Polymorphic variants of folate and choline metabolism genes and the risk of endometriosis-associated infertility

The inconsistent pathogenesis of endometriosis and adenomyosis: insights from endometrial metabolome and microbiome

Endometriosis (EM) and adenomyosis (AM) are interrelated gynecological disorders characterized by the aberrant presence of endometrial tissue and are frequently linked with chronic pelvic pain and infertility, yet their pathogenetic mechanisms remain largely unclear. In this cross-sectional study, we analyzed endometrial samples from 244 participants, split into 91 EM patients, 56 AM patients, and 97 healthy controls (HC). We conducted untargeted liquid chromatography-mass spectrometry (LC-MS) and 5R 16S rRNA sequencing to examine endometrial metabolome and microbiome profiles. Additionally, we integrated transcriptomic analysis using nine transcriptomic data sets to investigate the biological basis of these conditions. Metabolomic profiling and 16S rRNA sequencing revealed distinct metabolic and microbial signatures. Specific pathways, including linoleic acid and glycerophospholipid metabolism, show significant alterations in both conditions. Notably, four metabolites, including phosphatidylcholine 40:8 [PC(40:8)], exhibited marked changes in both EM and AM, suggesting shared pathological features. Furthermore, taxonomic analysis identified unique bacterial species associated with each condition, particularly those belonging to the phylum Proteobacteria, which correlated with altered metabolic signatures. Machine learning models demonstrated high predictive accuracy for differentiating between AM, EM, and HC based on metabolic and microbial signatures. Integrative analysis with transcriptomic data highlighted distinct pathways related to immune response and signaling transduction for each condition. Our study provides fresh insights into the pathogenesis of AM and EM through a multi-omic approach, suggesting potential inconsistencies in the underlying pathogenetic mechanisms.

IMPORTANCE

Existing research highlighted a connection between endometriosis (EM) and adenomyosis (AM), underscoring their overlapping symptoms and potential shared pathophysiological mechanisms. Although the role of microbiota in inflammatory conditions has been acknowledged, comprehensive investigations into the endometrial microbiota in cases of EM and AM have been limited. Previous studies identified distinct microbial communities associated with these conditions; however, they were constrained by small sample sizes and a lack of integrated analyses of microbiota and metabolomics. Furthermore, the ongoing debate over whether EM and AM should be classified as separate diseases or related phenotypes emphasizes the necessity for further exploration of their molecular interactions. Our study uncovers distinct microbial and metabolic signatures associated with each condition, revealing both shared and unique pathways that may contribute to their pathogenesis. Furthermore, the integration of transcriptomic data offers valuable insights into the complex interactions underlying these disorders.

The impact of MTHFR and VDR polymorphisms on endometriosis susceptibility: Insights from a systematic review and meta-analysis

The VDR and MTHFR polymorphisms have been linked to many gynecological and obstetrical diseases. However, there is still a pressing need for a systematic review and meta-analysis to synthesize the current evidence on the association between these variants and endometriosis risk. English and Chinese literature databases were systematically retrieved to find relevant research published up to August 1, 2024. The meta-analytic calculations were implemented in the R language 4.4.1 environment. The odds ratios (ORs) with the corresponding 95 % confidence intervals (95 % CIs) were estimated to assess the magnitude of the effect. In total, 26 datasets comprising 9300 subjects were included. The pooled estimate demonstrated a significant association between the MTHFR C677T polymorphism and endometriosis susceptibility in the allele model (OR: 1.41, 95 % CI: 1.07-1.86, P = 0.01), homozygote model (OR: 2.09, 95 % CI: 1.56-2.79, P < 0.01), dominant model (OR: 1.48, 95 % CI: 1.06-2.07, P = 0.02), and recessive model (OR: 1.81, 95 % CI: 1.38-2.37, P < 0.01). However, the meta-analysis for the MTHFR A1298C polymorphism and the VDR FokI, TaqI, ApaI, and BsmI polymorphic variants did not find statistical significance. In conclusion, this meta-analysis suggests that the MTHFR C677T polymorphism might play a role in developing endometriosis disease. Meanwhile, further large-scale validations that consider multiple factors are warranted to confirm this finding.

DNA methylation profiles of ovarian cysts resemble ovarian tissues but not endometrial tissues

INTRODUCTION

Endometriosis is a heritable, complex chronic inflammatory disease, for which much of the causal pathogenic mechanism remain unknown.Despite the high prevalence of ovarian chocolate cyst, its origin is still under debate.

METHODS

Prevailing retrograde menstruation model predicts that ectopic endometrial cells migrate and develop into ovarian chocolate cyst. However, other models were also proposed. Genome-wide association studies (GWASs) have proved successful in identifying common genetic variants of moderate effects for various complex diseases.

RESULTS

A growing body of evidence shows that the remodeling of retrograde endometrial tissues to the ectopic endometriotic lesions involves multiple epigenetic alterations, such as DNA methylation, histone modification, and microRNA expression.Because DNA methylation states exhibit a tissue specific pattern, we profiled the DNA methylation for ovarian cysts and paired eutopic endometrial and ovarian tissues from four patients. Surprisingly, DNA methylation profiles showed the ovarian cysts were closely grouped with normal ovarian but not endometrial tissues.

CONCLUSIONS

These results suggested alterative origin of ovarian cysts or strong epigenetic reprogramming of infiltrating endometrial cells after seeding the ovarian tissue. The data provide contributing to the pathogenesis and pathophysiology of endometriosis.

Homozygous C677T Methylenetetrahydrofolate Reductase (MTHFR) Polymorphism as a Risk Factor for Endometriosis: A Retrospective Case-Control Study

This study was conducted to evaluate the role of methylenetetrahydrofolate reductase (MTHFR) C677T homozygous polymorphism as a risk factor for endometriosis. A retrospective case-control study was conducted from January 2020 to December 2022 on all patients attending the gynecological outpatient clinic of our institution who had performed an MTHFR polymorphisms test. Patients with endometriosis were considered cases, while those without endometriosis were considered controls. The presence of an MTHFR C677T homozygous polymorphism was defined as exposure. Risk factors for endometriosis were considered confounders in a binomial logistic regression, with endometriosis diagnosis as the dependent variable. Among the 409 included patients, 106 (25.9%) cases and 303 (74.1%) controls were identified. A higher rate of MTHFR C677T homozygous polymorphism was found in patients with endometriosis (24.5% vs. 15.8%, p = 0.0453), with an adOR of 1.889 (95% CI 1.076-3.318, p = 0.0269) at the binomial logistic regression. A history of no previous pregnancy was associated with an endometriosis diagnosis (adOR 2.191, 95% CI 1.295-3.708, p = 0.0035). An MTHFR C677T homozygous polymorphism could be considered a risk factor for endometriosis. Epigenetic modifications may be the most important mechanism explaining the observed association through the processes of altered DNA methylation and reduced activity of antioxidant systems.

Emerging hallmarks of endometriosis metabolism: A promising target for the treatment of endometriosis

Endometriosis, characterized by ectopic endometrium growth in the extrauterine environment, is one of the most notable diseases of the female reproductive system. Worldwide, endometriosis affects nearly 10 % of women in their reproductive years and causes a significant decline in quality of life. Despite extensive investigations of endometriosis over the past years, the mechanisms of endometriosis pathogenesis remain unclear. In recent years, metabolic factors have increasingly been considered factors in endometriosis. There is compelling evidence regarding the progress of endometriosis in the context of severe metabolic dysfunction. Hence, the curative strategies and ongoing attempts to conquer endometriosis might start with metabolic pathways. This review focuses on metabolic mechanisms and summarizes current research progress. These findings provide valuable information for the non-intrusive diagnosis of the disease and may contribute to the understanding of the pathogenesis of endometriosis.

Investigation of biomarkers in Endometriosis-associated infertility: Systematic Review

The relationship between endometriosis and infertility is still unknown, but it is possible that genetic polymorphisms influence these two variables. This study aims to identify, in the literature, which polymorphisms are related to infertility in women with endometriosis. A search was performed in databases using the descriptors: polymorphisms genetics and infertility and endometriosis. 386 articles were identified, and after applying the inclusion and exclusion criteria, 33 case-control studies were included. Genes and their respective polymorphisms, which exhibited statistically significant values, were classified into three categories: related to metabolic/cellular processes, steroidogenesis and sex hormone receptors, inflammation and immune response. In summary, the results of these studies suggest that the polymorphisms rs882605 of MUC4 gene, rs16826658 of WNT4 gene, rs10953316 of MUC17 gene, rs10928050 of KAZN gene, rs1799889 of PAI-1 gene, (TA)n repeats of ESR1 gene, (CA)n repeats of ESR2 gene, rs605059 of HSD17B1 gene, rs743572 of CYP17A1 gene, insLQ of LHR gene, p.Ile49Ser of AMH gene, rs12700667 of NPVF/NFE2L3 gene, G1502A of LHβ gene, G + 1730A of ERβ gene, rs7528684 of FCRL3 gene, rs3761549 of FOXP3 gene and rs28362491 of NFKβ1 gene are implicated in the etiology of infertility in women with endometriosis.

Betaine consumption as a new clinical approach to treatment and prophylaxis of folate-related pathologies

The most important pathway in the development of folate-related pathologies is an increase in the level of homocysteine (HC). HC, a cytotoxic and neurotoxic amino acid (when its level is ≥12 μmol/L), is 1 of the most widely studied compounds in cardiology, neurobiology, oncology, and embryology for the last 20 years. Given its toxicity, the processes of endogenous detoxification of HC are of particular interest to medicine. To date, the most studied pathway is that of remethylation (the conversion of HC to methionine), with the participation of B12- and B9-dependent methionine synthase. Less studied is remethylation with the participation of the choline derivatives betaine and betaine-HC-S-methyltransferase (BHMT). Therefore, the aim of this review was to conduct a theoretical analysis of available information regarding the contribution of betaine metabolism, its enzyme, and its genetic polymorphism to folate metabolism disturbances, and the development of folate-related pathologies. This review emphasizes the potential clinical significance of 2 factors that can influence the remethylation reaction of HC: the use of betaine and identifying the BHMT gene variants and their impact on the risk for developing certain folate-related pathologies, and treatment options. Moreover, with a high level of methylation of the BHMT gene and in the presence of its low-function variants (eg, rs3733890), it is necessary to use betaine as an additional methyl donor, especially during folate therapy. More clinical research is needed to identify the effects of the different BHMT gene variants on the individual risk for folate-related pathologies to better assess the clinical significance, the need for genetic testing, and betaine consumption.

Importance of polymorphic variants of phosphatidylethanolamine N-methyltransferase (PEMT) gene in the etiology of intrauterine fetal death in the Polish population

OBJECTIVES

Intrauterine fetal death (IUFD) is a multifactorial disorder and one of the most severe obstetrical complications. Our primary aim was to study the possible associations between polymorphic variants of the PEMT gene and IUFD in the Polish population.

STUDY DESIGN

The case-control study involved 76 mothers with IUFD occurrence and 215 mothers of healthy children. Genetic analysis of the four single nucleotide polymorphisms in the PEMT gene (rs4646406, rs4244593, rs897453 and rs12325817) was performed with the PCR/RFLP method.

RESULTS

Three oef the analyzed PEMT polymorphisms (rs4646406, rs4244593, and rs8974) were significantly associated with IUFD in the Polish population. Among them, PEMT variant rs4244593 was associated with increased risk of IUFD in three genetic inheritance models. Results were statistically significant even after applying Bonferroni correction for multiple comparisons (p < 0.0125). The distribution of all haplotypes except TAGC was not different between cases and controls, however, after applying permutation test, none of the haplotypes showed a relation with IUFD.

CONCLUSIONS

The present findings indicate that PEMT polymorphisms may be associated with the susceptibility to IUFD in the Polish population.

Choline metabolic pathway gene polymorphisms and risk for Down syndrome: An association study in a population with folate-homocysteine metabolic impairment

BACKGROUND/OBJECTIVES

Choline is an essential nutrient involved in one-carbon metabolism, but its role in mechanisms underlying meiotic non-disjunction is poorly known. The relationship between folate-homocysteine metabolic pathway gene polymorphism and Down syndrome (DS) risk has been widely analyzed, but there are limited reports on its correlation with choline metabolism. In the present case-control association study, we investigated the relationship of three single-nucleotide polymorphisms (SNPs) (phosphatidylethanolamine N-methyltransferase (PEMT) rs12325817, choline dehydrogenase (CHDH) rs12676 and homocysteine methyltransferase (BHMT) rs3733890) of choline metabolism with risk for DS.

SUBJECT/METHODS

Genotyping of 228 mothers of a down syndrome child (DSM) and 200 control mothers (CMs) for all SNPs was performed by PCR coupled with restriction fragment length polymorphism method.

RESULTS

A significantly increased risk for BHMT +742AA genotype with an odds ratio of 4.96 (95% confidence interval (CI): 1.66-14.88, P=0.0036) was observed. For PEMT rs12325817 and CHDH rs12676, no significant difference in allelic and genotypic frequencies was observed. In genotypic combination analysis considering PEMT -744GG/CHDH +432GG/BHMT +742GG as the reference combination, PEMT -744GC/CHDH +432GG/BHMT +742GG genotypic combination was significantly higher in DSM compared with that in CMs with an odds ratio of 2.061 (95% CI: 1.10-3.86, P=0.0342). We also observed an epistatic interaction between methylenetetrahydrofolate reductase (MTHFR) rs1801133 and choline metabolic pathway gene variants.

CONCLUSIONS

Our findings indicate impaired choline metabolism showing a greater risk for DS, especially in a population associated with homocysteine-folate impairment. Further studies are required to confirm our findings.

A Three-Way Interaction among Maternal and Fetal Variants Contributing to Congenital Heart Defects

Congenital heart defects (CHDs) develop through a complex interplay between genetic variants, epigenetic modifications, and maternal environmental exposures. Genetic studies of CHDs have commonly tested single genetic variants for association with CHDs. Less attention has been given to complex gene-by-gene and gene-by-environment interactions. In this study, we applied a recently developed likelihood-ratio Mann-Whitney (LRMW) method to detect joint actions among maternal variants, fetal variants, and maternal environmental exposures, allowing for high-order statistical interactions. All subjects are participants from the National Birth Defect Prevention Study, including 623 mother-offspring pairs with CHD-affected pregnancies and 875 mother-offspring pairs with unaffected pregnancies. Each individual has 872 single nucleotide polymorphisms encoding for critical enzymes in the homocysteine, folate, and trans-sulfuration pathways. By using the LRMW method, three variants (fetal rs625879, maternal rs2169650, and maternal rs8177441) were identified with a joint association to CHD risk (nominal P-value = 1.13e-07). These three variants are located within genes BHMT2, GSTP1, and GPX3, respectively. Further examination indicated that maternal SNP rs2169650 may interact with both fetal SNP rs625879 and maternal SNP rs8177441. Our findings suggest that the risk of CHD may be influenced by both the intragenerational interaction within the maternal genome and the intergenerational interaction between maternal and fetal genomes.

Betaine-homocysteine methyltransferase 742G>A polymorphism and risk of down syndrome offspring in a Brazilian population

Down syndrome (DS) is the most common form of mental retardation of genetic etiology. Several polymorphisms in genes involved with the folic acid cycle have been associated to the risk of bearing a DS child; however, the results are controversial. Betaine-homocysteine methyltransferase (BHMT) is a key enzyme of folate pathway, and catalyzes the remethylation of homocysteine into methionine. Recent studies suggest that the polymorphism BHMT 742G>A may be associated with a decreased risk of having a DS child. We herein investigate the association of this polymorphism with the occurrence of DS in a Brazilian population. We have genotyped 94 mothers of DS infants (DSM) and 134 control mothers (CM) for this polymorphism through PCR-RFLP, and found significant differences for both BHMT 742G>A genotype (P=0.04) and allele (P=0.03) frequencies between DSM and CM. The observed genotypic frequencies were GG=0.45; GA=0.45 and AA=0.10 in CM, and GG=0.54; GA=0.38 and AA=0.02 in DSM. Allelic frequencies were G=0.68 and A=0.32 in CM and G=0.78 and A=0.22 in DSM. The presence of the mutant BHMT 742 A allele decreases 40% the risk of bearing a DS child (OR=0.61; 95% CI: 0.40-0.93; P=0.03), and the risk is diminished up to >80% in association with the homozygous genotype (OR=0.17; 95% CI: 0.04-0.80; P=0.01). Our results indicate that women harboring the single nucleotide polymorphism BHMT 742G>A have a decreased risk of a DS pregnancy, and further studies are necessary to confirm this protective effect.

Association of CHKA polymorphism (rs3794186) with α-fetoprotein levels in hepatocellular carcinoma

Choline kinase α (CHKA) has been identified to be associated with cancer development and progression. In this study, we investigated whether exonic single nucleotide polymorphisms (SNPs) of the CHKA gene are associated with hepatocellular carcinoma (HCC). Among all SNPs in the 3'-untranslated region (UTR), 5'-UTR and the coding region of CHA, only two SNPs (rs3794186 and rs11481) in the 3'-UTR had a heterozygosity above 0.1 and a minor allele frequency above 0.1. Therefore, we selected and assessed these two SNPs (rs3794186 and rs11481) in 189 HCC patients and 194 controls. Genetic data were analyzed using the SNPAnalyzer Pro, SNPStats and Haploview programs. No SNPs of the CHKA gene were found to be associated with the risk of HCC development. Upon analysis of the clinical characteristics of HCC, the genotypic frequency of rs3794186 was significantly associated with serum α-fetoprotein (AFP) levels (P=0.022 in the co-dominant 1 model, P=0.0045 in the dominant model and P=0.0052 in the log-additive model). A significant difference in the allelic frequency of rs3794186 was also observed between the high AFP (>200 ng/ml) group and the low AFP (≤200 ng/ml) group [P=0.009, odds ratio (OR) = 0.33, 95% confidence interval (95% CI) = 0.14-0.75]. The T allele frequency of rs3794186 was lower in the high AFP group (6.6%) compared to that in the low AFP group (17.8%). Our results suggest that CHKA SNPs (rs3794186 and rs11481) are not associated with HCC development; however, rs3794186 may correlate with serum AFP levels in HCC.