Risk Of Recurrent Implantation Failure Research Articles

Correlation between Serum Levels of HLA-G and Recurrent Implantation Failure During Implantation Window in Women Undergoing In Vitro Fertilization

Background: Recurrent implantation failure (RIF) during artificial reproductive techniques (ARTs) remains a health problem. Many physiopathological pathways have been proposed for RIF, but the causes are not yet clear. Thus, the purpose of the current study was to evaluate the possible correlation between human leucocyte antigen-G (HLA-G) serum levels and recurrent implantation failure during the implantation window in women undergoing In vitro fertilization (IVF). Materials and Methods: In this prospective case-control study, 39 patients with RIF and 20 cases with successful implantation were enrolled as the control group. HLA-G serum levels were measured using the sandwich ELISA method in both groups. Results: HLA-G serum levels in the RIF group were significantly higher than in controls (0.085 ± 0.019 compared to 0.073 ± 0.005, p = 0.024). Furthermore, by grouping patients based on age and BMI, we found that in the cases with ages above 30 years and with BMI more than 25 (kg/m2), HLA-G serum levels in the RIF group were remarkably greater than controls (0.088 ± 0.019 compared to 0.072 ± 0.004, p = 0.002 and 0.083 ± 0.012 compared to 0.072 ± 0.003, p = 0.021, respectively). Conclusion: Serum levels of HLA-G increase in the RIF patients, especially in cases of patients above 30 years old and those with BMI ≥ 25, which remains significant after eliminating confounding variables. These results may indicate the involvement of physiopathological pathways of HLA-G in the increasing risk of RIF.

O-034 Specific KIR gene profiles and recurrent implantation failure

Abstract Study question Is there a link between killer cell immunoglobulin-like receptors (KIRs) genes, haplotypes, or genotypes and recurrent implantation failure (RIF)? Summary answer The KIRAA1 genotype significantly increases the risk of RIF. The presence of the full-length receptor KIR2DS4norm in KIRAA haplotype patients is indicative of RIF development. What is known already KIRs are expressed by a subset of uterine natural killer cells (uNK cells). The KIRs family consists of 16 genes with high polymorphism that are divided into two main haplotypes: KIRAA and KIRBx. The KIRAA haplotype consists mostly of inhibitory KIRs and only one activating receptor, KIR2DS4, whose function is uncertain, whereas the Bx haplotype has a diverse gene composition, with a focus on activating receptor genes. The primary difference is in the balance of KIRs, which can activate or inhibit uNKcells’ ability to produce components required for embryo-implantation, and hence they are thought to being implicated in RIF. Study design, size, duration A three-year observational cohort research was conducted at a private infertility centre. A total of 82 patients were genotyped for activating or inhibiting KIR genes. The study included 60 ovarian normo-responders under the age of 40, with 28 women with repeated implantation failure serving as the study group and 32 as controls. Participants/materials, setting, methods DNA was extracted from blood samples of all participants, including RIF patients and controls. The 16 KIR genes were investigated utilizing PCR with Sequence-Specific Primer (SSP) technique. Individual KIR gene profiles, KIRAA and KIRBx haplotypes, and their unique genotypes were detected by software analyses of the collected data based on the reaction pattern when compared to patterns associated with described KIR gene sequences. All data were statistically analysed with the Fisher Exact Test. Main results and the role of chance The frequencies of the two main haplotypes, KIR AA and KIR Bx, were 28% and 72%, respectively. Patients with more inhibitory KIR genes (haplotype KIR AA) had a higher rate of RIF (60% vs 40% in controls; P = 0.2) than those with KIR Bx phenotypes (37.5% RIF vs 62.5% controls; p = 0.026). Further analysis of KIR AA revealed two genotypes: KIR AA 1 (31.82%) and KIR AA195 (68.18%). The KIR2DS4 locus in the full-length receptor (KIR2DS4-norm) was only expressed in KIR AA1. The distribution of RIF occurrences in the two different genotypes demonstrates a significant increase in the number of RIF in the possessors of KIR AA1 (75% vs 15%, p = 0.01), with no significant difference between the two groups in the KIR AA195. Limitations, reasons for caution The study encompasses small samples but the association strength was noticeably high, which confers the findings more confidence. Wider implications of the findings These findings imply that women with a high proportion of inhibited KIR genes (haplotype KIR AA) and KIR2DS4norm are more likely to develop RIF. Trial registration number NA

Centromeric AA motif in KIR as an optimal surrogate marker for precision definition of alloimmune reproductive failure

Throughout pregnancy, the decidua is predominantly populated by NK lymphocytes expressing Killer immunoglobulin-like receptors (KIR) that recognize human leukocyte antigen-C (HLA-C) ligands from trophoblast cells. This study aims to investigate the association of KIR-HLA-C phenotypes in couples facing infertility, particularly recurrent pregnancy loss (RPL) and recurrent implantation failure (RIF), in comparison to a reference population and fertile controls. This observational, non-interventional retrospective case–control study included patients consecutively referred to our Reproductive Immunology Unit from 2015 to 2019. We analyzed the frequencies of KIR and HLA-C genes. As control groups, we analyzed a reference Spanish population for KIR analysis and 29 fertile controls and their male partners for KIR and HLA-C combinations. We studied 397 consecutively referred women with infertility and their male partners. Among women with unexplained RPL (133 women) and RIF (176 women), the centromeric (cen)AA KIR genotype was significantly more prevalent compared to the reference Spanish population (p = 0.001 and 0.02, respectively). Furthermore, cenAA was associated with a 1.51-fold risk of RPL and a 1.2-fold risk of RIF. Conversely, the presence of BB KIR showed a lower risk of reproductive failure compared to non-BB KIR (OR: 0.12, p < 0.001). Women and their partners with HLA-C1C1/C1C1 were significantly less common in the RPL-Group (p < 0.001) and RIF-Group (p = 0.002) compared to the control group. Moreover, the combination of cenAA/C1C1 in women with C1C1 partners was significantly higher in the control group than in the RPL (p = 0.009) and RIF (p = 0.04) groups, associated with a 5-fold increase in successful pregnancy outcomes. In our cohort, the cenAA KIR haplotype proved to be a more accurate biomarker than the classic AA KIR haplotype for assessing the risk of RPL and RIF, and might be particularly useful to identify women at increased risk among the heterogeneous KIR AB or Bx population. The classification of centromeric KIR haplotypes outperforms classical KIR haplotypes, making it a better indicator of potential maternal–fetal KIR-HLA-C mismatch in patients.

Paternal thrombophilia and recurrent implantation failure: an exploratory case-control study.

Many pieces of literature have reported that inherited and acquired thrombophilia might be a risk factor for recurrent implantation failure (RIF), however, most studies have only focused on RIF patients and not their male partners. We studied the possible association of paternal thrombophilia with RIF risk. Forty-two male partners aged 20-45 suffered from RIF compared with 42 males from couples with at least one successful pregnancy. All participants were investigated for thrombophilia markers. The prevalence of coagulation Factor V activity was significantly higher in the case group (42.9%) than in the control group (16.7%) (p=0.008) (OR=3.75; 95% CI, 1.38, 10.12). The prevalence of protein C and protein S deficiencies in RIF patients were 4.8% and 2.4%, respectively, and 0% in the controls. The prevalence of antithrombin III (ATIII) deficiency was significantly higher in the case group (19%) than in the control group (2.4%) (p=0.01). None of MTHFR C677T and MTHFR A1298C were statistically significant between the two groups. Combined thrombophilia was 45.2% in the men of the RIF group when compared with the control, 14.2% (p=0.001) (OR = 4.95; 95% CI, 1.75-13.86). Paternal thrombophilia may be related to recurrent implantation failure, so evaluation of this factor in RIF patients could be used to identify relevant risk groups and may help in the proper management of these cases to enhance the chance of implantation.

The relevance of prothrombotic genetic variants in women who experienced pregnancy loss or embryo implantation failure: A retrospective analysis of 1922 cases.

The aim of our study was that to assess the allelic and genotype frequencies of nine prothrombotic gene variants in patients with a history of pregnancy loss and recurrent pregnancy loss (RPL). Women who underwent assisted reproductive technology (ART) with ongoing pregnancy and those with recurrent implantation failure (RIF) were also included. Nine prothrombotic gene variants were evaluated: factor V Leiden (FVL), factor V, H1299R variant (FVR2), factor II (FII) G20210A, methylene-tetrahydrofolate reductase (MTHFR) C677T and A1298C, beta-fibrinogen -455G>A, factor XIII (FXIII) V34L, human platelet antigen-1 (HPA-1) L33P variants, and plasminogen activator inhibitor-1 (PAI-1) 4G/5G. The following study groups were assessed: (1) women who experienced one (n = 334) or two (n = 264) episodes of pregnancy loss; (2) 468 women who experienced RPL; (3) 214 women who underwent ART followed by ongoing pregnancies; and (4) 282 women who experienced RIF after ART, that is, three or more consecutive implantation failures following high-quality embryo transfers to the uterus with an appropriate endometrium. As control group, 430 subjects from the general population were enrolled. FVL, the -455G>A variant of beta-fibrinogen, and PAI-1 4G were associated with a higher risk of developing RPL compared with the general population. Furthermore, FVL, FVR2, FII G20210A and MTHFR C677T conferred a significantly higher risk of RIF in women who performed ART compared with the general population. No statistical differences between the general population and other study groups were observed. Specific prothrombotic genetic variants are more frequently expressed in women with RPL and RIF, supporting their role in the development of polimicrothrombosis and impairing the invasion during embryo implantation.

Genetic Correlation of miRNA Polymorphisms and STAT3 Signaling Pathway with Recurrent Implantation Failure in the Korean Population

The growing prevalence of in vitro fertilization-embryo transfer procedures has resulted in an increased incidence of recurrent implantation failure (RIF), necessitating focused research in this area. STAT3, a key factor in maternal endometrial remodeling and stromal proliferation, is crucial for successful embryo implantation. While the relationship between STAT3 and RIF has been studied, the impact of single nucleotide polymorphisms (SNPs) in miRNAs, well-characterized gene expression modulators, on STAT3 in RIF cases remains uncharacterized. Here, we investigated 161 RIF patients and 268 healthy control subjects in the Korean population, analyzing the statistical association between miRNA genetic variants and RIF risk. We aimed to determine whether SNPs in specific miRNAs, namely miR-218-2 rs11134527 G&gt;A, miR-34a rs2666433 G&gt;A, miR-34a rs6577555 C&gt;A, and miR-130a rs731384 G&gt;A, were significantly associated with RIF risk. We identified a significant association between miR-34a rs6577555 C&gt;A and RIF prevalence (implantation failure [IF] ≥ 2: adjusted odds ratio [AOR] = 2.264, 95% CI = 1.007–5.092, p = 0.048). These findings suggest that miR-34a rs6577555 C&gt;A may contribute to an increased susceptibility to RIF. However, further investigations are necessary to elucidate the precise mechanisms underlying the role of miR-34a rs6577555 C&gt;A in RIF. This study sheds light on the genetic and molecular factors underlying RIF, offering new avenues for research and potential advancements in the diagnosis and treatment of this complex condition.

Association of human leukocyte antigen-G and -F with recurrent miscarriage and implantation failure: A systematic review and meta-analysis.

The immune system plays an essential role in embryonic implantation and pregnancy, but the molecular details remain controversial. In the past four decades, human leukocyte antigen (HLA)-G and -F have garnered significant attention. MEDLINE, EMBASE, Web of Science, and the Cochrane Trials Registry were searched from their inception dates until December 2022. Studies were selected following PRISMA guidelines. Meta-analyses were used to assess the relationship of soluble HLA-G (sHLA-G) and HLA-G 3'-untranslated region polymorphisms with recurrent miscarriage (RM) and recurrent implantation failure (RIF). Narrative synthesis was conducted to determine the association of RM with other single nucleotide polymorphisms (SNPs) and HLA-G protein in tissues and of RIF with HLA-F. Risk-of-bias was assessed using ROBINS-I. Publication bias was assessed using Egger's and Begg's tests. Finally, 42 articles were eligible for inclusion in the systematic review (32 in the meta-analysis; 13 in narrative synthesis). We found a significant association between the 14-bp ins/del HLA-G polymorphism and RM risk, but no definitive association with RIF risk. Women with RM had lower blood concentrations of sHLA-G during pregnancy and non-pregnancy than did controls. For women in the RIF group, no significant difference was found. HLA-G protein and gene expression levels may be closely related to RM. The relevance of HLA-G to RIF is still being determined. A narrative synthesis of current studies has shown that HLA-F is likely associated with RIF.

Association of Polymorphisms in FSHR, INHA, ESR1, and BMP15 with Recurrent Implantation Failure.

Recurrent implantation failure (RIF) refers to two or more unsuccessful in vitro fertilization embryo transfers in the same individual. Embryonic characteristics, immunological factors, and coagulation factors are known to be the causes of RIF. Genetic factors have also been reported to be involved in the occurrence of RIF, and some single nucleotide polymorphisms (SNPs) may contribute to RIF. We examined SNPs in FSHR, INHA, ESR1, and BMP15, which have been associated with primary ovarian failure. A cohort of 133 RIF patients and 317 healthy controls consisting of all Korean women was included. Genotyping was performed by Taq-Man genotyping assays to determine the frequency of the following polymorphisms: FSHR rs6165, INHA rs11893842 and rs35118453, ESR1 rs9340799 and rs2234693, and BMP15 rs17003221 and rs3810682. The differences in these SNPs were compared between the patient and control groups. Our results demonstrate a decreased prevalence of RIF in subjects with the FSHR rs6165 A>G polymorphism [AA vs. AG adjusted odds ratio (AOR) = 0.432; confidence interval (CI) = 0.206-0.908; p = 0.027, AA+AG vs. GG AOR = 0.434; CI = 0.213-0.885; p = 0.022]. Based on a genotype combination analysis, the GG/AA (FSHR rs6165/ESR1 rs9340799: OR = 0.250; CI = 0.072-0.874; p = 0.030) and GG-CC (FSHR rs6165/BMP15 rs3810682: OR = 0.466; CI = 0.220-0.987; p = 0.046) alleles were also associated with a decreased RIF risk. Additionally, the FSHR rs6165GG and BMP15 rs17003221TT+TC genotype combination was associated with a decreased RIF risk (OR = 0.430; CI = 0.210-0.877; p = 0.020) and increased FSH levels, as assessed by an analysis of variance. The FSHR rs6165 polymorphism and genotype combinations are significantly associated with RIF development in Korean women.

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

Research questionThe 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)? DesignProspective 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. ResultsOver-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). ConclusionsThese 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.

Association of rs1570360 and rs2010963 in VEGF and rs2279744 in the MDM2 gene with Recurrent Implantation Failure in Iranian Women.

The embryo implantation includes a complex sequence of signaling events, comprising numerous molecular mediators, such as ovarian hormones, cytokines, adhesion molecules and, growth factors. One of the critical factors in angiogenesis is the vascular endothelial growth factor (VEGF). The VEGF plays a pivotal role in embryonic development, decidua vascularization and placental angiogenesis. Furthermore, the P53 gene and its negative regulator, murine double minute 2 (MDM2), are major players in reproductive processes. This study aimed to assess the association of polymorphisms of the VEGF and the MDM2 genes with idiopathic recurrent implantation failure. We genotyped 60 women with previous idiopathic recurrent implantation failures and 60 fertile women as controls. Restriction Fragment Length Polymorphism (RFLP) and Sanger sequencing were used for genotyping the rs2010963 and the rs1570360 polymorphisms in VEGF; and the rs2279744 in MDM2 genes. Results indicated a higher frequency of the VEGF rs1570360 AA genotype and A allele in patients with a history of idiopathic implantation failure [OR=6.4 (1.22 - 33.64), p-value=0.02)]. However, the frequency of VEGF +405 G/C and MDM2 SNP309 T/G [(OR=3 (0.5 - 16) p-value=0.2, OR=1.18 (0.3 - 3.7) p-value=0.7, respectively)] genotypes were not significantly different between cases and controls. The VEGF polymorphism may influence embryo implantation and the VEGF rs1570360 AA genotype may predispose to the risk of recurrent implantation failure after IVF.

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

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. 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. 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. 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.

P-367 Centromeric motif AA of the KIR: the best subrogate marker that defines Alloimmune Reproductive Failure

Abstract Study question Should the centromeric and telomeric motifs been studied separately and taked them in to account in women with recurrent reproductive failure? Summary answer The results show that when the classic KIR study is performed, there is a 12,5% of AA centromeric KIR patients with reproductive failure unidentified. What is known already During human pregnancy, the decidua is mainly populated by NK lymphocytes that express immunoglobulin-type receptors (KIR) recognizing their HLA-C ligands from trophoblast. The objective of this study was to analyze the association of KIR-HLAC phenotypes in couples with sterility, recurrent pregnancy loss (RPL), recurrent implantation failure (RIF), and fetal death (FD) in comparison with reference population and fertile control. Study design, size, duration It is a retrospective real-life observational study from 2015 to 2019 Participants/materials, setting, methods The frequency of the KIR and HLA-C genes were analyzed in 397 women and their partners with reproductive failure. We compare them with 33 fertile controls and reference Spanish population. KIR and HLA-C genotypes of the patients and controls were determined by Lifecodes Sequence-Specific Oligonucleotides (SSO) Typing KIT (Diagnostica Longwood®) performed at Centro de Transfusiones de la Comunidad de Madrid and those of controls at the Hospital Universitario Clínico San Carlos. Main results and the role of chance Centromeric (Cen) AA was the most frequent KIR genotype in women with unexplained RPL and RIG with respect to reference Spanish population (p = 0.001 and 0.02, respectively). Moreover, cenAA was associated with 1.51-fold risk of RPL and 1.2-fold risk of RIF. On the other hand, BB KIR showed lower risk of any reproductive failure tan non-BB KIR (0.12; p &amp;lt; 0.001). HLA-C1C1/C1C1 women and partner were significantly lower in RPL-Group (p &amp;lt; 0.001) and RIF-Group (p = 0.04). Indeed, the combination cenAA/C1C1 women with C1C1 partners were significantly higher in the control group compared with RPL (p = 0.009) and RIF (0.04) with 5-fold of successful pregnancy outcome. In our cohort, cenAA KIR was a more accurate biomarker tan classic AA KIR haplotype for RPL- and RIF-associated risk. Limitations, reasons for caution The fact of having stratified a lot by groups means that a small number of patients is obtained in each subgroup, which makes it more difficult to conclude the results. Wider implications of the findings Our study demonstrates the importance of the complete KIR genotype study, which would give us more comprehensive information on the behavior of NK cells, moreover we propose that centromeric KIR classification is superior to the KIR classical haplotypes, better identifying those patients with potential KIR-HLA-C mismatch. Trial registration number Not applicable

Three Oxidative Stress-Related Genes That Associate Endometrial Immune Cells Are Considered as Potential Biomarkers for the Prediction of Unexplained Recurrent Implantation Failure.

Recurrent implantation failure (RIF) represents a new challenge in the field of assisted reproductive technology (ART). Considering the known effects of immune cell regulation on embryo implantation process, as well as our gene set variation analysis (GSVA) results that suggested the association between RIF and pathways of oxidative stress and immune responses, we hypothesized that oxidative stress- related genes (OSGs) associated with aberrant immunological factor may represent novel biomarkers for unexplained RIF. We therefore screened out the immune cell coexpressed OSGs by performing CIBERSORT, LM22 matrix and Pearson correlation, followed by constructing an OSG signature by least absolute shrinkage and selection operator (LASSO) regression. Three OSGs (AXL, SLC7A11 and UBQLN1) were then identified to establish a RIF risk signature, which showed high ability to discriminating RIF from fertile control. A nomogram was established, with a free online calculator for easier clinical application. Finally, Chilibot, protein-protein interaction analysis and BioGPS were sequentially applied for the investigation of functional relationships of these three genes with RIF and other OSGs, as well as their expression abundance across different human tissues. In conclusion, we identified an OSG signature that are relevant novel markers for the occurrence of unexplained RIF.

APOE polymorphism status (E4) may help in predicting the risk of recurrent implantation failure.

To examine the association between apolipoprotein E (APOE) gene polymorphisms and incidence of recurrent implantation failure (RIF). In a case-control study, 100 women with RIF were compared with 100 women with at least one live child. DNA was extracted from the peripheral blood and APOE genotyping was performed through polymerase chain reaction, followed by restriction fragment length polymorphism. Statistical analysis was performed using Pearson's χ2 test. Our data revealed a significantly higher frequency for the E3/E4genotype and E4 allele in the RIF group compared with controls. Significant differences in frequencies of the E4 allele (odds ratio [OR] 2.176; 95% confidence interval [CI] 1.131-4.185; P=0.026) and E3/E4genotype (OR 2.203; 95% CI 1.092-4.443; P=0.038) were observed between the groups. The E4 polymorphism is correlated with RIF occurrence in women undergoing assisted reproductive treatment and potentially can be considered as a risk factor to the human implantation process.

PAI-1 4G/4G Genotype Is Associated with Recurrent Implantation Failure: a Systematic Review and Meta-analysis.

To detect the association between PAI-1 -675 4G/5G polymorphism and recurrent implantation failure (RIF). We performed this meta-analysis by searching databases of PubMed, EMBASE, OVID, and CNKI (China National Knowledge Infrastructure) for case-control studies that evaluated the association between PAI 4G/5G polymorphism and RIF. Meta-analysis was performed using the random-effects model. The odds ratios (ORs) with 95% confidence intervals (CIs) were reported to evaluate the association. Meta-regression and subgroup analysis were performed to explore the source of heterogeneity. Sensitivity analysis and trim-and-fill analysis were performed to explore the robustness of the meta-analysis. Eight case-control studies consisted of 1273 women were included in this meta-analysis (including 697 RIF patients and 576 control participants). The combined results showed that the homozygous genotype of PAI-1 -675 4G/4G was significantly associated with RIF (OR 2.79, 95%CI 1.53-5.08, P-value = 0.0008). Meta-regression and subgroup analysis showed that sample origin is the primary source of heterogeneity (P-value for meta-regression: 0.005). Study quality also explains some heterogeneity (P-value for meta-regression: 0.03). Sensitivity analysis showed that the result was not significantly changed after excluding one study each time. Trim-and-fill analysis showed that the result was not significantly changed after filled with three studies. PAI -675 4G/4G genotype may serve as one of the predisposing factors of RIF. Women with PAI-1 4G/4G genotype were at higher risk of RIF. However, more high-quality studies are needed to confirm the conclusion.

The association between Angiopoietin-2 and the risk of recurrent implantation failure

Objectives: to assess the possible association between Angiopoietin-2 (ANGT-2) and the risk of recurrent implantation failure and to determine the possible role of it in the successfulness of in vitro fertilization process. Methods: A case control study was done on 80 female patients with Recurrent Implantation Failure (RIF) and 23 female patients with successful in-vitro fertilization (IVF) who were recruited from the Department of Obstetrics and Gynecology at Al Imamain Al-Kadhimain Medical City, Baghdad, Iraq between January and September 2019. The levels of ANGT-2 were measured in the serum of women with RIF and successful IVF and compared with those with a positive IVF and control group that comprise 74 age, BMI and sex-matched apparently healthy females. Results: The data revealed that there was a significant (p=0.007) decrease in ANGPT2 levels (2914.66±834.08) in women with recurrent implantation failure (RIF) in a comparison with controls (3235.83 ±444.16) whereas non-significant (p&gt;0.05) differences were obtained between women with a successful in vitro fertilization (+ve IVF) and controls and also with RIF group. Conclusions: the possible association between ANGT-2 and the risk of RIF and the possibility of using it as a marker for a prognosis in women subjected to IVF process

Polymorphisms of vascular endothelial growth factor and recurrent implantation failure: a systematic review and meta-analysis.

To investigate the associations between polymorphisms of vascular endothelial growth factor (VEGF) with recurrent implantation failure (RIF). We performed the systematic review and meta-analysis by searching databases of PubMed, EMBASE, OVID, and CNKI (China National Knowledge Infrastructure) for studies that evaluated the associations between VEGF polymorphisms with RIF. Meta-analysis was performed if the polymorphism was studied by more than two case-control studies. Data were analyzed using R software. Odds ratios (ORs) with 95% confidence intervals (CIs) were reported to assess the associations. Nine VEGFpolymorphisms (-1154G > A, -460T > C, +405G > C, -7C > T, -634C > G, -2578C > A, +936C > T, 5C > T, -583C > T) were systematically reviewed. Meta-analysis was performed on VEGF -1154 G > A polymorphism. Three case-control studies consisted of 683 women were included in the quantitative meta-analysis (305 RIF patients and 378 controls). Results showed that VEGF -1154A allele was significantly associated with RIF (OR 1.39, 95% CI 1.08-1.78, P-value = 0.01). The dominant genetic model showed that VEGF 1154AA plus VEGF 1154AG genotypes were more frequent in RIF patients than VEGF 1154GG genotype (OR 1.56, 95% CI 1.10-2.20, P-value = 0.01). However, the result under the recessive genetic model showed no significant difference (OR 1.67, 95% CI 0.92-3.03, P-value = 0.09). VEGF -1154A allele may serve as one of the predisposing factors of RIF. Women with VEGF 1154 AA/GA genotypes were at higher risk of RIF. However, we should consider the haplotype effect of VEGF polymorphisms in future studies.

Association between microRNA machinery gene polymorphisms and recurrent implantation failure.

The present study aimed to investigate the potential association of five miRNA machinery gene polymorphisms (DICER1 rs3742330A>G, DROSHA rs10719T>C, RAN rs14035C>T, XPO5 rs11077A>C and DGCR8 rs417309G>A) with recurrent implantation failure (RIF), a clinical condition in which good-quality embryos repeatedly fail to implant following two or more in vitro fertilization cycles, and its associated risk factors in Korean women. Therefore, the present study performed genotype analysis and assessed the frequency of these miRNA gene polymorphisms in patients diagnosed with RIF (n=119) and randomly selected controls (n=210) with at least one live birth and no history of pregnancy loss. The DROSHA rs10719T>C and RAN rs14035C>T polymorphisms were identified to be significantly associated with decreased prevalence of RIF. Additionally, the DROSHA rs10719 TC and the RAN rs14035 CT genotypes were present at significantly lower frequencies in the RIF group than in the control group (adjusted odds ratio=0.550; 95% CI, 0.339-0.893; P=0.016; and adjusted odds ratio=0.590; 95% CI, 0.363-0.958; P=0.033, respectively). Furthermore, the combined RAN rs14035 CT+TT genotype was observed to be associated with decreased RIF prevalence (adjusted odds ratio=0.616; 95% CI, 0.386-0.982; P=0.042). Genotype combination analysis for the various miRNA polymorphisms revealed that the DROSHA TC genotype exhibited a highly significant negative association with RIF prevalence when combined with the RAN CT genotype (adjusted odds ratio=0.314; 95% CI, 0.147-0.673; P=0.003; false discovery rate-adjusted P=0.023). The present study revealed an association between the DROSHA rs10719 and RAN rs14035 3'UTR polymorphisms and decreased risk of RIF in Korean women, which suggests that these gene polymorphisms could represent potential markers for predicting RIF risk.

Association of miR-27aA>G, miR-423C>a, miR-449bA>G, and miR-604A>G Polymorphisms with Risk of Recurrent Implantation Failure.

Recurrent implantation failure (RIF) is defined when pregnancy failure occurs after two consecutive in vitro fertilization-embryo transfers to the endometrium using at least four high-quality embryos in women. MicroRNAs are well-known function modulators and are involved in many diseases. Recently, studies on microRNA and recurrent pregnancy loss (RPL) have been actively carried out; however, single nucleotide polymorphisms of miRNA in RPL are not well known. Therefore, we set the aim of this study to identify whether polymorphisms in miRNAs that miR-27aA>G, miR-423C>A, miR-449bA>G, and miR-604A>G are risk factors for idiopathic recurrent implantation failure (RIF) in Korean women. Genotyping was assessed with a polymerase chain reaction-restriction fragment length polymorphism assay. We examined polymorphisms in four miRNA genes: miR-27aA>G, miR-423C>A, miR-449bA>G, and miR-604A>G. We found that the miR-27aA>G, miR-449bA>G, and miR-604A>G polymorphisms were significantly associated with a risk of RIF. In addition, the miR-27aA>G and miR-449bA>G polymorphisms were associated with the frequency of implantation failures. Specifically, the miR-449bAG+GG genotype was associated with RIF prevalence (total RIF: adjusted odd ratio [AOR] = 1.584, 95% CI = 1.008-2.490, P = 0.046; IF ≥ 3 group: AOR = 1.747, 95% CI = 1.088-2.803, P = 0.021; IF ≥ 4: AOR = 1.932, 95% CI = 1.122-3.327, P = 0.018). Based on these results, the miR-449b A>G may be a predisposing factor to RIF susceptibility. However, the mechanism underlying the function of miR-449b A>G in RIF remains to be determined and further studies are needed to improve understanding of the roles of miR-449b A>G, using a larger and more heterogeneous cohort.

Genetic polymorphisms of the cobalamin transport system are associated with idiopathic recurrent implantation failure.

Vitamin B12 (cobalamin, Cbl) plays a role in the recycling of folate, which is important in pregnancy. Transcobalamin II (TCN2) and transcobalamin receptor (TCblR) proteins are involved in the cellular uptake of Cbl. TCN2 binds Cbl in the plasma, and TCblR binds TCN2-Cbl at the cell surface. Therefore, we investigated the potential association between polymorphisms in Cbl transport proteins, TCN2 and TCblR, and recurrent implantation failure (RIF) susceptibility. The genotypes of TCN2 67A>G, TCN2 776C>G, and TCblR 1104C>T were determined for RIF patients and healthy controls using a polymerase chain reaction restriction fragment length polymorphism assay. Additionally, statistical analysis was performed to compare the genotype frequencies between RIF patients and controls. The TCN2 67 polymorphism AG type was associated with RIF risk. Some allele combinations that contained the TCN2 67 polymorphism G allele were associated with increased RIF risk, whereas other allele combinations that contained the TCblR 1104 polymorphism T alleles were associated with decreased RIF risk. In genotype combination analysis, two combinations containing the TCN2 67 polymorphism AG type were associated with RIF risk. Our study showed that the polymorphisms of TCN2 and TCblR are associated with RIF and are potential genetic predisposing factors for RIF among Korean women. Additionally, our findings support a potential role for TCN2 and TCblR in RIF among Korean women. However, further studies are required to investigate the role of the polymorphisms in those proteins and RIF because the roles of the TCN2 and TCblR polymorphisms in RIF are not clear.