The association between 5, 10 - methylenetetrahydrofolate reductase and the risk of unexplained recurrent pregnancy loss in China: A Meta-analysis

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.

Correlation between methylenetetrahydrofolate reductase gene-specific methylation and recurrent spontaneous abortion

OBJECTIVE

To investigate the correlation between methylenetetrahydrofolate reductase (MTHFR) gene-specific methylation and recurrent spontaneous abortion (RSA).

METHODS

A total of 50 RSA patients who visited our hospital were recruited in the study group; 50 multiparous women who underwent physical examinations during the same period were enrolled in the control group. The levels of homocysteine, folic acid, and vitamin B12 and their MTHFR gene polymorphism and specific methylation were measured in both groups. The Logistic regression equation was used to analyze the correlation between MTHFR gene-specific methylation and RSA.

RESULTS

The methylated allele MM was not found in the control group, and the frequency in the study group was 1.19%. The frequency of the MU genotype in the study group 32.93% was higher than that in the control group 12.45%. The frequency of methylated alleles of CC and CT genotypes carrying MTHFR C677T polymorphism in the study group was higher than that in the control group (P < 0.05). There was no significant difference in the TT genotype between the two groups (P > 0.05). Multivariate Logistic regression analysis exhibited that patients with methylated alleles of CC genotype had a risk of RSA increased by 1.167 times, and the risk increased by 2.500 times in patients with methylated alleles of CT genotype (P < 0.05). 83.33% of RSA patients carrying methylated alleles affected hyperhomocysteinemia. In patients with elevated homocysteine levels, the risk of RSA caused by methylated allele was significantly increased by 7.321 times.

CONCLUSION

MTHFR gene-specific methylation can significantly increase the risk of RSA.

Reduced Steroid Synthesis in the Follicular Fluid of MTHFR 677TT Mutation Carriers: Effects of Increased Folic Acid Administration

Objective To compare steroid profiles in the follicular fluid (FF) from women homozygous for the methylenetetrahydrofolate reductase (MTHFR) 677C>T mutation and wildtype controls and to correlate it with the folic acid administration scheme applied at the time of oocyte retrieval. Design Retrospective single center study. Subjects and Methods Infertile patients treated by using assisted reproductive techniques were genotyped routinely for the MTHFR 677C>T mutation. In 2006 they had received folic acid supplementation doses of 400 µg daily per os. This group was designated Group-400 (n = 10). From 2008 onwards, all of our infertility patients received a daily dose of 800 µg folic acid per os. Women from this group were designated Group-800 (n = 28). FF were collected and a panel of steroid hormones (estradiol, estrone, estriol, cortisol, progesterone, 17-OH progesterone, testosterone, androstenedione, aldosterone, DHEA, and DHEA-S) was measured by isotope dilution liquid chromatography-tandem mass spectrometry employing atmospheric pressure photo ionization (APPI). Results In Group-400, the FF hormone profile confirmed a significant reduction of estradiol in homozygous 677TT carriers (0.52 ± 0.08-fold, exact p = 0.032) and for the first time also revealed significantly reduced estriol concentrations in these individuals (0.54 ± 0.05-fold, p = 0.016), as compared to wildtype controls. In Group-800, no significant differences were found for concentrations of any of the steroid hormones between homozygous 677TT carriers and wildtype controls. Conclusions The current findings support and extend previous reports on reduced concentrations of specific steroid hormones in follicular fluids of homozygous MTHFR 677C>T mutation carriers. The restoration of the FF hormone profile by elevated-dose folic acid supplementation might impact performing ART in infertile women with the MTHFR 677TT-genotype. Further adequately powered studies are necessary to verify our finding and to demonstrate the clinical effect of enhanced folic supplementation on ovarian function.