Association of anticardiolipin antibody and C677T in methylenetetrahydrofolate reductase mutation in women with recurrent spontaneous abortions: a new path to thrombophilia?

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.

Therapeutic Implications of Inherited Thrombophilia in Pregnancy

BACKGROUND

Inherited (hereditary) thrombophilia is a genetic disorder that affects coagulation, being responsible for more than 60% of idiopathic (spontaneous or unprovoked) thromboembolic events. Association of inherited thrombophilia with pregnancy increases the risk of thromboembolic disease, and it may be related to many complications, such as preeclampsia, recurrent miscarriage intrauterine growth restriction, early detachment of placenta, and prematurity.

AREAS OF UNCERTAINTY

Interpretation of a positive test for thrombophilia in pregnant women is difficult because they have many natural changes in the coagulation system. Genetic diagnosis of thrombophilia, after a thrombotic event or during a pregnancy complication, has a major importance, not only to define its etiology but also to determine the duration of anticoagulant treatment and risk stratification for prophylaxis treatment.

DATA SOURCES

Literature search was performed using electronic database (PubMed) between April 1981 and November 2018. We used different keywords and MeSH terms to generate the most relevant results related to the inherited thrombophilia and its impact on pregnancy.

RESULTS

Screening for inherited thrombophilia in young women is recommended in case of personal history of venous thromboembolism, first-degree relatives with a history of high-risk thrombophilia, or personal history of second-trimester miscarriage. Decision to recommend thromboprophylaxis with anticoagulant treatment in pregnant women with inherited thrombophilia is determined by history of venous thromboembolism, type and associated risk of inherited thrombophilia, and presence of additional risk factors. Low-molecular-weight heparins are the preferred agents for prophylaxis in pregnancy, while the doses vary depending on thrombophilia type, personal history, and associated risk factors.

CONCLUSIONS

Association between 2 procoagulant conditions, inherited thrombophilia and pregnancy, has an important impact for the mother and fetus. This review will summarize the impact of each inherited prothrombotic factor on cardiovascular and pregnancy outcomes and will discuss the role of anticoagulation treatment for women diagnosed with inherited thrombophilia.

Thrombophilic Mutations and Polymorphisms, Alone or in Combination, and Recurrent Spontaneous Abortion

Generally, recurrent spontaneous abortions (RSAs) have no identifiable cause; yet, vascular alterations during pregnancy may be associated with pregnancy loss. Therefore, we evaluated the association between thrombophilic mutations and RSAs. This case–control study was conducted in 112 patients who had RSAs and 98 health control women. Genomic DNA was extracted from whole blood, and polymorphism genotyping was conducted using polymerase chain reaction. The following 6 genetic variants were analyzed: factor V Leiden, prothrombin mutation, methylenetetrahydrofolate reductase C677T and A1298C, plasminogen activator inhibitor type 1 (4G>5G), and factor XIII G103T (V34L). No correlations were found in any of the investigated polymorphisms. Moreover, 35.0% of cases and 25.5% of controls had at least 2 mutations in combination, and 4.8% of cases and 5.1% of controls had 3, but these combinations were not associated with additional risk. In conclusion, we found no association between the polymorphisms studied and the occurrence of RSAs.

Association study between methylenetetrahydrofolate reductase polymorphisms and unexplained recurrent pregnancy loss: a meta-analysis

BACKGROUND

Recurrent pregnancy loss is an important clinical problem. Recently, high-level homocysteine in blood has been considered as a possible cause. Genetic polymorphisms in methylenetetrahydrofolate reductase (MTHFR) have been proved to be the common hereditary factors of high-level homocysteine. The association between MTHFR polymorphisms and unexplained recurrent pregnancy loss (URPL) has been reported but with controversial results. The purpose of present study is to collect and analyze published available data, and evaluate the association between MTHFR polymorphisms and URPL.

METHODS

A meta-analysis was performed to examine the association between MTHFR polymorphisms (C677T and A1298C) and URPL. Odds ratio (OR) and its 95% confidence interval (CI) were used in each study of genotype and allele contrast.

RESULT(S)

MTHFR C677T: The analysis included 3559 URPL cases and 5097 healthy controls. Overall random-effects odds ratios (ORs) were 1.68 (95% CI, 1.32-2.13; P<0.0001) for TT versus total genotypes, 1.35 (95% CI, 1.04-1.76; P=0.0224) for TT and CT genotype combined versus total genotypes and 1.34 (95%CI, 1.13-1.58; P<0.0001) for T versus total alleles. Although significant heterogeneity was found in C677T, it became weaker in the East Asian subgroup and the mixed subgroup when separated by ethnic subgroups. The results showed significant association between MTHFR C677T and URPL in the East Asian subgroup (ORs 2.11 for TT versus total genotype (P=0.0004) and 1.53 for T versus total alleles (P<0.0001)) and in the mixed subgroup (ORs 3.47 for TT versus total genotypes (P<0.0001) and 1.80 for T versus total alleles (P<0.027)), but not in Caucasian subgroup. MTHFR A1298C: The study involved 1163 URPL cases and 1061 healthy controls. Overall random-effects odds ratios (ORs) were 1.37 (95% CI, 0.71-2.67; P=0.3456) for CC versus total genotypes, 1.16 (95%CI, 0.98-1.38; P=0.0833) for CC+AC versus total genotypes and 1.04 (95%CI, 0.84-1.29; P=0.7112) for C versus total alleles. No significant association between MTHFR A1298C polymorphism and URPL was found.

CONCLUSIONS

These results indicate a significant association between MTHFR C677T mutation and URPL in the East Asian subgroup and mixed subgroup, but no significance in MTHFR A1298C mutation.

Recurrent Abortions in Asian Indians: No Role of Factor V Leiden Hong Kong/Cambridge Mutation and MTHFR Polymorphism

Recurrent fetal loss is a frequent health problem. Data accumulated over the past few years have suggested a possible correlation between thrombophilia and fetal loss. Although a clear association has been established between fetal loss and certain thrombophilic states, such as antiphospholipid antibody syndromes, antithrombin deficiency, and combined defects, reports on the prevalence of inherited prothrombotic defects such as factor V Leiden mutation and methylene tetrahydrofolate reductase C677T polymorphism in fetal loss are contradictory. The prevalence of these 2 mutations in Asian Indians with recurrent fetal loss has not yet been studied. In light of this, the present study looked at the prevalence of these mutations in 85 patients with spontaneous recurrent abortion and 31 controls. The authors did not find any significant role of these mutations in the development of recurrent abortion.

Methylenetetrahydrofolate reductase C677T polymorphism and the risk of unexplained recurrent pregnancy loss: a meta-analysis

OBJECTIVE

To investigate the association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of unexplained recurrent pregnancy loss (URPL).

DESIGN

Meta-analysis of published case-control studies of the MTHFR C677T variant and URPL risk.

SETTING

A research institution in China.

PATIENT(S)

Women with URPL.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Odds ratios (ORs) and 95% confidence intervals (CIs) for TT versus CC genotype, CT versus CC genotype, TT versus CT and CC genotype combined, and for T versus C allele.

RESULT(S)

Twenty-six studies with 2120 URPL cases and 2949 controls were included. Overall random-effects ORs of 1.49 (95% CI, 1.12-2.00) for TT versus CC genotype, 1.40 (95% CI, 1.11-1.77) for TT versus CT and CC genotype combined, and 1.21 (95%CI, 1.04-1.40) for T versus C allele were found. Stratified analysis showed that significant strong associations between MTHFR C677T polymorphism and URPL were present only in the five Chinese studies (OR = 2.96 for TT versus CC genotype; OR = 2.30 for TT versus CT+CC genotype; OR = 1.73 for T versus C allele), but not in any other studies, including the studies conducted in the European countries.

CONCLUSION(S)

The MTHFR C677T mutation is not a genetic risk factor for URPL except in a Chinese population.