Thrombophilic gene polymorphisms and recurrent pregnancy loss: a systematic review and meta-analysis

PURPOSE

Recurrent pregnancy loss (RPL) is affecting 1-4% of women who conceive approximately, and no cause could be found in more than 50% of women suffering from RPL. Inherited thrombophilias have got increasing attention in women with unexplained RPL, so we aim to explore the relationship among these most common thrombophilic polymorphisms and RPL through a literature review and meta-analysis.

METHODS

Observational studies from PubMed, Embase, Cochrane, and Web of Science from 1997 to 7 April 2022 were searched. For each genetic variant, a fixed or random-effect model was used according to the heterogeneity test to calculate pooled ORs and 95% CIs for both dominant and recessive genetic models. Egger's line regression test was used to assess publication bias. The quality of the included articles was assessed by the Newcastle Ottawa scale.

RESULTS

A total of 124 articles comprising 17,278 RPL patients and 16,021 controls were included. Results showed that hyperhomocysteinemia (MTHFR) C677T (dominant model: OR, 1.43; 95% CI, 1.25-1.64; recessive model: OR, 1.60; 95% CI, 1.36-1.87), MTHFR A1298C (dominant model: OR, 1.66; 95% CI, 1.26-2.18; recessive model: OR, 1.79; 95% CI, 1.42-2.26), PAI-1 4G/5G (dominant model: OR, 1.67; 95% CI, 1.36-2.06; recessive model: OR, 1.80; 95% CI, 1.39-2.32), angiotensin-converting enzyme I/D (OR, 1.23; 95% CI, 1.00-1.53), Factor XIII V34L (OR, 1.38; 95% CI, 1.02-1.87), and β-fibrinogen-455G/A (OR, 1.60; 95% CI, 1.02-2.51) were significantly associated with RPL.

CONCLUSION

This study provides potentially useful clinical markers to evaluate the risk of RPL or to help unexplained RPL patients identify possible causes, which may allow for targeted treatment.

H1299R Variant in Factor V and Recurrent Pregnancy Loss: A Systematic Review and Meta-Analysis Protocol

Recurrent pregnancy loss (RPL) is defined as the loss of two or more pregnancies, affecting approximately 1 to 3% of women worldwide. Scientific data highlight a possible correlation between thrombophilic genetic variants and RPL. H1299R variant in the factor V gene would lead to an increased thrombotic risk associated with frequent miscarriages. However, the data are often conflicting, making this an interesting question for further investigations by evaluating genotype-phenotype correlations to improve the clinical management and genetic counseling of couples. A systematic review and meta-analysis will follow the preferred reporting elements for systematic review and meta-analysis protocols (PRISMA-P). The Pubmed (MEDLINE) and Embase (OVID) databases will be explored to identify suitable articles based on inclusion and exclusion criteria. Inclusion criteria are: (a) H1299R genotyping with clear data reported, referred to as Heterozygous (Het) and/or Homozygous (Hom); (b) articles written in English; (c) analyses of only RPL female patients having at least two or more previous pregnancy losses and compared with a control group. This analysis will present selected scientific evidence, addressing the questions concerning the association between the H1299R variant and RPL, hoping to clarify this still unresolved issue. PROSPERO registration number: CRD42022330077.

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.

Thrombophilia and Recurrent Pregnancy Loss: The Enigma Continues

Background

Thrombophilic gene polymorphism is known to be a risk factor for recurrent pregnancy loss (RPL), but few studies have confirmed a possible role of thrombophilic genes polymorphism in RPL risk. This study was conducted to understand the relationship of the mutations of some thrombophilia-associated gene polymorphism (heterozygous/homozygous) with RPL. We compared patients with 2 abortions to patients with 3 or more abortions among Turkish women.

Material/Methods

In this study, patients previously diagnosed with habitual abortus at Obstetrics and Gynecology outpatient clinics in Turkey between 2012 and 2016 were included. In their peripheral blood, we detected factor V Leiden H1299R, prothrombin G20210A, MTHFR C677T, MTHFR A1298C, PAI-1 4G/5G, and PAI-1 4G/4G gene mutations.

Results

In this study, we have observed statistically meaningful data (P<0.01) related to the relationship between RPL and thrombophilia-associated gene polymorphisms such as heterozygous factor V Leiden H1299R, heterozygous prothrombin G20210A, PAI-1 4G/5G, and PAI-1 4G/4G.

Conclusions

We found that diagnosis of thrombophilic genes polymorphism is useful to determine the causes of RPL, recognizing that this multifactorial disease can also be influenced by various acquired factors, including reproduction-associated risk factors and prolonged immobilization.

Association of Plasminogen Activator Inhibitor-1 Gene Polymorphisms and Methylene Tetrahydrofolate Reductase Polymorphisms with Spontaneous Miscarriages

AIM

The objective of this study was to investigate a possible correlation between the plasminogen activator inhibitor-1 (PAI-1) and methylene tetrahydrofolate reductase (MTHFR) polymorphisms and unexplained spontaneous miscarriages (SM).

MATERIALS AND METHODS

PAI-1 polymorphisms were evaluated in 150 women with pregnancy in their history. One hundred women with a history of SM formed the study group and 50 women with normal pregnancies served as the control group. Also, the combination of PAI-1 and MTHFR polymorphisms were evaluated in 138 women out of a total of 150, which included 92 women with SM in their history compared to 46 women in the control group. For statistical analysis, χ2 test, Phi, and Cramer V tests were used; p < 0.05 was taken as a statistically significant result.

RESULTS

Our findings show: (a) the correlation between SM and PAI-1 mutations reaches statistical significance (p = 0.026); (b) there was a statistically significant difference between heterozygous PAI-1 in women with only 1 SM compared to the control group (p = 0.047); (c) the comparison of combinations of both mutations, PAI-1 and MTHFR, with the control group demonstrates statistical significance in favor of women with SM and both mutations (p = 0.022).

CONCLUSION

PAI-1 and MTHFR polymorphisms may play an important role in pregnancy complications because heterozygous PAI-1 mutations and a combination of both PAI-1 and MTHFR mutations might contribute to SM.

Association of Methylenetetrahydrofolate Reductase C677T and A1298C Gene Polymorphisms With Recurrent Pregnancy Loss in Syrian Women

C677T polymorphism of the methylenetetrahydrofolate reductase ( MTHFR) gene was a risk factor for recurrent pregnancy loss (RPL), but few studies have confirmed a possible role of MTHFR A1298C polymorphism in RPL risk. This study was carried out to determine the influence of the MTHFR gene polymorphisms in RPL Syrian women. A case-control study was performed on 2 groups (106 healthy and 100 RPL women). The frequency of the MTHFR gene polymorphisms was determined by polymerase chain reaction based on restriction fragment length gene polymorphism. In the RPL group, the genotype frequencies of MTHFR C677T were CC (41%), CT (41%), and TT (18%), and in the control group, the frequencies were CC (62.2%), CT (36.7%), and TT (1%). Statistical analysis showed a homozygous TT genotype and T allele were significantly different in the RPL group ( P = .000003 and P = .000019, respectively). The genotype frequencies of MTHFR A1298C were AA (53%), AC (44%), and CC (8%) in the RPL group, whereas in the control group, these were AA (61.3%), AC (37.8%), and CC (1%). A significant difference in the CC genotype and C allelic frequencies in the RPL women was observed ( P = .014 and P = .064, respectively). The patients having compound heterozygous (677 CT/1298AC) were associated with an estimated 4.86-fold increase in risk of pregnancy loss compared to individuals with a wild type ( P = .012). Our findings indicate that RPL women with homozygous genotype for (C677T and A1298C) either alone or compound heterozygous genotypes have a high risk of pregnancy loss in Syrian women.

Inherited thrombophilia profile in patients with recurrent miscarriages: Experience from a tertiary care center in north India

The cause of recurrent miscarriage (RM) remains unexplained in approximately 30% to 50% cases. The association of inherited thrombotic factors and RM patients has not been documented from the northern part of India. A total of 40 patients had been investigated for inherited thrombophilia workup (protein C, protein S [PS], antithrombin III, and factor V Leiden [FVL] mutation) over a period of 10 years (2005 to 2014). RM patients were divided in to three groups. Group I (only 1st trimester loss), group II (only 2nd and 3rd trimester), and group III (mixed). Each group comprised of the following numbers of patients respectively: I, 24; II, 2; III, 14. Heterozygous FVL mutation was found in 10% (4/40) cases. PS deficiency was detected in 2.7% (1/37) cases. In the present study FVL and PS were seems to be associated with a subset of patients however further studies with larger numbers of patients are recommended for better evaluation.

Factors contributing to APC-resistance in women with recurrent spontaneous miscarriages: Indian perspective

Phenotypic resistance to APC is a complex mechanism associated with increased risk of venous thrombosis in women with recurrent spontaneous abortions. The primary aim of this prospective case control study was to find out the frequencies of different congenital and acquired thrombophilic factors predisposing to APC resistance and to evaluate the strength of their association with recurrent pregnancy losses. FV Leiden accounted for around 40% of all APCR positive patients and the difference in the group frequencies compared with controls, was found to be statistically significant (p=0.001). 18.33% (11/60) FV Leiden-negative APC-resistant patients had

FVIII

c values exceeding 95th percentile of the control population (145IU/dL), as compared to 3% in the control group (p=0.001). Mean FVIII level in control subjects was 118±14.0IUdL(-), compared with 127.7±31.2IUdL(-) in the patient group (p=0.009). Apart from FVIII, only the anti-phospholipid antibodies showed a statistically significant association with APCR phenotype (p=0.028), unlike other thrombophilic factors such as Protein C, Protein S, FV levels, HR2 haplotype or other rarer FV variants. The strong positive association of FVL mutation, anti-phospholipid antibodies and elevated FVIII levels with APCR phenotype calls for incorporating them as first line investigations in patients with recurrent spontaneous miscarriages with APCR positivity.

Ethnic differences in the association of thrombophilic polymorphisms with obstetric complications in Slovak and Roma (Gypsy) populations

AIMS

Hereditary as well as acquired thrombophilia is associated with a higher incidence of severe obstetric complications such as preeclampsia, spontaneous pregnancy loss, placental abruption, and fetal growth retardation. The aim of our study was to examine the association of selected thrombophilic polymorphisms (factor V Leiden, MTHFR C677T, and MTHFR A1298C) with pregnancy complications in the Slovak majority population and the Roma (Gypsy) ethnic population. The study included 354 women; 120 patients and 105 controls from the Slovak majority population, 50 patients and 79 controls from the Slovak Roma population. Genotyping was performed by the real-time polymerase chain reaction method using TaqMan(®) MGB probes.

RESULTS

A statistically significant higher frequency of factor V Leiden (p=0.001, odds ratio [OR]=5.9) and MTHFR C677T polymorphism (p=0.011, OR=1.7) was observed in the Slovak majority patient group compared to the control group. The incidence of MTHFR A1298C polymorphism between patients and controls did not differ significantly. None of the three polymorphisms studied was in association with pregnancy complications in the group of Roma women.

CONCLUSIONS

Our study has confirmed the variable distribution of selected thrombophilic polymorphisms in different ethnic groups as well as their various effects on the clinical phenotype.

Prevalence of thromogenic gene mutations in women with recurrent miscarriage: A retrospective study of 1,507 patients

Objective

Thromogenic gene mutations has been thought to be associated with recurrent pregnancy loss in women in Turkey. The aim of this study was to investigate the prevalence of thromogenic gene mutations such as factor V Leiden (FVL, G1691T), prothrombin (G20210A), and the methylene tetrahydrofolate reductase (MTHFR, C677T) mutation in women with recurrent pregnancy loss.

Methods

This descriptive study was carried out in the Department of Obstetrics and Gynaecology, Harran University School of Medicine, and included a total of 1,507 women with histories of recurrent pregnancy loss between January 2010 and June 2013. The mutations were assessed by using the polymerase chain reaction.

Results

The homozygous mutation frequencies of FVL, prothrombin, and MTHFR were found to be 3 (0.20%), 0 and 125 (8.29%), and the heterozygous mutation frequencies were 83 (5.51%), 61 (4.05%), and 612 (40.61%), respectively. Among the 86 FVL mutation patients, 38 also had accompanying prothrombin and MTHFR mutations.

Conclusion

Since the homozygous forms of the FVL-prothrombin gene mutations have low incidences and MTHFR mutation is similar to a healthy population, preconceptional thromogenic gene mutations screening seems to be controversial.

Evaluation of chromosomal abnormalities and common trombophilic mutations in cases with recurrent miscarriage

BACKGROUND

Recurrent miscarriage (RM) is a frequent obstetric problem. Its' pathophysiology is poorly understood. Infections, genetic, endocrine, anatomic and immunologic problems have been suggested as causes for RM.

OBJECTIVE

To evaluate the frequency of chromosomal abnormalities and 3 common thrombophilic mutations in couples with RM.

METHODS

A retrospective data collection was performed for the results of the cytogenetic analysis of the couples and Methylenetetrahydrofolate Reductase (MTHFR) C677T, Factor V Leiden (FVL) G1691A and Prothrombin (PTm) G20210A mutations of the mother in 142 couples suffering from RM.

RESULTS

Prevalence of FVL, MTHFR, and PTm gene mutations were similar between cases shaving 2 or ≥3 abortions (P=0.528; P=0.233; P=0.375). In patients with FVL, MTHFR and PTm gene mutations, the OR's of having ≥3 abortions when compared to having 2 abortions were 1.515 (95% CI: 0.414-5.552), 0.573 (95% CI: 0.228-1.441), and 2.848 (95% CI: 0.355-22.871). All cases with PTm mutation had ≥3 abortions and all abortions occurred between 6-8 gestational weeks.

CONCLUSION

Chromosomal abnormalities and thrombophilic mutations (especially PTm) seem to have an important role in RM. Additional larger studies involving investigation of more genes that may have a role in pregnancy are needed to assess this association.

Can Factor V Leiden and prothrombin G20210A testing in women with recurrent pregnancy loss result in improved pregnancy outcomes?: Results from a targeted evidence-based review

Women with recurrent pregnancy loss are offered Factor V Leiden (F5) and/or prothrombin G20210A (F2) testing to identify candidates for anticoagulation to improve outcomes. A systematic literature review was performed to estimate test performance, effect sizes, and treatment effectiveness. Electronic searches were performed through April 2011, with review of references from included articles. English-language studies addressed analytic validity, clinical validity, and/or clinical utility and satisfied predefined inclusion criteria. Adequate evidence showed high analytic sensitivity and specificity for F5 and F2 testing. Evidence for clinical validity was adequate. The summary odds ratio for association of recurrent pregnancy loss with F5 in case-controlled studies was 2.02 (95% confidence interval, 1.60-2.55), with moderate heterogeneity and suggestion of publication bias. Longitudinal studies in women with recurrent pregnancy loss or unselected cohorts showed F5 carriers were more likely to have a subsequent loss than noncarriers (odds ratios: 1.93 and 2.03, respectively). Results for F2 testing were similar. For clinical utility, evidence was adequate that anticoagulation treatments were ineffective (except in antiphospholipid antibody syndrome) and had treatment-associated harms. The certainty of evidence is moderate (high, moderate, and low) that anticoagulation of women with recurrent pregnancy loss and F5/F2 variants would currently lead to net harms.