G polymorphisms with recurrent pregnancy loss in Iranian women: Are the investigations adequate?

The associations of ACE I/D and PAI-1 4G/5G polymorphisms with recurrent pregnancy loss (RPL) in Iranian women have yielded controversial results. Thus, we conducted a meta-analysis to obtain more certain results. A comprehensive literature search was performed in the PubMed, Web of Sciences, Scopus, MedRxiv, SID, and CNKI databases up to January 1st, 2021, using the appropriate terms. All case-control studies were included. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to estimate the strength of associations. A total of 14 studies including eight studies with 783 patients and 761 healthy subjects on ACE I/D and six studies with 1.155 patients and 699 healthy subjects on PAI-1 4G/5G were included. Combined data revealed that ACE I/D polymorphism was significantly associated with RPL risk in Iranian women under three models i.e., allele [OR=0.744, 95% CI: (0.640-0.864); p≤0.001], dominant [OR=0.774, 95% CI: (0.601-0.996); p=0.047], and recessive [OR=0.767, 95% CI: (0.611-0.963); p=0.022]. Moreover, the pooled data showed a significant association between the PAI-1 4G/5G polymorphism and RPL risk under all five models i.e., allele [OR=2.352, 95% CI: (1.623-3.408); p≤0.001], heterozygote [OR=8.364, 95% CI: (4.744-14.756); p≤0.001), homozygote [OR=2.192, 95% CI: (1.093-4.394); p=0.027), dominant [OR=2.354, 95% CI: (1.309-4.235); p=0.004], and recessive [OR=5.208, 95% CI: (3.005-9.025); p≤0.001]. Stratification analysis revealed that these polymorphisms were associated with RPL risk by the number of miscarriages. Our pooled data indicated that ACE I/D and PAI-1 4G/5G polymorphisms were significantly associated with an increased risk of RPL in Iranian women. These significant findings showed that the investigation might be adequate for ACE I/D and PAI-1 4G/5G polymorphisms in the Iranian population.

Folate metabolizing gene polymorphisms and genetic vulnerability to preterm birth in Korean women

BACKGROUND

The folate metabolism that converts homocysteine to methionine is closely related to the accumulation of homocysteine. Increased homocysteine levels lead to an impaired antithrombotic function of the vascular endothelium and uterine-placental circulation, resulting in abnormal pregnancy outcomes. Previous studies have reported that gene polymorphisms in folate metabolism are associated with the development of preterm birth (PTB) in various populations.

OBJECTIVE

we performed a case-control study to evaluate the association between five polymorphisms in folate metabolic genes (MTHFR, MTR, MTRR, TCN2) and PTB.

METHODS

In this study, a total of 254 subjects were analyzed (111 patients with PTB and 143 women at ≥ 38 weeks of gestation). Genotype and allele frequency differences between patients and control groups and the Hardy-Weinberg equilibrium were assessed using a Chi-square test. For evaluation indicators, odds ratios (ORs) of 95% confidence intervals (CI) were estimated. In addition, we analyzed the combined genotype frequencies of SNPs of folate-metabolizing genes to measure gene-gene interactions for PTB.

RESULTS

Our results showed that the MTR rs1805087 GG (p = 0.031), and TCN2 rs1801198 CG genotype (OR 0.53, 95% CI 0.288-0.980, p = 0.042) were significantly associated with PTB. The MTHFR rs4846049 AA showed a marginal trend toward significance (OR 0.15, 95% CI 0.018-1.205, p = 0.041). In particular, the combined genotypes, including MTHFR rs1537514 CC-MTRR rs1801394 GG, MTHFR rs1537514 CC-TCN2 rs1801198 CG, and MTR rs1805087 AA-TCN2 rs1801198 CG, have significant interactions with PTB (OR 0.49, 95% CI 0.248-0.992, p < 0.05).

CONCLUSION

The polymorphisms of folate metabolic genes may have a genetic association with the development of PTB in Korean women. A larger sample set and functional studies are required to further elucidate our findings.

Association of homocysteine with IVF/ICSI outcomes stratified by MTHFR C677T polymorphisms: a prospective cohort study

RESEARCH QUESTION

What is the association between homocysteine (Hcy) and IVF/intracytoplasmic sperm injection (ICSI) outcomes, stratified by methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms?

DESIGN

This prospective cohort study recruited 1011 infertile women undergoing IVF/ICSI treatment for the first time at the International Peace Maternity and Child Health Hospital between June 2015 and March 2018.

RESULTS

The concentration of total serum Hcy was significantly negatively associated with clinical pregnancy and implantation rate. When adjusted for maternal and paternal age and educational level, maternal body mass index, and FSH and oestradiol concentrations, logistic regression analysis showed that women with higher Hcy had a higher risk of unsuccessful pregnancy. After stratification by MTHFR C677T polymorphisms and adjustment for confounding factors, a higher risk of unsuccessful pregnancy and a significantly lower implantation rate only existed in women with higher Hcy concentration in the MTHFR C677T TT genotype. There was no significant association between Hcy concentrations and other ovarian stimulation outcomes (oocytes retrieved, metaphase II stage oocytes, fertilization rate, cleavage rate, high-quality embryo rate) or neonatal outcomes (preterm birth, gestational age at delivery, Caesarean section, birthweight, small for gestational age, large for gestational age or birth defects).

CONCLUSIONS

Hcy is highly negatively associated with clinical pregnancy and implantation rate during the first IVF/ICSI cycle, especially in women carrying the MTHFR C677T TT genotype. Other factors with impacts on reproductive outcomes, such as stage of embryo transferred, other factors involved in folate metabolism, preimplantation genetic testing, etc., should be taken into account in further research.

Association of Tumor Necrosis Factor-α -308G>A, -238G>A and -376G>A polymorphisms with recurrent pregnancy loss risk in the Greek population

Background

Promoter region SNPs in TNF-α have been studied in association with Recurrent Pregnancy Loss (RPL) occurrence in various populations. Among them, −238G > A, −308G > A and − 376G > A have been frequently investigated for their potential role in recurrent abortions. The aim of the present study is to evaluate the correlation among TNF-α 238, TNF-α 308 and TNF-α 376 polymorphisms and recurrent pregnancy loss risk in Greek women.

Methods

This study included 94 Caucasian women with at least two miscarriages of unexplained aetiology, before the 20th week of gestation. The control group consisted of 89 Caucasian women of proven fertility, with no history of pregnancy loss. DNA samples were subjected to PCR amplification using specific primers. Sanger sequencing was applied to investigate the presence of TNF-α 238, TNF-α 308, TNF-α 376 polymorphisms in all samples.

Results

The TNF-α 238 and TNF-α 308 variants were both detected in RPL and control groups (7.45% vs 4.49 and 45.16% vs 36.73%, respectively), but with no statistically significant association (p-value 0.396 and 0.374, respectively). The TNF-α 376 variant was not detected at all in both control and RPL groups. When TNF-α 238 and TNF-α 308 genotypes were combined no association with RPL was detected (p-value = 0.694). In subgroup analysis by parity, RPL patients carrying the A allele reported less previous births.

Conclusions

This is the first study demonstrating TNF-α 238 and TNF-α 308 gene expression and the absence of TNF-α 376 variant in Greek women with RPL. However, no association emerged between each polymorphism studied and the occurrence of recurrent pregnancy loss. Accordingly, TNF-α -308G > A, −238G > A and -376G > A variants are not considered genetic markers for identifying women at increased risk of recurrent pregnancy loss in the Greek population.

Combinations of fibrinolytic gene polymorphisms (plasminogen activator inhibitor type 1 4G/5G, factor XIII Val34Leu and angiotensin-converting enzyme I/D) in women with idiopathic infertility

During normal pregnancy depressed fibrinolytic system is caused by changes in many factors, which could be influenced by different gene polymorphisms. The aim of this study was to investigate the combination of fibrinolysis-related gene polymorphisms in women with idiopathic infertility. We genotype polymorphisms 4G/5G in plasminogen activator inhibitor type 1 (PAI-1), Val34Leu in factor XIII (FXIII) and I/D in angiotensin-converting enzyme (ACE) gene. The patients group consisted of 83 females with idiopathic infertility, while the control group included 121 females with at least one born child. The alleles and genotypes distributions showed no significant differences between analyzed groups. Although higher frequency of PAI-1 5G5G genotype in patients did not reach statistical significance, 5G5G genotype of PAI-1 in combination with ValVal genotype of FXIII leads to higher risk for infertility (P < 0.05). In addition, when we added ACE I/D polymorphism in analysis, the 4G in PAI-1 and D allele in ACE, showed protective effect in combination with FXIII polymorphism (P < 0.05). The finding that combined homozygosity of 5G of PAI-1, commonly associated with greater fibrinolytic activity and bleeding tendency, in combination with Val genotype of FXIII impose a risk for female idiopathic infertility. The protective effect of alleles 4G (PAI-1) and D (ACE) suggest that different combinations of polymorphisms influencing fibrinolysis could lead to better established hemostatic balance and reproductive success. Further analyses, with larger number of samples, as well as assessment of additional biochemical parameters of fibrinolysis, should be performed to clarify the role of gene polymorphisms on fibrinolysis and consequently their influence on reproductive success.

Selected genetic causes of miscarriages

Approximately 15–25% of pregnancies end in spontaneous abortion, which is an expulsion from the mother body of the fetus weighing less than 500 g or before the 20th week of gestation. Determining abortions etiology is difficult due to its multifactorial character. Chromosomal abnormalities cause 38.6–80% of miscarriages. The largest group (93%) of chromosomal aberrations found in miscarried fetuses are numerical changes – aneuploidies and polyploidies. Much rarer (7%) are unbalanced structural aberrations, which can arise de novo or can be inherited from a carrier parent. In couples with spontaneous abortions, reciprocal chromosomal translocations (RCT) occur the most frequently, next are Robertsonian translocations and inversions. More complex chromosome abnormalities, e.g. double aneuploidies are found in 3.8% of fetuses. Another group of causes responsible for abortions are monogenic diseases of embryo or fetus resulting from autosomal dominant, autosomal recessive or X-linked mutations. Among mutations which may contribute to pregnancy loss are factor V Leiden gene mutations (c.1601G>A, earlier 1691G>A) and prothrombin gene mutation (c.97G>A, earlier 20210G>A). The research on mutations in candidate genes, eg.: ALOX15, CR1, CYP1A1, CYP17, CYP2D6, FOXP3, HLA-G, IL-6, KHDC3L, NLRP7, NOS3, PLK4, SYCP3, TLR3, TNF, TP53 and VEGFA is still ongoing.

Higher chromosomal abnormality rate in blastocysts from young patients with idiopathic recurrent pregnancy loss

OBJECTIVE

To determine whether the incidence of chromosomal abnormalities in blastocysts is higher in patients with idiopathic recurrent pregnancy loss (iRPL) who underwent preimplantation genetic testing for aneuploidy (PGT-A) than in those who underwent preimplantation genetic testing for monogenic defects (PGT-M).

DESIGN

Retrospective cohort study.

SETTING

University-affiliated reproductive center.

PATIENT(S)

A total of 62 patients with iRPL underwent 101 PGT-A cycles (iRPL group), and 212 patients underwent 311 PGT-M cycles (control group).

INTERVENTIONS(S)

Blastocyst biopsy and comprehensive chromosome screening technologies, including single-nucleotide polymorphism microarrays and next-generation sequencing.

MAIN OUTCOME MEASURE(S)

Incidence of chromosomal abnormalities in blastocysts and clinical miscarriage (CM) rate.

RESULT(S)

Stratification analysis by maternal age showed an increased incidence of chromosomal abnormalities in the iRPL group aged ≤35 years (48.9% vs. 36.9%), whereas no significant increase was found in the iRPL group aged >35 years (66.9% vs. 61.4%). After transfer of euploid embryos, women aged ≤35 years with iRPL exhibited an increased CM rate compared with the control group (26.1% vs. 3.1%).

CONCLUSION(S)

Young patients with iRPL have a significantly higher rate of chromosomal abnormalities in blastocysts compared with patients with no or sporadic CM. Although euploid embryos were transferred after PGT-A, young patients with iRPL had a higher CM rate, which may indicate that chromosomal abnormalities might not be the only causal factor for iRPL. Therefore, the role of PGT-A in iRPL still needs to be clarified.

Genetics of human female infertility†

About 10% of women of reproductive age are unable to conceive or carry a pregnancy to term. Female factors alone account for at least 35% of all infertility cases and comprise a wide range of causes affecting ovarian development, maturation of oocytes, and fertilization competence, as well as the potential of a fertilized egg for preimplantation development, implantation, and fetal growth. Genetic abnormalities leading to infertility in females comprise large chromosome abnormalities, submicroscopic chromosome deletion and duplications, and DNA sequence variations in the genes that control numerous biological processes implicated in oogenesis, maintenance of ovarian reserve, hormonal signaling, and anatomical and functional development of female reproductive organs. Despite the great number of genes implicated in reproductive physiology by the study of animal models, only a subset of these genes is associated with human infertility. In this review, we mainly focus on genetic alterations identified in humans and summarize recent knowledge on the molecular pathways of oocyte development and maturation, the crucial role of maternal-effect factors during embryogenesis, and genetic conditions associated with ovarian dysgenesis, primary ovarian insufficiency, early embryonic lethality, and infertility.

Family history and risk of miscarriage: A systematic review and meta-analysis of observational studies

INTRODUCTION

Miscarriage, a spontaneous pregnancy loss at <24 weeks' gestation, is a common complication of pregnancy but the etiologies of miscarriage and recurrent miscarriage are not fully understood. Other obstetric conditions such as preeclampsia and preterm birth, which may share similar pathophysiology to miscarriage, exhibit familial patterns, suggesting inherited predisposition to these conditions. Parental genetic polymorphisms have been associated with unexplained miscarriage, suggesting there could be a genetically inherited predisposition to miscarriage. This systematic review and meta-analysis of observational studies aimed to assess the association between family history of miscarriage and the risk of miscarriage in women.

MATERIAL AND METHODS

A systematic review and meta-analysis of observational studies was carried out in accordance with Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. Electronic searches using databases (MEDLINE, EMBASE and CINAHL) were carried out to identify eligible studies from 1946 until 2019. Observational studies (cohort or case-control) were included. Human studies only were included. Participants were women of reproductive age. Exposure was a family history of one or more miscarriage(s). The primary outcome was miscarriage in women. Abstracts were screened and data were extracted by two independent reviewers. Study quality was assessed using Critical Appraisal Skills Program (CASP) tools. Data were pooled from individual studies using the Mantel-Haenszel method to produce pooled odds ratios (ORs) with 95% confidence intervals (95% CI). Systematic review registration number (PROSPERO): CRD42019127950.

RESULTS

Thirteen studies were identified in the systematic review; 10 were eligible for inclusion in the meta-analysis. Twelve studies reported an association between family history of miscarriage and miscarriage in women. In all, 41 287 women were included in the meta-analysis. Women who miscarried were more likely to report a family history of miscarriage (pooled unadjusted OR 1.90, 95% CI 1.37-2.63). Overall study quality and size varied, with few adjusting for confounding factors. Results should be interpreted with caution as the associations presented are based on unadjusted analyses only.

CONCLUSIONS

Women who miscarry may be more likely to have a family history of miscarriage. Further research is required to confirm or refute the findings.

Factor V Leiden 1691G > A mutation and the risk of recurrent pregnancy loss (RPL): systematic review and meta-analysis

Background

Although numerous replication case-control studies have attempted to determine the association between Factor V Leiden (FVL) 1691G > A mutation and susceptibility to Recurrent pregnancy loss (RPL), there have been confliction among the results of various ethnic groups. To address this limitation, here we implemented first meta-analysis to provide with consistent conclusion of the association between FVL 1691G > A mutation and RPL risk.

Methods

After a systematic literature search, pooled odds ratio (OR) and their corresponding 95% confidence interval (CI) were used to evaluate the strength of the association. Additionally, meta-regression analyses were performed to find potential source of heterogeneity.

Results

In this meta-analysis, 62 studies, containing 10,410 cases and 9406 controls, were included in quantitative analysis. Overall population analysis revealed a significant positive association in the dominant (OR = 2.15, 95% CI = 1.84-2.50, P < 0.001), over-dominant (OR = 1.88, 95% CI = 1.61-2.19, P < 0.001), allelic (OR = 2.05, 95% CI = 1.79-2.35, P < 0.001), and heterozygote (OR = 1.97, 95% CI = 1.68-2.30, P < 0.001) models. Moreover, a significant association of dominant (OR = 3.04, 95% CI = 2.04-4.54, P < 0.001), over-dominant (OR = 2.65, 95% CI = 1.74-4.05, P < 0.001), and heterozygote (OR = 2.67, 95% CI = 1.81-4.22, P < 0.001) models was found in the Iranian population. The subgroup analysis indicated strong significant association in Asian, European, Africa population, and case-control studies but not in South Americans and cohort studies.

Conclusion

The FVL 1691G > A mutation and the risk of RPL confers a genetic contributing factor in increasing the risk of RPL, particularly in Iranians, except for South Americans.

Inherited susceptibility to miscarriage: a nested case-control study of 31,565 women from an intergenerational cohort

BACKGROUND

Miscarriage can be a devastating outcome for couples, and most miscarriages are unexplained. Many adverse obstetric outcomes (such as preeclampsia, preterm birth, and growth restriction) are thought to be inherited. It is possible that these conditions could share similar pathophysiologic mechanisms (such as endothelial dysfunction) with miscarriage. Therefore, it was hypothesized that there could be a susceptibility to miscarriage transmitted from mother to daughter.

OBJECTIVE

This study aimed to investigate the association between a maternal history of miscarriage and the risk of miscarriage in daughters.

STUDY DESIGN

A case-control study nested within an intergenerational cohort was conducted. Mother-daughter pairs were identified from the intergenerational cohort within the Aberdeen Maternity and Neonatal Databank, United Kingdom. A mother's history of miscarriage was the exposure. The primary outcome was miscarriage in daughters. There were 31,565 mother-daughter pairs who were eligible for inclusion. A population average model that used generalized estimating equations with robust standard errors was used to estimate the odds of a mother's history of miscarriage in daughters with a miscarriage compared with daughters with only livebirths. This method accounted for clustering of daughters within mothers, and multiadjusted analyses were performed to include confounders at the daughter's pregnancy level.

RESULTS

Daughters who miscarried had 11% greater odds of being born to mothers with a history of miscarriage (adjusted odds ratio, 1.11; 95% confidence interval, 1.01-1.22). Daughters with recurrent miscarriage (≥2) were also more likely to be born to a mother with a history of miscarriage (adjusted odds ratio, 1.25; 95% confidence interval, 1.04-1.49).

CONCLUSION

There may be an inherited predisposition to miscarriage transmitted from mother to daughter. Future research should investigate genetic or familial environmental factors that may predispose women to miscarriage.

The lncRNA SOX2OT rs9839776 C>T Polymorphism Indicates Recurrent Miscarriage Susceptibility in a Southern Chinese Population

Genetic susceptibility may be involved in the onset of recurrent miscarriage. Previous studies have shown that some genetic polymorphisms that regulate cell migration are associated with susceptibility to recurrent miscarriage. The SOX2 overlapping transcript (SOX2OT) may regulate the migration and invasion of multiple tumor cells and is related to susceptibility to various diseases. However, whether lncRNA SOX2OT polymorphisms are related to recurrent miscarriage susceptibility is unclear. Therefore, we investigated the relationship between the lncRNA SOX2OT rs9839776 C>T polymorphism and recurrent miscarriage susceptibility. We recruited 570 subjects with recurrent miscarriage and 578 healthy control subjects from a population in southern China and used the TaqMan method for genotyping. We found a significant association between the rs9839776 CT genotype in the SOX2OT gene and an increased risk for recurrent miscarriage (CT vs CC: adjusted OR = 1.357, 95%CI = 1.065 - 1.728, P = 0.0134). However, we did not observe any significant associations between the recurrent miscarriage risk and the number of miscarriages in different age groups. In conclusion, our study indicated that the rs9839776 CT genotype may contribute to an increased risk of recurrent miscarriage in the southern Chinese population and that rs9839776 may act as a prognostic biomarker in recurrent miscarriage patients. However, an experiment-based study with a larger sample size should be performed to confirm these results.

Associations between tumor necrosis factor-α and interleukin-6 polymorphisms and unexplained recurrent spontaneous abortion risk: A meta-analysis

To evaluate the associations between Tumor necrosis factor-α (TNF-α)(-238G>A) and Interleukin-6 (IL-6)(-174G>C) polymorphism and risk of unexplained recurrent spontaneous abortion (URSA).Correlated case-control studies were collected by computer retrieval. A meta-analysis was conducted by Stata 12.0 software to analysis the strength of association between polymorphism of TNF-α -238G>A and IL-6 -174G>C and URSA.Twenty-one articles with twenty-two studies were included, of which 12 and 10 studies were respectively related to mutation of TNF-α -238G>A, IL-6 -174G>C and URSA. The integrated results showed that the TNF-α-238G>A gene mutation was significantly correlated with the risk of URSA under homozygote model (AA vs GG;OR 1.533,95% CI 1.022-2.301) and recessive model (AA vs GG+AG;OR 1.571,95%CI 1.050-2.350)(P < .05). There was no association between URSA and TNF-α -238G>A under heterozygote model (AG vs GG;OR 0.963,95% CI 0.816-1.137), dominant model (AA+AG vs GG; OR 1.031,95%CI 0.880-1.209) and additive model (A vs G;OR 1.046,95%CI 0.909-1.203)(P > .05). The results of subgroup analysis based on ethnicity showed that -238G>A was significantly correlated with the risk of URSA in Asians under all gene models except for heterozygote model (AG vs GG; OR 1.129,95% CI 0.857-1.487) (P < .05). In Caucasians, it was dominant model (AA+AG vs GG; OR 1.430,95%CI 1.040-1.965) (P < .05) rather than others that showed relationship with URSA. From the integrated results, association was manifested between -174G>C and URSA under all gene models (P < .05) except for recessive model (CC vs GG+CG, OR 1.166, 95%CI 0.938-1.449) (P > .05), which is identical to subgroup analysis based on ethnicity.It is of great guiding significance for screening out and preventing URSA among high-risk women to test on TNF-α -238G>A and IL-6 -174G>C under gene models mentioned above which are highly associated with the risk of URSA, which can act as biological markers for URSA.

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 lncRNA CCAT2 rs6983267 G allele is associated with decreased susceptibility to recurrent miscarriage

Genetics might play various roles in susceptibility to recurrent miscarriage, and previous studies suggest that some gene polymorphisms might be associated with abortion and breast cancer onset. Colon cancer-associated transcript 2 (CCAT2) is a novel long noncoding RNA (lncRNA) transcript that might be correlated with susceptibility to multiple cancers, including breast cancer. However, whether lncRNA CCAT2 polymorphisms are related to susceptibility to recurrent miscarriage is unclear. We genotyped two lncRNA CCAT2 polymorphisms (rs6983267 and rs3843549) in 248 patients with recurrent miscarriage and 392 controls through a TaqMan real-time polymerase chain reaction assay, and the strength of each association was evaluated via 95% confidence intervals (CIs) and odds ratios (ORs). Our results showed that the rs6983267 G allele in lncRNA CCAT2 was associated with decreased susceptibility to recurrent miscarriage (TG vs. TT: adjusted OR = 0.603; 95% CI = 0.420-0.866; p = 0.0062; GG/TG vs. TT: adjusted OR = 0.620; 95% CI = 0.441-0.873; p = 0.0061). The combined analysis of the two protective polymorphisms (rs3843549 AA and rs6983267 TG/GG) revealed that individuals with two unfavorable alleles exhibited a lower risk of recurrent miscarriage than those with no or only one unfavorable allele (adjusted OR = 0.531; 95% CI = 0.382-0.739). Moreover, the decreased risk associated with the two protective alleles was most obvious in women aged less than 35 years (OR = 0.551; 95% CI = 0.378-0.8803; p = 0.0019) and in women with two to three miscarriages (adjusted OR = 0.466; 95% CI = 0.318-0.683; p < 0.0001). In conclusion, our study indicates that the rs6983267G allele might contribute to a decreased risk of recurrent miscarriage in the South Chinese population.

The lncRNA MALAT1 rs619586 G Variant Confers Decreased Susceptibility to Recurrent Miscarriage

Cardiovascula disease and recurrent miscarriage have shared risk factors, and some cardiovascular disease-related candidate genes have been confirmed to be associated with recurrent miscarriage. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA (lncRNA) that is considered to be associated with susceptibility to cardiovascular disease. However, whether lncRNA MALAT1 polymorphisms are related to recurrent miscarriage susceptibility is unclear. We genotyped three lncRNA MALAT1 polymorphisms (rs591291, rs619586, and rs3200401) in 284 patients and 392 controls using TaqMan methods. Logistic regression was used to evaluate the odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for age. Our results showed that the rs619586 G variant had protective effects against recurrent miscarriage (AG vs. AA: adjusted OR = 0.670, 95% CI = 0.457–0.982, p = 0.040; GG vs. AA: adjusted OR = 0.278, 95% CI = 0.079–0.975, p = 0.046; GG/AG vs. AA adjusted OR = 0.621, 95% CI = 0.429–0.900, p = 0.012). In a combined analyses of protective genotypes, with regard to the three single nucleotide polymorphisms (SNPs), we found that individuals with two or three protective genotypes exhibited a significantly lower risk of recurrent miscarriage than those with no or only one protective genotype (adjusted OR = 0.369, 95% CI = 0.199–0.684, p = 0.002). Moreover, the decrease in recurrent miscarriage risk with two or three protective genotypes was most pronounced in women less than 35 years of age (OR = 0.290, 95% CI = 0.142–0.589, p < 0.001) and in women with 2–3 miscarriages (adjusted OR = 0.270, 95% CI = 0.126–0.580, p < 0.001). In conclusion, our study suggests that the rs619586 G variant may have potential protective effects conferring a decreased risk of recurrent miscarriage in the southern Chinese population.

The interaction effect of angiogenesis and endothelial dysfunction-related gene variants increases the susceptibility of recurrent pregnancy loss

PURPOSE

The role of genetic polymorphisms in the pathogenesis of recurrent pregnancy loss (RPL) has been studied intensively. Complex diseases, including miscarriage, are believed to have a polygenic basis, and gene-gene interactions can play a significant role in the etiology of the disease. This study was conducted to investigate the association of gene-gene interactions with angiogenesis, endothelial dysfunction-related gene polymorphisms, and RPL.

METHODS

A case-control study was conducted with 253 unrelated RPL patients with 2 or more spontaneous pregnancy losses and 339 healthy women with no history of pregnancy complications. Genotyping of single-nucleotide polymorphisms (SNPs) was performed using real-time polymerase chain reaction (real-time PCR), restriction fragment length polymorphism (RFLP), or allele-specific polymerase chain reaction methods.

RESULTS

The genotypes 677TT of the MTHFR gene, 936TT, 936CT, and 634CC, 634GC of the VEGF gene, and allele 894T of the NOS3 gene were associated with a predisposition to RPL in the Russian population. A significant role of additive and epistatic effects in the gene-gene interactions of the SNPs of SERPINE-1, ACE, NOS3, MTHFR, and VEGF genes in RPL was demonstrated.

CONCLUSIONS

The results showed that gene-gene interactions are important for RPL susceptibility. Additionally, analysis of the genotype combinations of several allelic variants provides more information on RPL risk than analysis of independent polymorphic markers.

Investigating Association of rs5918 Human Platelets Antigen 1 and rs1800790 Fibrinogen β Chain as Critical Players with Recurrent Pregnancy Loss

Thrombophilia gene variants have been shown to be associated with higher risk of recurrent pregnancy loss (RPL). Due to the role of human platelets antigen 1 (HPA-1) and fibrinogen β chain (FGB) as critical players in the coagulation process, their most important variants including rs5918 T > C and rs1800790 G > A were selected to be studied in women affected by RPL. Three milliliters of peripheral blood were drawn from 110 women with history of at least two consecutive spontaneous abortion and 110 healthy women controls. rs5918 T > C and rs1800790 G > A of HPA-1 and FGB genes, respectively, were selected to be analyzed through polymerase chain reaction-restriction fragment length polymorphism (PCR_RFLP) following DNA isolation using QIAamp DNA Blood Mini Kit. Heterozygote genotype (TC) of HPA-1 gene rs5918 polymorphism was significantly associated with risk of RPL (p-value = 0.02). Although, rs1800790 G > A of FGB gene was not associated with RPL, its combination with rs5918 polymorphism was associated with increased risk of RPL. Owing to the critical roles of FGB and HPA-1 genes in coagulation, and thrombosis and several confinements on the meaningful association between the combination of those polymorphism with risk of RPL, including them in the thrombophilia panel may increase detection rate of hereditary thrombophilia patients. However, further studies with larger sample sizes are required to shed light on the exact role of the studied gene polymorphism, especially rs1800790 G > A of FGB gene variant in pathogenesis of RPL.

Genetic association between HLA-G 14-bp polymorphism and diseases: A systematic review and meta-analysis

BACKGROUND

HLA-G is an immune checkpoint molecule. Since a differential molecule expression has been reported even for healthy individuals, many studies have focused on polymorphisms at HLA-G regulatory regions, particularly the 3' untranslated region (3'UTR). The presence/absence of a 14-bp sequence was the first polymorphism described and it is the most studied in association between HLA-G and disorders.

METHODS

In this study, we performed a systematic review and meta-analysis of all association studies published regarding the HLA-G 14-bp.

RESULTS

We verified association between 14-bp alleles and diseases in the following situations: (1) presence of 14-bp (insertion) conferred susceptibility to preeclampsia (child alleles evaluated) and systemic lupus erythematosus (OR = 1.42; 95%CI = 1.04-1.93; p = 0.026 and OR = 1.13; 95%CI = 1.01-1.27, p = 0.028); (2) 14-bp absence (deletion) was associated with increased risk to breast cancer (OR = 1.23; 95%CI = 1.06-1.43; p = 0.006) and human Cytomegalovirus infection (OR = 2.06; 95%CI = 1.60-2.64; p < 0.0001); and (3) a risk association was observed between the group of reproductive disorders and the 14-bp insertion (OR = 1.12; 95%CI = 1.01-1.24; p = 0.034).

CONCLUSIONS

Considering that others 14-bp associations were inconclusive and that other variation sites observed at HLA-G 3'UTR exhibit a proven role on post-transcriptional regulation of HLA-G expression, the complete 3'UTR segment should be analyzed in terms of disease susceptibility, instead of a single polymorphism.

Evolutionary justifications for human reproductive limitations

Common human reproductive inefficiencies have multiple etiologies. Going against chance, many effects, such as polycystic ovaries, endometriosis, and folate metabolic issues, have genetic components, while aneuploid losses arise from diverse mitotic and meiotic errors at different stages, some transitory. This can be advantageous, since greater overall survival with fewer offspring can increase reproductive success. Benefits primarily accrue to mothers, who bear most child related costs, and for whom early losses are less costly than late. Different adaptations to different situations reflect human evolutionary history. For early speciation, periodic climate extremes repeatedly reduced resources, favoring limitations while contracted populations helped fix relevant genes. Later, under better conditions, evolving social cooperation could increase fecundity faster than it added resources, further supporting reproductive suppression through mitotic aneuploidy, with very early losses minimizing maternal costs. The grandmother hypothesis suggests benefits in limiting reproduction as maternal age increased pregnancy risks in order to support grandchildren as they arrived, selecting for maternal age-related meiotic aneuploidy. Finally, with variable short-term agricultural shortages, acute reproductive responses arose through chromatin "nutrient sensor"-regulated epigenetic effects that also shifted some lethal effects earlier, reducing both maternal and mutation load costs. Overall, despite suggestions to the contrary, it is likely that human selective pressures have not decreased with civilization, but that many of the costs have been shifted to early reproduction.

Chromosomal abnormalities in recurrent miscarriages by conventional karyotyping analysis

Abstract Objectives: to describe the prevalence and types of chromosomal abnormalities in couples with recurrent miscarriage and products of conception. Methods: electronic searches were performed in the PubMed/Medline database and in the Portal Regional da Biblioteca Virtual em Saúde/BVS (Regional Website of the Virtual Library in Health/BVS) using the descriptors “chromosomal abnormalities and abortions and prevalence”. After applying the inclusion and exclusion criterias, 17 studies were selected. Results: 11 studies were conducted in couples with recurrent miscarriage and six in products of conception. The main results of the couples with recurrent miscarriage were: the frequency of chromosomal abnormalities which varied from 1.23% to 12% and there was a predominance alteration of the chromosomal structures (reciprocal translocations, followed by Robertsonian). In products of conception, the results observed were: the frequency of chromosomal abnormality was above 50% in approximately 70% of the studies; there was a predominance alteration of the numerical chromosomal (trisomy - chromosomes 16, 18, 21 and 22, followed by polyploidy and monosomy X). Conclusions: in summary, cytogenetic alterations represent an importante cause of pregnancy loss and its detection can help couples with genetic counseling. Therefore, the value of knowledge on the prevalence of cytogenetic abnormalities in miscarriage samples is unquestionable, once it is permitted a proper genetic counseling for the couple.

The methylenetetrahydrofolate reductase c.c.677 C>T and c.c.1298 A>C polymorphisms in reproductive failures: Experience from an RSA and RIF study on a Polish population

Almost 1600 individuals from the Polish population were recruited to this study. Among them 319 were fertile couples, 289 were recurrent spontaneous abortion (RSA) couples, and 131 were in the group of recurrent implantation failure (RIF) following in vitro fertilization. The aim of this study was to evaluate the MTHFR c.c.677 C>T and c.c.1298 A>C polymorphisms’ association with RSA and RIF. We used PCR-RFLP with HinfI (677 C>T) and MboII (1298 A>C) digestion. We observed a protective effect of the female AC genotype (OR = 0.64, p = 0.01) and the C allele (AC+CC genotypes; OR = 0.65, p = 0.009) against RSA. Moreover, 1298 AA/677 CT women were more frequent in RSA (31.14%) and RIF (25.20%) groups in comparison to fertile women (22.88%), although this difference was significant only in the case of RSA (p = 0.022, OR = 1.52). Male combined genotype analysis revealed no association with reproductive failure of their partners. Nevertheless, the female/male combination AA/AC of the 1298 polymorphism was more frequent in RSA couples (p = 0.049, OR = 1.49). However, the significant results became insignificant after Bonferroni correction. In addition, analysis of haplotypes showed significantly higher frequency of the C/C haplotype (1298 C/677 C) in the female control group than in the female RSA group (p = 0.03, OR = 0.77). Moreover, the association between elevated homocysteine (Hcy) level in plasma of RSA and RIF women and MTHFR polymorphisms was investigated but did not reveal significant differences. In conclusion, for clinical practice, it is better to check the homocysteine level in plasma and, if the Hcy level is increased, to recommend patients to take folic acid supplements rather than undergo screening of MTHFR for 1298 A>C and 677 C>T polymorphisms.

Recurrent pregnancy loss: current perspectives

Recurrent pregnancy loss is an important reproductive health issue, affecting 2%–5% of couples. Common established causes include uterine anomalies, antiphospholipid syndrome, hormonal and metabolic disorders, and cytogenetic abnormalities. Other etiologies have been proposed but are still considered controversial, such as chronic endometritis, inherited thrombophilias, luteal phase deficiency, and high sperm DNA fragmentation levels. Over the years, evidence-based treatments such as surgical correction of uterine anomalies or aspirin and heparin for antiphospholipid syndrome have improved the outcomes for couples with recurrent pregnancy loss. However, almost half of the cases remain unexplained and are empirically treated using progesterone supplementation, anticoagulation, and/or immunomodulatory treatments. Regardless of the cause, the long-term prognosis of couples with recurrent pregnancy loss is good, and most eventually achieve a healthy live birth. However, multiple pregnancy losses can have a significant psychological toll on affected couples, and many efforts are being made to improve treatments and decrease the time needed to achieve a successful pregnancy. This article reviews the established and controversial etiologies, and the recommended therapeutic strategies, with a special focus on unexplained recurrent pregnancy losses and the empiric treatments used nowadays. It also discusses the current role of preimplantation genetic testing in the management of recurrent pregnancy loss.

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.