Investigation of the Annexin A5 M2 haplotype in 500 white European couples who have experienced recurrent spontaneous abortion

ANXA5 and VEGFA Gene Variants in Women with Early Pregnancy Losses from North Macedonia

Early pregnancy loss (EPL) is the most common pregnancy complication, found in approximately 15% of all clinically recognized pregnancy complications. Up to date, various maternal as well as fetal factors are reported as a cause of EPLs. However, in approximately 50% of EPL cases, the exact cause is not clearly identified and these cases are referred as idiopathic. The aim of our study was to examine the association of four distinct variants in the ANXA5 gene and two variants within the VEGFA gene in a cohort of women with EPLs from North Macedonia. This group was compared to a control group of women matched by ethnic background without pregnancy loss and at least one live birth. We also aimed to establish an effective and cost-efficient method for their detection based on multiplex single-base extension. Among 190 women experiencing EPLs, and 190 samples from women without a history of pregnancy loss (control group), our results demonstrated a statistically significant prevalence of heterozygotes for the M2/ANXA5 haplotype in women with EPLs, compared to the control group (p=0.0006). In the analyses comparing genotypic frequencies for the variants in the VEGFA gene, higher frequencies were generally observed among women experiencing EPLs, however without statistical significance. Our study aligns with multiple studies showing that M2 and M1 ANXA5 haplotypes are more prevalent in patients with pregnancy loss and presents an affordable genotyping technique for the specific ANXA5 and VEGFA variants.

Use of anticoagulants to improve pregnancy outcomes in couples positive for M2 haplotype: A systematic review

BACKGROUND

Placental mediated pregnancy complications (PMPC) are common, often recurring, and pose a significant health risk to mother and fetus. Evidence suggests that the hypercoagulable state associated with many PMPC, could reflect reduced expression of Annexin 5 (ANXA5), a naturally occurring anticoagulant protein in placental tissue. The ANXA5 M2 haplotype is a genetic variant, which results in reduced expression of ANXA5 protein. M2 haplotype carrier couples may therefore be at increased risk of PMPC. Evidence regarding the effectiveness of anticoagulation to prevent PMPC is inconsistent. Furthermore, studies have not selected or stratified for M2 haplotype carriers, in whom there is a predisposition to hypercoagulability, to assess the effectiveness of anticoagulation, which may vary from those without the M2 haplotype.

OBJECTIVES AND RATIONALE

The aim of this study was to systematically review the current evidence to assess whether anticoagulant treatment improves pregnancy outcomes in couples positive for M2 haplotype.

SEARCH METHODS

The review was registered on PROSPERO (CRD42022343943). A comprehensive literature search was performed using MEDLINE, Embase and Cochrane collaboration databases from inception to January 2023. Two reviewers assessed the articles for eligibility and extracted the data simultaneously. Primary outcome was successful pregnancy and live birth. Secondary outcomes included PMPC (implantation failure, miscarriage, pre-eclampsia, preterm birth and fetal growth restriction).

OUTCOMES

From a pool of 410 references, 10 were selected for full text review, of which three studies (a post hoc analysis of a randomised controlled trial, cohort study and a case report) were included in this review. Included studies comprised of 223 individuals, 129 of whom who received anticoagulation treatment after testing positive for M2 haplotype. The studies collectively showed an improvement in pregnancy outcomes in M2 haplotype positive individuals however, given the heterogeneity of studies, it was not possible to conduct a meta-analysis and draw firm conclusions.

WIDER IMPLICATIONS

Current evidence is limited, such that the value of screening couples for the M2 haplotype to select or stratify for treatment with prophylactic anticoagulation remains unknown. Thus, further studies including well designed, large, multi-centre randomised controlled trials are required to assess whether anticoagulation treatment will be effective in improving pregnancy outcomes in M2 haplotype couples.

Association of male factors with recurrent pregnancy loss

The role of male factors in recurrent pregnancy loss (RPL) is receiving increased attention since sperm quantity and quality, male genetic mutations, as well as epigenetic modifications, have all been associated with RPL. A growing number of studies have been published on the relationship between male factors and RPL; however, these reports are limited due to small sample sizes, inconsistent inclusion criteria, and detection methods. Herein, we investigate the effects of several male factors on RPL from a genetic and non-genetic perspective to aid clinicians in determining the etiology and optimal treatment strategy for patients with RPL.

Research progress on ANXA5 in recurrent pregnancy loss

The incidence of recurrent pregnancy loss (RPL) in fertile women ranges from 1% to 5%, of which about 50% of them are due to unknown causes. The possible pathogenesis of RPL is an urgent problem to be solved in the clinical. Mutations or polymorphisms of certain genes in the coagulation mechanism are associated with susceptibility to thrombotic diseases and are one of the main reasons for the occurrence of RPL. Among them, the ANXA5 gene was newly studied and some single nucleotide polymorphisms (SNPs) in the promoter region of ANXA5 have been reported to be associated with RPL in multiple races. In this review, we summarized the research progress on the correlation between the SNPs in ANXA5 and RPL, hoping to provide some valuable guidance for the future studies.

A novel test for annexin A5 M2 haplotyping in in vitro fertilization patients and preimplantation embryos

OBJECTIVE

To develop a test for evaluating the annexin A5 M2 haplotype in in vitro fertilization patients and preimplantation embryos.

DESIGN

Test performance was measured by comparing Sanger sequencing of parental blood DNA and quantitative real-time polymerase chain reaction (qPCR) of saliva DNA, 3 fibroblast cell line 7-cell aliquots and their corresponding purified DNA, 123 trophectoderm biopsy samples, and DNA isolated from 1 embryonic stem cell line along with the Mendelian inheritance expectations, embryo Sanger sequencing, and single-nucleotide polymorphism (SNP) microarray-based linkage analysis.

SETTING

Preimplantation genetic testing laboratory research on IVF patient and embryo DNA.

PATIENT(S)

An assay was developed for the detection of the M2 haplotype on saliva samples of 6 in vitro fertilization patients. In addition, 13 patients who underwent preimplantation genetic testing with data on parental and embryo biopsy DNA available for research use were evaluated.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The concordance rates between Sanger sequencing, SNP array-based linkage analysis, and Mendelian inheritance expectations with qPCR.

RESULT(S)

The concordance rate between Sanger sequencing and qPCR was 100% on parental blood DNA and saliva DNA. The sample concordance rate between all replicates of 7-cell aliquots was 100%. The sample concordance rate between 3 cell lines used to prepare 7-cell aliquots and purified genomic DNA was 100%. The concordance rate between qPCR and Sanger sequencing results from a single trophectoderm biopsy and isolated embryonic stem cell line was 100%. The concordance rate of trophectoderm biopsy qPCR results and expectations from Mendelian inheritance rules was 97%; however, when SNP array-based linkage analysis was included, the concordance rate reached 100%.

CONCLUSION(S)

This study resulted in the development of a convenient saliva collection method and qPCR-based genotyping method to screen for the M2 haplotype. In addition, a novel method for testing preimplantation embryos has been established, providing an alternative to the use of low molecular weight heparin, through selection of embryos without the M2 haplotype.

The relevance of ANXA5 genetic variants on male fertility

PURPOSE

To investigate the effect of the anticoagulation factor annexin A5 on male fertility and to provide perspective on the influence of members of the coagulation cascade on fertility.

METHODS

Patients with normozoospermia and with unexplained severe oligozoospermia were retrospectively selected and their genomic DNA sequenced for the promoter region of ANXA5. The genotypes proportions and the odds ratio for carriership of the haplotype M2 were compared between the groups and population control. The clinical data used were gathered from parameters determined during routine clinical assessment and were compared between carriers and non-carriers within the patient groups.

RESULTS

The carrier rates for the haplotype M2/ANXA5 were of 25.73%, 20.81%, and 15.3% in the severe oligozoospermic, the normozoospermic, and the general population control groups, respectively. The OR between patients groups was of 1.31 (95% CI 0.88 to 1.96 p = 0.176). Oligozoospermic and normozoospermic patients compared with the control group had an OR of 1.9 (95% CI 1.33 to 2.73 p < 0.001) and 1.45 (95% CI 0.99 to 2.10 p = 0.054) respectively. The clinical parameters that differed between the carriers and non-carriers of the haplotype M2/ANXA5 were prolactin, α-glucosidase, and fructose. The differences were only statistically significant in the normozoospermic group.

CONCLUSIONS

Athough the infertile patient groups had a higher prevalence of promoter variants, we could not demonstrate any biologically relevant effect of lower levels of annexin A5 on most male fertility parameters. A deficiency in an anticoagulation factor does not seem to impact male fertility.

Association between M2/ANXA5 haplotype and repeated pregnancy loss: a meta-analysis

OBJECTIVE

To ascertain the magnitude and precision of the association between M2/ANXA5 haplotype and repeated pregnancy loss (RPL).

DESIGN

Meta-analysis of odds ratios.

SETTING

Not applicable.

PATIENT(S)

Subjects were women with RPL and their partners.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

The association between M2/ANXA5 haplotype and RPL was evaluated in a meta-analysis of odds ratios. We further scrutinized this association according to [1] the sequence of miscarriages, [2] the number of consecutive losses, [3] the extent of excluding other pathologies of RPL, and [4] the timing of fetal loss.

RESULT(S)

Fourteen individual studies (n = 4,664 subjects) were included in this meta-analysis. The results show that women with the M2/ANXA5 haplotype have 1.54 times (95% confidence interval, 1.08-2.20) the odds of having associated RPL compared with women with the normal haplotype, regardless of consecutive or nonconsecutive pregnancy losses. Acknowledging the clinical heterogeneity among the studies, this significant association comes with a caveat that the lower bound of the confidence interval is close to unity. In couple populations (n = 2,449), M2/ANXA5 haplotype subjects have an odds ratio of 1.48 (95% confidence interval, 1.14-1.91) of experiencing RPL, which suggests contributions from paternal M2/ANXA5 carriers in RPL.

CONCLUSION(S)

This meta-analysis ascertains that women with the M2/ANXA5 haplotype have a higher risk of experiencing RPL, especially consecutive early idiopathic RPL. Male partners with the M2/ANXA5 haplotype partly contribute to this risk. Hence, screening for the M2/ANXA5 haplotype as a panel of laboratory investigations for RPL is recommended.

Correlation of single nucleotide polymorphisms in the promoter region of the ANXA5 (annexin A5) gene with recurrent miscarriages in women of Greek origin

Background: Recent findings show that a number of single nucleotide polymorphisms (SNPs) within the promoter region of the annexin A5-gene (ANXA5) reduce the expression of the reporter gene and so they display a significant association with recurrent pregnancy loss (RPL).Objective: The objective of the present study aimed to address the contribution of ANXA5 M2 haplotype consisting of four minor alleles: (SNP1: (-)467G > A, SNP2: (-)448A > C, SNP3: (-)422T > C, and SNP4: (-)373G > A) in the occurrence of recurrent pregnancy losses in the Greek population, and the role of further two minor alleles: SNP5: (-)302 T > G and SNP6: (-)1C > T as independent risk factors for RPL.Methods: A 752-bp genomic region of ANXA5 promoter was amplified by PCR using specific primers. Genotypic analysis by Sanger sequencing was performed for these six SNPs (minor alleles) in the promoter region of ANXA5 gene, in 100 (100) Greek women with recurrent miscarriages (median =3) and 70 (70) fertile controls. Statistical analysis was done using the SAS 9.3 for Windows (SAS Institute Inc, NC, USA) and SPSS packages for Windows (C.DiMaggio 2013, SAS Institute 2014).Results: This case-control study revealed that there is no significantly increased risk of RPL among the M2/ANXA5 haplotype carriers in the Greek population, as there were no statistical differences between the patients with recurrent pregnancy losses and the fertile controls (11.5% in RPL cases versus 9.29% in controls, p-value: .6364). There was no difference in SNP5 and SNP6 minor carriership between the two groups. In particular, carriers of SNP5 and SNP6 had an increased risk for RPL state with odds ratio: 1.2472 and 1.3846 respectively, however without statistically significant importance.Conclusion: The M2/ANXA5 haplotype does not differ between RPL patients and controls in the Greek population. Also, it is the first time that SNP5 and SNP6 minor alleles were evaluated extensively in women of European origin with recurrent pregnancy losses (RPL), and they do not seem to be independent risk factors in the occurrence of RPL in the Greek population. Though, this has to be confirmed in further and larger clinical trials with women of European origin.

Micromolar Zinc in Annexin A5 Anticoagulation as a Potential Remedy for RPRGL3-Associated Recurrent Pregnancy Loss

Deficient expression of the placental anticoagulant annexin A5 (ANXA5) has been associated with thrombophilia-related pregnancy complications and ultimately with recurrent pregnancy loss (RPL). Carrier status of M2/ANXA5 ( RPRGL3), common ANXA5 promoter variant, has been identified as genetic cause of reduced ANXA5 levels and proposed as biomarker for successful anticoagulant treatment of RPL women. A murine model of AnxA5 loss of function displayed characteristic placental pathology and fetal loss that was alleviated through anticoagulant intervention. This study identified an alternative means of supplementing anticoagulation, through elevated ANXA5 expression. Physiological micromolar Zn²⁺ stimulated ANXA5 transcription, raising ANXA5 protein expression and surface abundance on BeWo and human umbilical vein endothelial cells (HUVEC), thus resulting in prolonged coagulation times. Zn²-fed AnxA5 functionally deficient pregnant mice showed a trend to increase litter size when primiparous that grew comparable to wild-type progeny in subsequent pregnancies. Elevated AnxA5 signal upon Zn²⁺ treatment was confirmed in murine placentae. Micromolar Zn²⁺ stimulated ANXA5 expression in cell culture directly and alleviated RPL in AnxA5 genetically deficient mice, without notable toxicity effects.

Maternal carriers of the ANXA5 M2 haplotype are exposed to a greater risk for placenta-mediated pregnancy complications

PURPOSE

Annexin A5 (ANXA5) is a protein abundantly expressed in normal placenta where it contributes to the healthy outcome of a pregnancy. Lower ANXA5 levels have been observed in M2/ANXA5 haplotype carrying chorion. Consequently, this study aimed to assess the potential association of M2 maternal carrier status with the risk of recurrent pregnancy loss (RPL), the timing of miscarriages, and other obstetric complications, for the first time in a population from Latin America.

METHODS

This study was designed as a prospective recruitment of RPL patients with post hoc analysis. The distribution of the M2/ANXA5 haplotype was compared between a group of 229 Argentine women with RPL and 100 parous controls, and was further analyzed in subgroups of patients stratified according to the timing of miscarriages and in relation to other obstetric complications.

RESULTS

No significant differences were found in the distribution of M2 haplotype among either RPL patients or the subgroups with embryonic, early fetal, or late fetal losses compared to parous controls. Notwithstanding, maternal M2/ANXA5 was found to be independently associated with a higher risk of suffering intrauterine growth restriction (IUGR) and/or preeclampsia (PE). Simultaneously, the presence of inherited and/or acquired thrombophilia also proved to be an independent risk factor for these.

CONCLUSIONS

The association found between the maternal carriage of the M2/ANXA5 haplotype and an elevated risk of IUGR and/or PE supports the hypothesis that carrier status of this haplotype and the consequently reduced placental ANXA5 expression might be responsible, at least partially, for the onset of these gestational vascular complications.

Assessment of M2/ANXA5 haplotype as a risk factor in couples with placenta-mediated pregnancy complications

PURPOSE

The aim of this study was to confirm the associated M2/ANXA5 carrier risk in women with placenta-mediated pregnancy complications (PMPC) and to test their male partners for such association. Further analysis evaluated the influence of maternal vs. paternal M2 alleles on miscarriage.

METHODS

Two hundred eighty-eight couples with preeclampsia (PE), intrauterine growth restriction (IUGR), or premature birth (PB) were recruited (n = 96 of each phenotype). The prevalence of the M2 haplotype was compared to two control cohorts. They included a group of women with a history of normal pregnancy without gestational pathology (Munich controls, n = 94) and a random population sample (PopGen controls, n = 533).

RESULTS

Significant association of M2 haplotype and pregnancy complications was confirmed for women and for couples, where prevalence was elevated from 15.4 to 23.8% (p < 0.001). Post hoc analyses demonstrated an association for IUGR and PB individually. A strong link between previous miscarriages and M2 carrier status was identified which may explain the predisposition to placental pregnancy complication. M2/ANXA5 appears to be a risk factor for adverse pregnancy outcomes related, but not limited to miscarriages, with similar prevalence in women and their male partners.

CONCLUSION

These findings support the proposed physiological function of ANXA5 as an embryonic anticoagulant that appears deficient in contiguous specter of thrombophilia-related pregnancy complications culminating more frequently in miscarriage in a maternal M2 carrier background.

LMWH in IVF - Biomarkers and benefits

There is biological plausibility that coagulation activation underlies a proportion of in vitro fertilisation IVF failures and recurrent early clinical pregnancy loss (RPL). However, low-molecular-weight heparin (LMWH) use, based upon previous clinical outcome alone, is not effective in preventing RPL. RPL is heterogeneous in mechanism. Identifying those with an underlying thrombotic mechanism would allow stratification for LMWH treatment. Annexin A5 is an anticoagulant protein expressed on the trophoblast surface. The annexin A5 M2 haplotype (ANXA5 M2) is associated with several placenta mediated pregnancy complications (PMPC) and poor IVF outcome. It is transmitted equally by males and females. A pragmatic observational study of IVF couples screened for M2 carriage and treated with LMWH achieved a 37.9% live birth rate, similar to an unscreened and untreated group with fewer adverse risk factors for conception and a better prognosis from assisted conception. This suggests that LMWH may counteract the adverse effects of M2 carriage. Using this biomarker to stratify IVF and PMPC patients for LMWH treatment merits further evaluation.

Genetic analysis of the M2/ANXA5 haplotype as recurrent pregnancy loss predisposition in the Malay population

PURPOSE

The aim of this study was to evaluate a new predisposition factor, M2/ANXA5 (RPRGL3), in recurrent pregnancy loss (RPL) patients of Malay origin, since it was previously known that the prevalence of this condition is relatively high among the Malay population of Malaysia, where conventional hereditary thrombophilia factors have been generally ruled out.

METHODS

A total of 232 women who had experienced ≥2 unexplained RPL and 141 available male partners were recruited, with 360 healthy Malay and 166 parous female controls. Prevalence of M2 carriage and RPL odds ratios were calculated in (a) control and patient groups; (b) clinically defined subgroups in categories of pregnancy loss, primary, secondary, and tertiary; and (c) timing of pregnancy loss in early, ≤15th gestation week and "late" fetal losses, and >15th gestation week subgroups.

RESULTS

Both male and female subjects had similar M2/ANXA5 allele frequencies. The carrier rate of M2/ANXA5 for the general Malay population was 42.2 and 34.9% for parous controls. These carrier rates compared to Malay RPL subjects (52% M2 carriers) resulted in elevated odds ratios (95% confidence interval) of 1.53 (1.1 to 2.1) and 1.97 (1.3 to 3.1) accordingly for early fetal losses. Moreover, exceeding copy numbers of M2/ANXA5 alleles seemed to afflict a greater chance of RPL in couples, especially when both partners were M2 carriers.

CONCLUSION

This study confirmed the proposed role of M2/ANXA5 as embryonic, genetically associated thrombophilia predisposition factor for early RPL among ethnic Malay of Malaysia.

Precision Medicine in Assisted Conception: A Multicenter Observational Treatment Cohort Study of the Annexin A5 M2 Haplotype as a Biomarker for Antithrombotic Treatment to Improve Pregnancy Outcome

BACKGROUND

Pregnancy failure and placenta mediated pregnancy complications affect >25% of pregnancies. Although there is biological plausibility for a procoagulant mechanism underlying some of these events, antithrombotic intervention trials demonstrate limited benefit, possibly through lack of stratification in heterogeneous patient groups. The ANXA5 M2 haplotype is a possible procoagulant biomarker and was tested pragmatically to determine whether this screening and LMWH treatment normalized the outcome for ANXA5 M2 positive couples. This was a pragmatic study that aimed to measure the effectiveness of a testing (for the M2 haplotype) and treatment (LMWH) pathway in routine clinical practice where there is variation between patients. Such a study in couples with fertility problems can inform choices between treatments; it is then the management protocol which is the subject of the investigation, not the individual treatments.

METHODS

Couples (N=77) with one or both partners ANXA5 M2 positive demonstrated association of this haplotype with adverse IVF outcome. A pragmatic, multicenter, prospective cohort study of ANXA5 M2 haplotype screening, and LWMH treatment following embryo transfer (ET) in 103 IVF couples positive for ANXA5 M2 was performed. They were compared with a group of 1000 contemporaneous randomly selected unscreened and untreated couples undergoing assisted conception, from which 103 matched control couples were derived. The primary outcome measure was live birth incidence. Secondary outcomes were results following embryo transfer (ET) and live birth outcome by gender and M2 carriage, and allelic dose influence.

FINDINGS

The tested and treated cohort of ANXA5 M2 carriers achieved a similar live birth rate (37.9%) per ET cycle compared to both the more fertile comparison group (38.5%), and to the 103 matched controls (33.0%). Significantly more treated male carrier only couples had a live birth versus female M2 only (47.7% vs. 25.0% p=0.045).

INTERPRETATION

Pragmatic ANXA5 M5 screening and treatment with LMWH in couples undergoing IVF is associated with similar outcome to couples with more favorable prognostic factors. The difference in live birth outcome for treated male only carrier couples may be consistent with an additional maternal thrombophilic factor that may adversely affect pregnancy, although other mechanisms are possible. This study suggests that LMWH treatment should be started prior to clinical pregnancy.

Annexin A5 haplotype M2 is not a risk factor for recurrent spontaneous abortion in Northern Europe: is there sufficient evidence?

The M2 haplotype of the annexin A5 gene is a well-recognized predisposition factor for recurrent spontaneous abortion (RSA). A recent publication by Nagirnaja et al. (2015) in PLoS One discusses the risk role of the M2 haplotype for RSA in cases compared with controls of North European extraction and arrives at a negative result. As a number of previous and fairly recent studies have supported the proposed involvement of the M2 haplotype in the cause of idiopathic RSA, this commentary aims to highlight problematic issues in the above publication. It is the opinion of the authors that the study by Nagirnaja et al. (2015) does not generate adequate proof of the absence of RSA risk, attributable to carriage of the M2 haplotype.

Thrombophilia and Pregnancy Complications

There is a paucity of strong evidence associated with adverse pregnancy outcomes and thrombophilia in pregnancy. These problems include both early (recurrent miscarriage) and late placental vascular-mediated problems (fetal loss, pre-eclampsia, placental abruption and intra-uterine growth restriction). Due to poor quality case-control and cohort study designs, there is often an increase in the relative risk of these complications associated with thrombophilia, particularly recurrent early pregnancy loss, late fetal loss and pre-eclampsia, but the absolute risk remains very small. It appears that low-molecular weight heparin has other benefits on the placental vascular system besides its anticoagulant properties. Its use is in the context of antiphospholipid syndrome and recurrent pregnancy loss and also in women with implantation failure to improve live birth rates. There is currently no role for low-molecular weight heparin to prevent late placental-mediated complications in patients with inherited thrombophilia and this may be due to small patient numbers in the studies involved in summarising the evidence. There is potential for low-molecular weight heparin to improve pregnancy outcomes in women with prior severe vascular complications of pregnancy such as early-onset intra-uterine growth restriction and pre-eclampsia but further high quality randomised controlled trials are required to answer this question.