A second common mutation in the methylenetetrahydrofolate reductase gene: an additional risk factor for neural-tube defects?

The combined effect of MTHFR C677T and A1298C polymorphisms on the risk of digestive system cancer among a hypertensive population

BACKGROUND AND PURPOSE

The enzyme methylenetetrahydrofolate reductase (MTHFR) plays a crucial role in directing folate species towards nucleotide synthesis or DNA methylation. The MTHFR polymorphisms C677T and A1298C have been linked to cancer susceptibility, but the evidence supporting this association has been equivocal. To investigate the individual and joint associations between MTHFR C677T, A1298C, and digestive system cancer in a Chinese hypertensive population, we conducted a population-based case-control study involving 751 digestive system cancer cases and one-to-one matched controls from the China H-type Hypertension Registry Study (CHHRS).

METHODS

We utilized the conditional logistic regression model to evaluate multivariate odds ratios (ORs) and 95% confidence intervals (CIs) of digestive system cancer.

RESULTS

The analysis revealed a significantly lower risk of digestive system cancer in individuals with the CT genotype (adjusted OR: 0.71; 95% CI 0.52, 0.97; P = 0.034) and TT genotype (adjusted OR: 0.57; 95% CI 0.40, 0.82; P = 0.003; P for trend = 0.003) compared to those with the 677CC genotype. Although A1298C did not show a measurable association with digestive system cancer risk, further stratification of 677CT genotype carriers by A1298C homozygotes (AA) and heterozygotes (AC) revealed a distinct trend within these subgroups.

CONCLUSION

These findings indicate a potential protective effect against digestive system cancer associated with the T allele of MTHFR C677T. Moreover, we observed that the presence of different combinations of MTHFR polymorphisms may contribute to varying susceptibilities to digestive system cancer.

Clinical and laboratory findings and etiologies of genetic homocystinemia: a single-center experience

BACKGROUND

Homocysteine (Hcy) is an endogenous nonprotein sulfur-containing amino acid biosynthesized from methionine by the removal of its terminal methyl group. Hyperhomocysteinemia (HHcy) has been linked to many systemic disorders, including stroke, proteinuria, epilepsy, psychosis, diabetes, lung disease, and liver disease. The clinical effects of high serum Hcy level, also known as hyperhomocysteinemia, have been explained by different mechanisms. However, little has been reported on the clinical and laboratory findings and etiologies of genetic HHcy in children. This study aimed to examine the relationships between clinical features, laboratory findings, and genetic defects of HHcy.

METHODS

We retrospectively evaluated 20 consecutive children and adolescents with inherited HHcy at the pediatric neurology division of Baskent University, Adana Hospital (Adana, Turkey) between December 2011 and December 2022.

RESULTS

Our main finding is that the most common cause of genetic HHcy is MTHFR mutation. The other main finding is that the Hcy level was higher in patients with CBS deficiency and intracellular cbl defects than in MTHFR mutations. We also found that clinical presentations of genetic HHcy vary widely, and the most common clinical finding is seizures. Here, we report the first and only case of a cbl defect with nonepileptic myoclonus. We also observed that mild and intermediate HHcy associated with the MTHFR mutation may be related to migraine, vertigo, tension-type headache, and idiopathic intracranial hypertension. Although some of the patients were followed up in tertiary care centers for a long time, they were not diagnosed with HHcy. Therefore, we suggest evaluating Hcy levels in children with unexplained neurological symptoms.

CONCLUSIONS

Our findings suggest that genetic HHcy might be associated with different clinical manifestations and etiologies. Therefore, we suggest evaluating Hcy levels in children with unexplained neurologic symptoms.

Dutch pharmacogenetics working group guideline for the gene-drug interaction of ABCG2, HLA-B and Allopurinol, and MTHFR, folic acid and methotrexate

The Dutch Pharmacogenetics Working Group (DPWG) aims to facilitate PGx implementation by developing evidence-based pharmacogenetics guidelines to optimize pharmacotherapy. This guideline describes the gene-drug interaction of ABCG2 with allopurinol, HLA-B with allopurinol, MTHFR with folic acid, and MTHFR with methotrexate, relevant for the treatment of gout, cancer, and rheumatoid arthritis. A systematic review was performed based on which pharmacotherapeutic recommendations were developed. Allopurinol is less effective in patients with the ABCG2 p.(Gln141Lys) variant. In HLA-B*58:01 carriers, the risk of severe cutaneous adverse events associated with allopurinol is strongly increased. The DPWG recommends using a higher allopurinol dose in patients with the ABCG2 p.(Gln141Lys) variant. For HLA-B*58:01 positive patients the DPWG recommends choosing an alternative (for instance febuxostat). The DPWG indicates that another option would be to precede treatment with allopurinol tolerance induction. Genotyping of ABCG2 in patients starting on allopurinol was judged to be 'potentially beneficial' for drug effectiveness, meaning genotyping can be considered on an individual patient basis. Genotyping for HLA-B*58:01 in patients starting on allopurinol was judged to be 'beneficial' for drug safety, meaning it is advised to consider genotyping the patient before (or directly after) drug therapy has been initiated. For MTHFR-folic acid there is evidence for a gene-drug interaction, but there is insufficient evidence for a clinical effect that makes therapy adjustment useful. Finally, for MTHFR-methotrexate there is insufficient evidence for a gene-drug interaction.

Inpp5e Regulated the Cilium-Related Genes Contributing to the Neural Tube Defects Under 5-Fluorouracil Exposure

Primary cilia are crucial for neurogenesis, and cilium-related genes are involved in the closure of neural tubes. Inositol polyphosphate-5-phosphatase (Inpp5e) was enriched in primary cilia and closely related to the occurrence of neural tube defects (NTDs). However, the role of Inpp5e in the development of NTDs is not well-known. To investigate whether Inpp5e gene is associated with the neural tube closure, we established a mouse model of NTDs by 5-fluorouracil (5-FU) exposure at gestational day 7.5 (GD7.5). The Inpp5e knockdown (Inpp5e-/-) mouse embryonic stem cells (mESCs) were produced by CRISPR/Cas9 system. The expressions of Inpp5e and other cilium-related genes including intraflagellar transport 80 (Ift80), McKusick-Kaufman syndrome (Mkks), and Kirsten rat sarcoma viral oncogene homolog (Kras) were determined, utilizing quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), western blot, PCR array, and immunofluorescence staining. The result showed that the incidence of NTDs was 37.10% (23 NTDs/62 total embryos) and significantly higher than that in the control group (P < 0.001). The neuroepithelial cells of neural tubes were obviously disarranged in NTD embryos. The mRNA and protein levels of Inpp5e, Ift80, Mkks, and Kras were significantly decreased in NTD embryonic brain tissues, compared to the control (P < 0.05). Knockdown of the Inpp5e (Inpp5e-/-) reduced the expressions of Ift80, Mkks, and Kras in mESCs. Furthermore, the levels of α-tubulin were significantly reduced in NTD embryonic neural tissue and Inpp5e-/- mESCs. These results suggested that maternal 5-FU exposure inhibited the expression of Inpp5e, which resulted in the downregulation of cilium-related genes (Ift80, Mkks, and Kras), leading to the impairment of primary cilium development, and ultimately disrupted the neural tube closure.

Identification of common candidate genes and pathways for Spina Bifida and Wilm's Tumor using an integrative bioinformatics analysis

Spina Bifida (SB) and Wilm's Tumor (WT) are conditions, both associated with children. Several studies have shown that WT later develops in SB patients, which led us to elucidate common key genes and linked pathways of both conditions, aimed at their concurrent therapeutic management. For this, integrated bioinformatics analysis was employed. A comprehensive manual curation of genes identified 133 and 139 genes associated with SB and WT, respectively, which were used to construct a single protein-protein interaction (PPI) network. Topological parameters analysis of the network showed its scale-free and hierarchical nature. Centrality-based analysis of the network identified 116 hubs, of which, 6 were called the key genes attributed to being common between SB and WT besides being the hubs. Gene enrichment analysis of the 5 most essential modules, identified important biological processes and pathways possibly linking SB to WT. Additionally, miRNA-key gene-transcription factor (TF) regulatory network elucidated a few important miRNAs and TFs that regulate our key genes. In closing, we put forward TP53, DICER1, NCAM1, PAX3, PTCH1, MTHFR; hsa-mir-107, hsa-mir-137, hsa-mir-122, hsa-let-7d; and YY1, SOX4, MYC, STAT3; key genes, miRNAs and TFs, respectively, as the key regulators. Further, MD simulation studies of wild and Glu429Ala forms of MTHFR proteins showed that there is a slight change in MTHFR protein structure due to Glu429Ala polymorphism. We anticipate that the interplay of these three entities will be an interesting area of research to explore the regulatory mechanism of SB and WT and may serve as candidate target molecules to diagnose, monitor, and treat SB and WT, parallelly.Communicated by Ramaswamy H. Sarma.

The Implication of a Polymorphism in the Methylenetetrahydrofolate Reductase Gene in Homocysteine Metabolism and Related Civilisation Diseases

Methylenetetrahydrofolate reductase (MTHFR) is a key regulatory enzyme in the one-carbon cycle. This enzyme is essential for the metabolism of methionine, folate, and RNA, as well as for the production of proteins, DNA, and RNA. MTHFR catalyses the irreversible conversion of 5,10-methylenetetrahydrofolate to its active form, 5-methyltetrahydrofolate, a co-substrate for homocysteine remethylation to methionine. Numerous variants of the MTHFR gene have been recognised, among which the C677T variant is the most extensively studied. The C677T polymorphism, which results in the conversion of valine to alanine at codon 222, is associated with reduced activity and an increased thermolability of the enzyme. Impaired MTHFR efficiency is associated with increased levels of homocysteine, which can contribute to increased production of reactive oxygen species and the development of oxidative stress. Homocysteine is acknowledged as an independent risk factor for cardiovascular disease, while chronic inflammation serves as the common underlying factor among these issues. Many studies have been conducted to determine whether there is an association between the C677T polymorphism and an increased risk of cardiovascular disease, hypertension, diabetes, and overweight/obesity. There is substantial evidence supporting this association, although several studies have concluded that the polymorphism cannot be reliably used for prediction. This review examines the latest research on MTHFR polymorphisms and their correlation with cardiovascular disease, obesity, and epigenetic regulation.

MTHFR A1298C polymorphism: a predictor of reduced risk of preeclampsia in Punjab, Pakistan

OBJECTIVES

This study aimed to investigate the genetic association between MTHFR (A1298C) SNP and preeclampsia (PE) in Punjab, Pakistan.

METHODS

A sample of 80 pregnant women (40 healthy pregnant women and 40 with PE) was pooled for genotyping MTHFR A1298C polymorphism by using the tetra-primer amplification refractory mutation system (ARMS) PCR. The Genotypic and allelic assessments were performed using various statistical techniques.

RESULTS

The AC genotype and C allele of MTHFR A1298C were found to be associated with decreased risk of PE (odds ratio [OR]: 0.31, risk ratio [RR]: 0.58, p = 0.01), and (odds ratio [OR]: 0.49, risk ratio [RR]: 0.61, p = 0.04), respectively.

CONCLUSION

In conclusion, genetic polymorphism A1298C in MTHFR may pose a protective effect in the studied population.

MTHFR C677T and A1298C polymorphism's effect on risk of colorectal cancer in Lynch syndrome

Lynch syndrome (LS) is characterised by an increased risk of developing colorectal cancer (CRC) and other extracolonic epithelial cancers. It is caused by pathogenic germline variants in DNA mismatch repair (MMR) genes or the EPCAM gene, leading to a less functional DNA MMR system. Individuals diagnosed with LS (LS individuals) have a 10-80% lifetime risk of developing cancer. However, there is considerable variability in the age of cancer onset, which cannot be attributed to the specific MMR gene or variant alone. It is speculated that multiple genetic and environmental factors contribute to this variability, including two single nucleotide polymorphisms (SNPs) in the methylenetetrahydrofolate reductase (MTHFR) gene: C677T (rs1801133) and A1298C (rs1801131). By decreasing MTHFR activity, these SNPs theoretically reduce the silencing of DNA repair genes and increase the availability of nucleotides for DNA synthesis and repair, thereby protecting against early-onset cancer in LS. We investigated the effect of these SNPs on LS disease expression in 2,723 LS individuals from Australia, Poland, Germany, Norway and Spain. The association between age at cancer onset and SNP genotype (risk of cancer) was estimated using Cox regression adjusted for gender, country and affected MMR gene. For A1298C (rs1801131), both the AC and CC genotypes were significantly associated with a reduced risk of developing CRC compared to the AA genotype, but no association was seen for C677T (rs1801133). However, an aggregated effect of protective alleles was seen when combining the alleles from the two SNPs, especially for LS individuals carrying 1 and 2 alleles. For individuals with germline pathogenic variants in MLH1, the CC genotype of A1298C was estimated to reduce the risk of CRC significantly by 39% (HR = 0.61, 95% CI 0.42, 0.89, p = 0.011), while for individuals with pathogenic germline MSH2 variants, the AC genotype (compared to AA) was estimated to reduce the risk of CRC by 26% (HR = 0.66, 95% CI 0.53, 0.83, p = 0.01). In comparison, no association was observed for C677T (rs1801133). In conclusion, our study suggests that combining the MMR gene information with the MTHFR genotype, including the aggregated effect of protective alleles, could be useful in developing an algorithm that estimates the risk of CRC in LS individuals.

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.

Genetic Modulation of HPV Infection and Cervical Lesions: Role of Oxidative Stress-Related Genes

Human papillomavirus (HPV) infection is a necessary but not sufficient factor for the development of invasive cervical cancer (ICC) and high-grade intraepithelial lesion (HSIL). Oxidative stress is known to play a crucial role in HPV infection and carcinogenesis. In this study, we comprehensively investigate the modulation of HPV infection, HSIL and ICC, and ICC through an exploration of oxidative stress-related genes: CβS, MTHFR, NOS3, ACE1, CYBA, HAP, ACP1, GSTT1, GSTM1, and CYP1A1. Notably, the ACE1 gene emerges as a prominent factor with the presence of the I allele offering protection against HPV infection. The association of NOS3 with HPV infection is perceived with the 4a allele showing a protective effect. The presence of the GSTT1 null mutant correlates with increased susceptibility to HPV infection, HSIL and ICC, and ICC. This study also uncovers intriguing epistatic interactions among some of the genes that further accentuate their roles in disease modulation. Indeed, the epistatic interactions between the BB genotype (ACP1) and DD genotype (ECA1) were shown to increase the risk of HPV infection, and the interaction between BB (ACP1) and 0.0 (GSTT1) was associated with HPV infection and cervical lesions. These findings underscore the pivotal role of four oxidative stress-related genes in HPV-associated cervical lesions and cancer development, enriching our clinical understanding of the genetic influences on disease manifestation. The awareness of these genetic variations holds potential clinical implications.

Influence of MTHFR polymorphism, alone or in combination with smoking and alcohol consumption, on cancer susceptibility

5,10-methylenetetrahydrofolate reductase (MTHFR) mutations play a significant role in various types of cancers, serving as crucial regulators of folate levels in this process. Several studies have examined the effects of smoking and drinking on MTHFR-related cancers, yielding inconsistent results. Therefore, the objective of this study was to evaluate the magnitude of the effects of gene-smoking or gene-drinking interactions on cancer development. We conducted a comprehensive literature search in PubMed, Web of Science, CNKI, and Wan Fang databases up until May 10th, 2022, to identify relevant articles that met our inclusion criteria. The extracted data from these studies were used to calculate the overall odds ratio (OR) and corresponding 95% confidence interval (95% CI) using either a fixed-effect or random-effect model in Stata version 11.2. Stratified analyses were performed based on ethnicity, control group origin, and cancer classification to assess the risk of cancers associated with gene-smoking or gene-drinking interactions. Sensitivity analyses were conducted to investigate potential sources of heterogeneity, and publication bias was assessed using the Begg's test and Egger's test. Additionally, regression analysis was employed to explore the influence of relevant variables on heterogeneity. To evaluate the statistical correlations, analytical methods such as the false-positive report probability and the Bayesian false discovery probability were applied to assess the reliability of the findings. In our meta-analysis, a total of 47 articles were included, comprising 13,701 cases and 21,995 controls for the C677T polymorphism and 5,149 cases and 8,450 controls for the A1298C polymorphism. The results indicated a significant association between C677T polymorphism and cancer risks when combined with smoking (CT + TT vs CC, OR [95% CI] = 1.225 [1.009-1.487], p = 0.041). Stratified analysis further revealed a significant increase in liver cancer risk for individuals with the C677T when combined with smoking (liver cancer: CT + TT vs CC, OR [95% CI] = 1.564 [1.014-2.413], p = 0.043), particularly among Asian smokers (CT + TT vs CC, OR [95% CI] = 1.292 [1.007-1.658], p = 0.044). Regarding the A1298C polymorphism, an elevated risk of cancer was observed in mixed populations alone (CC + AC vs AA, OR [95% CI] = 1.609 [1.087-2.381], p = 0.018), as well as when combined with smoking (CC + AC vs AA, OR [95% CI] = 1.531 [1.127-2.080], p = 0.006). In non-drinkers, C677T polymorphism was found to be associated with esophageal cancer risk (C677T: CT + TT vs CC, OR [95% CI] = 1.544 [1.011-2.359], p = 0.044) and colon cancer risk (CC + AC vs AA, OR [95% CI] = 1.877 [1.166-3.054], p = 0.010), but there was no clear link between this polymorphism and cancer risk among drinkers. The association between the C677T polymorphism and cancer risk among smokers was found to be significant, suggesting that the combination of tobacco and the C677T polymorphism may enhance the carcinogenic process, particularly in liver cancer. However, no similar relationship was observed for the A1298C polymorphism. Interestingly, significantly increased cancer risk was observed in individuals with C677T genetic variants who were nondrinkers, but not among drinkers. These findings highlight the potential role of the C677T polymorphism in modifying cancer risk in specific contexts, such as smoking and alcohol consumption.

Consistent Correlation between MTHFR and Vascular Thrombosis in Neonates-Case Series and Clinical Considerations

BACKGROUND

MTHFR polymorphism has been inconsistently linked to thrombotic events-some studies have shown its contribution to venous thrombosis, arterial thrombosis, and ischemic stroke, whereas others have found no statistically significant correlation between them.

METHODS

A descriptive case series study was performed in the Neonatal Intensive Care Unit of "Marie Sklodowska Curie" Emergency Clinical Hospital for Children in Bucharest, Romania.

RESULTS

All patients had positive results for MTHFR variants; 14 patients were positive for compound heterozygosity, 13 patients for MTHFR C677T (seven of which were homozygous), and 13 patients for MTHFR A1298C (three of which were homozygous). Eighteen patients received anticoagulants (heparin, enoxaparin, or bivalirudin), and thrombolytics (alteplase) were administered in six cases. In one case, a thrombectomy was performed; in another, vascular plasty was undertaken. Only in six cases was complete revascularization possible. Incomplete revascularization occurred for one patient with a negative outcome.

CONCLUSION

The particularity of this case series is that every patient in our unit who developed thrombi had a positive genetic result for MTHFR mutations. MTHFR mutations should be regarded as a thrombotic risk factor for critically ill patients, and screening for MTHFR mutations should be performed in every admitted patient to intensive care units, thus achieving the prevention of thrombi.

Inherited Thrombophilia Associated With Ischemic Pediatric Stroke in Parent-Child Pairs

BACKGROUND

We aimed to examine inherited thrombophilia frequencies by extending genetic profile to previously rarely or not investigated polymorphisms in children with ischemic pediatric stroke (IPS) and their parents.

METHODS

The study included 33 children: 23 with perinatal arterial ischemic stroke (PAIS), eight with childhood arterial ischemic stroke (CAIS), and two with sinovenous thrombosis and their parents (33 mother-child, 12 father-child, and 12 mother-father-child pairs). Genotyping of FV-Leiden, FV-H1299R, FII-G20210A, β-fibrinogen-455G>A, FXIII-A-Val34Leu, PAI-1(4G/5G), HPA-1, MTHFR-C677T, MTHFR-A1298C, ACE(I/D), and APOE(ε2-4) was performed using CVD Strip assay (ViennaLab, Austria).

RESULTS

At least one and up to seven simultaneously present polymorphisms were observed in all children with IPS, mothers, and fathers. More than five simultaneously present polymorphisms were identified threefold more frequently in children with IPS (10 of 33; 30%) compared with the child control group (17 of 150; 11%), yielding a statistically significant difference between the two groups (odds ratio [OR] = 3.40; 95% confidence interval [CI] = 1.39 to 8.35; P = 0.012). Stronger association was revealed for PAIS (OR = 4.17; 95% CI = 1.55 to 11.29; P = 0.008) and CAIS subgroups (OR = 7.82; 95% CI = 1.79 to 34.20; P = 0.012). Complete match of polymorphisms was not identified in any parent-child pair. A partial match (one to four mutual polymorphisms) was found in 11 of 12 parent-child pairs where until three mutual polymorphisms was present in 11 of 12 (91.7%) father-child compared with 21 of 33 (63.6%) mother-child pairs.

CONCLUSIONS

According to obtained results the simultaneous presence of more than five polymorphisms is associated with a higher risk for IPS occurrence, suggesting the risk enhancement for PAIS in the presence of pregnancy complications or for CAIS in conjunction with maternal comorbidity and positive family history. The presence of up to three mutual polymorphisms more frequently in father-child than mother-child pairs suggests significant paternal contribution of inherited thrombophilia to increased risk of IPS.

Childhood Neurological Disorders With Hyperhomocystinemia: A Case-Based Review

Hyperhomocysteinemia is a rare neurometabolic syndrome with diverse manifestations in the pediatric age group, thereby posing a diagnostic challenge. Biochemical testing is imperative to guide plan of evaluation, which may include appropriate genetic testing, in inherited disorders. Through this case-based approach, we demonstrate the heterogeneity of clinical presentation, biochemical and genetic evaluation, and treatment strategies that may reverse this condition among children.

Homocysteine serum levels correlate with the number of failed IVF cycles even when within normal range

INTRODUCTION

Repeated implantation failure is a common challenge in daily practice. Homocysteine and vitamin B12 have been associated with reproductive processes among patients undergoing in vitro fertilization; however, their involvement in repeated implantation failure has not been assessed. We explored possible associations of serum homocysteine and vitamin B12 with repeated implantation failure.

MATERIAL AND METHODS

A retrospective analysis of 127 women who underwent ≥ 3 unsuccessful embryo transfers during 2005-2016, at the Fertility and In Vitro Fertilization Unit at Carmel Medical Center. After at least 3 IVF failures serum levels of homocysteine and vitamin B12 were measured.

RESULTS

The mean patient age was 33.5 ± 5.2 years. The mean number of embryo transfers was 4.6 ± 1.5. The mean total cumulative number of embryos transferred was 10.4 ± 5.2. Mean serum levels of homocysteine were 8.6 ± 3.7 µM/L, and of vitamin B12 were 302.5 ± 155.3 pg/ml. Homocysteine levels were within the normal range (< 14 µM/L) in 95.8% of the patients. Yet, the levels of homocysteine correlated with both the number of failed embryo transfers (r = 0.34, p = 0.004) and the total cumulative number of transferred embryos (r = 0.36, p = 0.002).

CONCLUSIONS

Our findings suggest an association between serum homocysteine levels and the occurrence of repeated implantation failure, even when homocystein levels were within the normal range. It should be studied whether nutritional supplementation to modulate serum homocysteine levels may improve treatment outcome.

Folate-dependent hypermobility syndrome: A proposed mechanism and diagnosis

Hypermobility involves excessive flexibility and systemic manifestations of connective tissue fragility. We propose a folate-dependent hypermobility syndrome model based on clinical observations, and through a review of existing literature, we raise the possibility that hypermobility presentation may be dependent on folate status. In our model, decreased methylenetetrahydrofolate reductase (MTHFR) activity disrupts the regulation of the ECM-specific proteinase matrix metalloproteinase 2 (MMP-2), leading to high levels of MMP-2 and elevated MMP-2-mediated cleavage of the proteoglycan decorin. Cleavage of decorin leads ultimately to extracellular matrix (ECM) disorganization and increased fibrosis. This review aims to describe relationships between folate metabolism and key proteins in the ECM that can further explain the signs and symptoms associated with hypermobility, along with possible treatment with 5-methyltetrahydrofolate supplementation.

Nicotinamide riboside supplementation is not associated with altered methylation homeostasis in Parkinson's disease

Replenishing nicotinamide adenine dinucleotide (NAD) via supplementation of nicotinamide riboside (NR) has been shown to confer neuroprotective effects in models of aging and neurodegenerative diseases, including Parkinson's disease (PD). Although generally considered safe, concerns have been raised that NR supplementation could impact methylation dependent reactions, including DNA methylation, because of increased production and methylation dependent breakdown of nicotinamide (NAM). We investigated the effect of NR supplementation on DNA methylation in a double blinded, placebo-controlled trial of 29 human subjects with PD, in blood cells and muscle tissue. Our results show that NR had no impact on DNA methylation homeostasis, including individuals with common pathogenic mutations in the MTHFR gene known to affect one-carbon metabolism. Pathway and methylation variance analyses indicate that there might be minor regulatory responses to NR. We conclude that short-term therapy with high-dose NR for up to 30 days has no deleterious impact on methylation homeostasis.

Impact of methylene-tetrahydrofolate reductase gene C677T and A1298C polymorphisms as a risk factor for hepatitis B virus infection

Chronic hepatitis B infection caused by Hepatitis B virus (HBV), influences over two billion people worldwide despite having an effective vaccine. With a total prevalence of 4.57%, there are 3.3 million estimated HBV carriers in Türkiye. Methylene-tetrahydrofolate reductase (MTHFR) arrange folate metabolism through nucleic acid synthesis and DNA methylation. C677T (rs1801133, p.Ala222Val) and A1298C (rs1801131, p.Glu429Ala) polymorphisms of MTHFR gene have effect of reducing the activity of enzyme. We purposed to investigate the correlation between C677T and A1298C polymorphisms of MTHFR gene with HBV infection in a Turkish population. One hundred eighteen HBV-infected participants and ninety healthy controls were incorporated in this research. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was applied to discover the genotypes of MTHFR polymorphisms. We demonstrated that T allele and CT + TT genotype frequencies of C677T polymorphism were significantly increased in HBV-infected participants than healthy controls [p = 0.015, OR (95% Cl) = 1.7 (1.11-2.79) and p = 0.020, OR (95% Cl) = 1.9 (1.10-3.42), respectively). No significant associations were noted concerning the A1298C polymorphism (p > 0.05). CC-AA composite genotype was observed to be significantly elevated in healthy controls than HBV-infected participants (32.2% vs. 13.6%, p = 0.001). In addition, the frequency of T-C haplotype was found to be considerably higher in the patient group than control group (15.8% vs 11.8%, p = 0.018). In conclusion, we found that T allele of C677T polymorphism poses a risk factor for HBV infection. We also discovered a protective impact of the CC-AA composite genotype against HBV infection and a risk effect of the T-A haplotype for HBV-infection.

Effects of Methylenetetrahydrofolate Reductase (MTHFR) Polymorphisms on Retinal Tissue Perfusion in Mild Diabetic Retinopathy Patients Receiving the Medical Food, Ocufolin®

Purpose

We evaluate the effects of methylenetetrahydrofolate reductase (MTHFR) polymorphisms on retinal tissue perfusion in patients with mild diabetic retinopathy (DR + PM) taking the medical food, Ocufolin^®, for 6 months.

Methods

Prospective, case-controlled study. Eight early diabetic retinopathy patients with common reduced function MTHFR polymorphisms (DR+PM) and 15 normal controls (NC) were recruited. MTHFR polymorphisms were subtyped as normal, C677T, or A1298C. Best corrected visual acuity (BCVA) was evaluated. Retinal blood flow velocity (BFV) was measured using Retinal Function Imager. Retinal tissue perfusion (RTP, blood flow rate per inner retinal volume) was calculated within a 2.5 mm diameter circle centered on the fovea. The medical food is intended to address ocular ischemia with high doses of vitamin B-complexes and antioxidants, including L-methylfolate, methylcobalamin, zinc, copper, lutein, vitamins C, D, E, and n-acetylcysteine. The subjects were provided with a medical food for a period of 6 months.

Results

BCVA and vascular indices of DR + PM patients at baseline were initially below those of NC and improved after medical food. Compared to baseline, DR + PM patients after the medical food had significantly improved BCVA during the follow-up period (P < 0.05). In comparison, overall RTP and arteriolar BFV were significantly increased at 6 months (P < 0.05). The changes varied with MTHFR subtypes. In patients with the C677T and the C677T/A1298C compound mutations, RTP was increased at 6 months as compared to that at baseline and 4 months (P < 0.05). In patients with only the A1298C mutation, all microcirculation metrics were increased from baseline at 4 and 6 months, but with less improvement at 6 months than at 4 months (P < 0.05).

Conclusion

Medical food was effective in improving both visual acuity and retinal tissue perfusion in DR + PM patients. The degree of improvement of retinal microcirculation varied among MTHFR subtypes.

The methylenetetrahydrofolate reductase C677T and A1298C genetic polymorphisms and plasma homocysteine in Alzheimer's disease in an Algerian population

BACKGROUND

The etiology of Alzheimer's disease (AD) is multifactorial. The most important challenge of research is the identification of potential biomarkers associated with AD pathogenesis that may significantly contribute to early diagnosis of the disease. We aim to explore an eventual association of the C677T and A1298C genetic polymorphisms in the MTHFR gene with AD risk in an Algerian population.

METHODS

This case-control study involved comparing a group of 106 patients that had developed AD to another group of 104 non-demented individuals. The MTHFR genotypes were determined using PCR-RFLP method. Additionally, the homocysteine level was evaluated.

RESULTS

Genotypes analysis did not show an association for both MTHFR677CT and 677TT variants with AD risk (OR = 1.12; p = 0.66; OR = 1.76; p = 0.09) respectively. As expected, the 677CC wild type genotype showed a protective role against AD (OR = 0.52; p = 0.03). For 1298AC MTHFR variant, the distribution of different genotypes did not show a statistical significant difference between the two cohorts. However the silmutaneous carrier, CT/AC presented association with AD (OR = 5.96; p = 0.05). On the other hand, carrier-state of MTHFR T allele showed a relationship with AD (OR = 1.98; p = 0.02). Additionally, hyperhomocysteinemia seems to be a risk factor for AD (OR = 1.08; p = 0.02).

CONCLUSION

Our exploration reveals that the silmutaneous carrier, CT/AC, carrier-state of MTHFR T allele, and hyperhomocysteinemia seem to be risk factors for AD.

MTHFR polymorphism's influence on the clinical features and therapeutic effects in patients with migraine: An observational study

Objective

Our study aimed to evaluate the influence of methylenetetrahydrofolate reductase (MTHFR) polymorphism on the clinical features and therapeutic effects in patients with migraine.

Methods

The data of 135 patients with migraine were collected from January 2021 to December 2021. The MTHFR C677T polymorphism was analyzed. The pain intensity was evaluated using a numerical rating scale (NRS) during treatment. The levels of folic acid, homocysteine (Hcy), vitamin B12, interleukin-2 (IL-2), IL-4, and ferritin, and changes of NRS were compared between folic acid and conventional treatment groups stratified by different genotypes of MTHFR in migraine patients.

Results

The levels of Hcy and ferritin in male patients were higher than that in female patients (P < 0.05); Compared with CC and CT genotype groups, the TT genotype group showed significantly higher Hcy levels (P < 0.05) and lower folic acid levels (P < 0.05); In both folic acid and conventional treatment groups, a significant decrease in NRS score was observed in different genotypes post-treatment (P < 0.05). Patients with TT genotype in the folic acid treatment group showed better therapeutic efficacy than conventional treatment group (P < 0.05). There is no significant difference in the therapeutic efficacy in other genotypes between the two groups (P > 0.05).

Conclusion

The MTHFR C677T genotyping may provide a new method to guide and optimize individualized medication for migraine patients.

Association of selected genetic variants in CBS and MTHFR genes in a cohort of children with homocystinuria in Sri Lanka

BACKGROUND

Homocystinuria is an inherited, inborn error of homocysteine metabolism, which leads to the abnormal accumulation of homocysteine and its metabolites in blood and urine, resulting in various complications. Variants in the cystathionine β-synthase (CBS) and methylenetetrahydrofolate reductase (MTHFR) genes interrupt the formation of the corresponding enzymes and prevent homocysteine from being metabolised; hence, the homocysteine levels in plasma increase than the optimum levels.

MATERIALS AND METHODS

In the current study, eight clinically confirmed children with homocystinuria were detected to study the chosen variants in the CBS gene (c.833 T>C and c.19del) and in the MTHFR gene (c.665 C>T, c.1286 A>C) using SNaPshot mini-sequencing and direct sequencing.

RESULTS

After screening eight patients, none had the c.833T>C, but four patients were in the homozygous state for the c.19del variant in the CBS gene. Furthermore, seven were heterozygous for c.1286A>C, while one patient was heterozygous for c.665C>T in the MTHFR gene.

CONCLUSION

According to the results, c.19del is common in the studied cohort of Sri Lankan children, while c.833T>C is absent, whereas c.1286A>C was more frequent than c.665C>T. To our knowledge, the current study was the first report to discuss the genetic impact of homocystinuria in Sri Lanka; further comprehensive studies are necessary with a larger sample size to establish the association of these variants with the disease in Sri Lanka, which can be beneficial in enhanced patient care and for prospective studies.

Association between maternal MTHFR C677T/A1298C combination polymorphisms and IVF/ICSI outcomes: a retrospective cohort study

STUDY QUESTION

What are the roles of maternal 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T/A1298C combination polymorphisms on the embryological and clinical outcomes of IVF/ICSI?

SUMMARY ANSWER

Our study reveals for the first time that the oocyte maturation potential gradually decreases with a reduction of maternal MTHFR activity determined by combined C677T/A1298C polymorphisms, while embryo quality was worse in women with intermediate MTHFR activity.

WHAT IS KNOWN ALREADY

Although many previous studies have explored the association between MTHFR polymorphisms and IVF/ICSI outcomes, the results remain contradictory due to inadequate samples, no adjustment for potential confounders and/or the study of C677T and A1298C separately. Few studies have systematically investigated the exact role of MTHFR activity determined by combined C677T/A1298C polymorphisms on the embryological and clinical outcomes of IVF/ICSI.

STUDY DESIGN SIZE DURATION

This is a retrospective cohort study investigating 1160 women who were referred for MTHFR genotyping and IVF/ICSI treatment at Peking University Third Hospital from May 2017 to May 2020.

PARTICIPANTS/MATERIALS SETTING METHODS

Women who were referred for MTHFR genotyping and their first IVF/ICSI treatment at our hospital were included and those undergoing preimplantation genetic testing cycles were excluded. The included women were divided into different cohorts according to their C677T, A1298C and combined C677T/A1298C genotypes. The embryological outcomes, including oocytes retrieved, metaphase II oocytes, oocyte maturation rate, normal fertilization rate and transplantable embryo rate, were evaluated by generalized linear regression models. The clinical outcomes, including biochemical pregnancy rate, clinical pregnancy rate and live birth rate, were evaluated by log-binomial regression models. All outcomes were adjusted for potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

Women with the combined 677TT/1298AA genotype (hereafter abbreviated as TT/AA, as with other combined genotypes), whose enzyme activity was the lowest, had a lower oocyte maturation rate compared with those with the wild-type genotype (P = 0.007). Moreover, the oocyte maturation rate decreased linearly with the decline in MTHFR enzyme activity determined by combined C677T/A1298C genotypes (P-trend = 0.001). The combined CC/AC, CC/CC&CT/AA and CT/AC genotypes with intermediate enzyme activity were associated with a lower transplantable embryo rate (P = 0.013, 0.030 and 0.039, respectively). The differences in clinical outcomes between women with wild-type genotype and combined C677T/A1298C variant genotypes were not significant.

LIMITATIONS REASONS FOR CAUTION

Our study population had comparable embryological outcomes but worse clinical outcomes than other women undergoing IVF/ICSI treatment at our hospital. Therefore, the results related to the clinical outcomes should be generalized with caution. In addition, we did not detect the folate concentration of each patient during pregnancy. However, this might not have much influence on our results because almost all of our study participants took sufficient folic acid around pregnancy.

WIDER IMPLICATIONS OF THE FINDINGS

We provide a holistic view of the effect of MTHFR C677T and A1298C polymorphisms on the IVF/ICSI outcomes, which can contribute to providing reasonable folic acid supplementation suggestions for women with different MTHFR genotypes, especially for those with a low oocyte maturation rate and/or low embryo quality.

STUDY FUNDING/COMPETING INTERESTS

This work was funded by the National Natural Science Foundation of China (31871447, and 82101677), the National Key Research and Development Program (2019YFA0801400) and the Natural Science Foundation of Beijing Municipality (7202226). The authors declare that they have no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

The Role of Single-Nucleotide Polymorphisms in Cholangiocarcinoma: A Systematic Review

Single-nucleotide polymorphisms (SNPs) play an essential role in various malignancies, but their role in cholangiocarcinoma (CCA) remains to be elucidated. Therefore, the purpose of this systematic review was to evaluate the association between SNPs and CCA, focusing on tumorigenesis and prognosis. A systematic literature search was carried out using PubMed, Embase, Web of Science and the Cochrane database for the association between SNPs and CCA, including literature published between January 2000 and April 2022. This systematic review compiles 43 SNPs in 32 genes associated with CCA risk, metastatic progression and overall prognosis based on 34 studies. Susceptibility to CCA was associated with SNPs in genes related to inflammation (PTGS2/COX2, IL6, IFNG/IFN-γ, TNF/TNF-α), DNA repair (ERCC1, MTHFR, MUTYH, XRCC1, OGG1), detoxification (NAT1, NAT2 and ABCC2), enzymes (SERPINA1, GSTO1, APOBEC3A, APOBEC3B), RNA (HOTAIR) and membrane-based proteins (EGFR, GAB1, KLRK1/NKG2D). Overall oncological prognosis was also related to SNPs in eight genes (GNB3, NFE2L2/NRF2, GALNT14, EGFR, XRCC1, EZH2, GNAS, CXCR1). Our findings indicate that multiple SNPs play different roles at various stages of CCA and might serve as biomarkers guiding treatment and allowing oncological risk assessment. Considering the differences in SNP detection methods, patient ethnicity and corresponding environmental factors, more large-scale multicentric investigations are needed to fully determine the potential of SNP analysis for CCA susceptibility prediction and prognostication.

The Association of Methylenetetrahydrofolate Reductase (MTHFR) A1298C Gene Polymorphism with Susceptibility to Diabetic Nephropathy: A Meta-Analysis

This meta-analysis was conducted to investigate the association between MTHFR A1298C polymorphism and susceptibility to diabetic nephropathy. PubMed, Embase, Web of Science, Cochrane Library, China national knowledge infrastructure (CNKI) and China Wanfang database were searched for studies on the association between MTHFR A1298C single nucleotide polymorphism and susceptibility to diabetic nephropathy until May 2022. Data were analyzed by Stata 15.0 software. Odds ratio (OR) was used as the effect size. A total of 7 articles were identified, including 1287 cases in the diabetic nephropathy group and 1431 cases in the control group. The pooled OR of allele C at MTHFR A1298C was 1.28 (95% CI: 1.02-1.59, p=0.03) compared with allele A. The pooled OR values of dominant, and heterozygous genetic models were 1.45 (95% CI: 1.13-1.86), and 1.42 (95% CI: 1.19-1.70), respectively, and the differences were all statistically significant. There was no statistical significance in the recessive (OR=1.06, 95% CI: 0.62-1.82), and homozygous gene inheritance models (OR=1.29, 95% CI: 0.72-2.31). In conclusion, MTHFR A1298C polymorphism is associated with susceptibility to diabetic nephropathy. Allele C, genotype CC+AC, and AC at MTHFR A1298C locus can increase the risk of diabetic nephropathy.

Different effects of maternal homocysteine concentration, MTHFR and MTRR genetic polymorphisms on the occurrence of fetal aneuploidy

RESEARCH QUESTION

Do maternal homocysteine (Hcy) concentrations, MTHFR and MTRR genes have effects on the occurrence of fetal aneuploidy?

DESIGN

A total of 619 aneuploidy mothers and 192 control mothers were recruited in this study. Differences in distributions of maternal MTHFR 677C>T, MTHFR 1298A>C and MTRR 66A>G genetic polymorphisms and maternal Hcy concentrations between aneuploidy mothers and control mothers were analysed.

RESULTS

The maternal MTHFR 677C>T polymorphism was found to be a risk factor for the occurrence of many fetal non-mosaic aneuploidies studied here, including trisomies 13, 15, 16, 18, 21, 22, TRA and TS. The maternal MTHFR 1298A>C polymorphism was found to be a risk factor specifically associated with the occurrence of fetal trisomy 15 and fetal TS. The maternal MTRR 66A>G polymorphism was found to be a risk factor only specifically associated with the occurrence of fetal trisomy 21. The Hcy concentrations of mothers of trisomies 22, 21, 18, 16, 15 and TS fetuses were significantly higher than the Hcy concentrations of control mothers.

CONCLUSIONS

Overall, data suggested an association between these maternal polymorphisms and the susceptibility of fetal non-mosaic trisomy and Turner syndrome. However, these three maternal polymorphisms had different associations with the susceptibility of different fetal aneuploidies, and the elevated maternal Hcy concentration appeared to be a likely risk factor for fetal Turner syndrome and fetal trisomies.

Triglyceride Level- and MTHFR- Specific Mediation Effect of Handgrip Strength on the Association of Dietary Protein Intake and Cognitive Function in the Chinese Elderly

BACKGROUND

Recent findings suggest that both dietary protein intake and hand grip strength (HGS) were associated with cognitive function, however, few studies have been devoted specifically to the mediation effect of HGS on the association of dietary protein with cognitive function.

OBJECTIVES

To confirm the hypothesis that HGS mediated the association of dietary protein intake with cognitive function in the elderly, which was modified by triglyceride level and methylenetetrahydrofolate reductase (MTHFR) gene status.

METHODS

This cross-sectional study included 3,268 participants. Dietary protein intake, HGS, and cognitive function were collected by food frequency questionnaires (FFQ), grip measurements and mini mental state examination (MMSE), respectively. In this mediation analysis, dietary protein intake was entered as independent variable, HGS was entered as mediator, and cognitive function was entered as dependent variable.

RESULTS

HGS significantly mediated the associations of dietary protein (β = 0.0013, 95% CI: 0.0007, 0.0022), animal protein (β = 0.0024, 95% CI: 0.0012, 0.0037), and plant protein intake (β = 0.0011, 95% CI: 0.0001, 0.0023) with cognitive function in total participants, with the mediated proportion of 16.19%, 12.45% and 20.57%, respectively. Furthermore, significant mediation effects of HGS on the associations of dietary protein, animal protein, and plant protein intake with MMSE score were found in the elderly without hypertriglyceridemia or in MTHFR C677T CC/CT carriers.

CONCLUSION

This study suggested that HGS mediated the association of dietary protein intake with cognitive function, and this mediation effect was modified by triglyceride level and MTHFR C677T gene status.

T677T Methylenetetrahydrofolate Reductase Single Nucleotide Polymorphisms Increased Prevalence in a Subgroup of Infertile Patients with Endometriosis

<b><i>Background:</i></b> Approximately 10% (190 million) of women worldwide are affected by endometriosis, ectopic deposits of endometrial tissue that create a major source of pain that affects lifestyle and reproductive function. The pathogenesis of endometriosis is an estrogen-dependent inflammatory process, influenced/catalyzed by oxidative stress and consequently defective methylation, with biochemical features centered around the folate and one-carbon cycles. We aimed to determine whether a link could be found between the two major methylenetetrahydrofolate reductase single nucleotide polymorphisms (MTHFR SNPs), c.677C&gt;T and c.1298A&gt;C, involved in methylation process/epigenetic marking failures, and endometriosis. <b><i>Material and Methods:</i></b> We studied a population of 158 patients in a group of &gt;1500 referred for treatment of infertility. All the patients had experienced &gt;2 failed assisted reproductive technology cycles and/or &gt;2 miscarriages, a classical cohort for investigation in our group. Patients with endometriosis had at least stage 2+ disease confirmed by laparoscopy. <b><i>Results:</i></b> The prevalence of the homozygous c.677C&gt;T isoform is doubled in the endometriosis group, 21.5% versus 10.2% in the non-endometriosis group (<i>p</i> &gt; 0.01). Symmetrically, the percentage of patients in the endometriosis group with the wild type MTHFR significantly decreased by one-half (8.2%-17.2%) in the non-endometriosis group (<i>p</i> &lt; 0.001). <b><i>Conclusion:</i></b> Determination of MTHFR c.677C&gt;T should not be overlooked in patients with harmful endometriosis affecting their fertility. As folates metabolism is impaired in these MTHFR SNPs carrier patients, co-treatment with 5-methyl folate may constitute a successful (co)-treatment modality.

Methodological and Biological Factors Influencing Global DNA Methylation Results Measured by LINE-1 Pyrosequencing Assay in Colorectal Tissue and Liquid Biopsy Samples

Long interspersed nuclear element 1 (LINE-1) bisulfite pyrosequencing is a widely used technique for genome-wide methylation analyses. We aimed to investigate the effects of experimental and biological factors on its results to improve the comparability. LINE-1 bisulfite pyrosequencing was performed on colorectal tissue (n = 222), buffy coat (n = 39), and plasma samples (n = 9) of healthy individuals and patients with colorectal tumors. Significantly altered methylation was observed between investigated LINE-1 CpG positions of non-tumorous tissues (p ≤ 0.01). Formalin-fixed, paraffin-embedded biopsies (73.0 ± 5.3%) resulted in lower methylation than fresh frozen samples (76.1 ± 2.8%) (p ≤ 0.01). DNA specimens after long-term storage showed higher methylation levels (+3.2%, p ≤ 0.01). In blood collection tubes with preservatives, cfDNA and buffy coat methylation significantly changed compared to K3EDTA tubes (p ≤ 0.05). Lower methylation was detected in older (>40 years, 76.8 ± 1.7%) vs. younger (78.1 ± 1.0%) female patients (p ≤ 0.05), and also in adenomatous tissues with MTHFR 677CT, or 1298AC mutations vs. wild-type (p ≤ 0.05) comparisons. Based on our findings, it is highly recommended to consider the application of standard DNA samples in the case of a possible clinical screening approach, as well as in experimental research studies.

A retrospective examination of adjunctive L-methylfolate in children and adolescents with unipolar depression

BACKGROUND

Adjunctive l-methylfolate is commonly prescribed for children and adolescents with treatment-resistant mood disorders; however, the relationship between l-methylfolate augmentation across methylenetetrahydrofolate reductase (MTHFR) genotypes in youths with depressive symptoms is unclear.

METHODS

We retrospectively examined the electronic health records of patients (N = 412) with depressive symptoms associated with unipolar depressive disorders and their MTHFR C677T genotypes from 2013 to 2019. Patients were ≤18 years of age at the time of MTHFR pharmacogenetic testing. Treatment response was assessed with Clinical Global Impression-Improvement (CGI-I) score reported in the medical record.

RESULTS

Patients with an MTHFR C677T C/T or T/T genotype were more likely to be prescribed l-methylfolate when the clinician knew their MTHFR genotype (p < 0.0001, OR: 15.1, 95 % CI: [5.1, 44.2]), but not when the clinician did not know their genotype (p = 0.4, OR: 2.1, 95 % CI: [0.4, 11.4]). Change in baseline and endpoint CGI-I scores between patients with an MTHFR C677T variant who were prescribed and not prescribed l-methylfolate did not significantly differ (p = 0.39). Response rate was not associated with l-methylfolate prescription (p = 0.17) or l-methylfolate dose (p = 0.69).

LIMITATIONS

This was a retrospective study, which yielded a heterogeneous patient population and limited data availability (e.g., adherence). Patients are severely ill and may have a refractory illness that limits response to adjunctive l-methylfolate.

CONCLUSION

Clinicians prescribe l-methylfolate to children and adolescents with depressive symptoms associated with unipolar depressive disorders who have an MTHFR C677T variant, although augmentation may not be associated with treatment response, regardless of MTHFR genotype or dose.

Association between variants of MTHFR genes and psychiatric disorders: A meta-analysis

Background

Psychiatric disorders have seriously affected human life, one of the risk genes related to psychosis is the methylenetetrahydrofolatereductase (MTHFR) gene. This gene has a potential role in psychiatric disorders. Therefore, a meta-analysis is conducted to investigate the correlations between two prevalent MTHFR single nucleotide polymorphisms (SNPs), MTHFR C677T, A1298C, severe psychological disorders (schizophrenia, major depression, bipolar disorder).

Methods

A total of 81 published studies were screened and selected by a search of electronic databases up to April 2022. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association between MTHFR polymorphism and psychiatric disorders susceptibility by using random effect models.

Results

We found that MTHFR C677T polymorphism is significantly related to schizophrenia and major depression in the overall population. MTHFR C677T has been linked to an increased risk of bipolar disorder in the recessive model (TT vs. CT + CC). Ethnic subgroup analysis shows that schizophrenia and major depression significantly correlate with MTHFR C677T and A1298C in Asian populations but not Caucasians. Besides, schizophrenia is correlated substantially with MTHFR C677T in the African population. However, the MTHFR A1298C polymorphism is only marginally linked to major depression.

Conclusion

Findings of the current study revealed that MTHFR may contribute to the common pathogenesis of psychiatric diseases and that its variants may be essential in controlling the expression of psychosis-related genes. This study could help the researchers and health specialists in the early diagnosis and treatment of psychiatric disorders.

MTHFR SNPs (Methyl Tetrahydrofolate Reductase, Single Nucleotide Polymorphisms) C677T and A1298C Prevalence and Serum Homocysteine Levels in >2100 Hypofertile Caucasian Male Patients

Methylation is a crucially important ubiquitous biochemical process, which covalently adds methyl groups to a variety of molecular targets. It is the key regulatory process that determines the acquisition of imprinting and epigenetic marks during gametogenesis. Methylation processes are dependent upon two metabolic cycles, the folates and the one-carbon cycles. The activity of these two cycles is compromised by single nucleotide polymorphisms (SNPs) in the gene encoding the Methylenetetrahydrofolate reductase (MTHFR) enzyme. These SNPs affect spermatogenesis and oocyte maturation, creating cytologic/chromosomal anomalies. The two main MTHFR SNP variants C677T (c.6777C>T) and A1298C (c.1298A>C) together with serum homocysteine levels were tested in men with >3 years’ duration of infertility who had failed several ART attempts with the same partner. These patients are often classified as having “idiopathic infertility”. We observed that the genetic status with highest prevalence in this group is the heterozygous C677T, followed by the combined heterozygous C677T/A1298C, and then A1298C; these three variants represent 65% of our population. Only 13.1% of the patients tested are wild type (WT), C677C/A1298A). The homozygous 677TT and the combined heterozygote 677CT/1298AC groups have the highest percentage of patients with an elevated circulating homocysteine level of >15 µMolar (57.8% and 18.8%, respectively, which is highly significant for both). Elevated homocysteine is known to be detrimental to spermatogenesis, and the population with this parameter is not marginal. In conclusion, determination of these two SNPs and serum homocysteine should not be overlooked for patients with severe infertility of long duration, including those with repeated miscarriages. Patients must also be informed about pleiotropic medical implications relevant to their own health, as well as to the health of future children.

Effects of polymorphisms in the MTHFR gene on 5-FU hematological toxicity and efficacy in Thai colorectal cancer patients

Background

The two common methylenetetrahydrofolate reductase (MTHFR) polymorphisms 677G>A and 1298A>C may have been affecting 5-FU toxicity in cancer patients for decades. Drug efficacy has also been shown by previous studies to be affected. In this study, we investigated the effects of these polymorphisms on 5-FU hematological toxicity and treatment efficacy, to provide enhanced pharmacological treatment for cancer patients.

Methods

This is a retrospective study involving 52 Thai colorectal cancer patients who were treated with 5-FU based therapy, using TaqMAN real-time PCR to genotype the MTHFR polymorphisms (677G>A and 1298A>C). The toxicity and response rate were assessed using standardized measures.

Results

Neutropenia was significantly more likely to be experienced (P=0.049, OR=7.286, 95% CI=0.697-76.181) by patients with the MTHFR 677G>A polymorphism, in the same way as leukopenia (P =0.036, OR=3.333, 95%CI=2.183-5.090) and thrombocytopenia (P<0.001, OR=3.917, 95%CI=2.404-6.382). The MTHFR 1298A>C polymorphism had no statistical association with hematological toxicity in 5-FU treatment. The response rate to 5-FU was not significantly affected by these two polymorphisms.

Conclusion

The MTHFR polymorphism 677G>A is a significant risk factor for developing leukopenia, neutropenia and thrombocytopenia as toxic effects of 5-FU therapy in cancer patients. Therefore, patients receiving 5-FU-based therapy should be aware of their polymorphisms as one risk factor for experiencing severe toxicity.

Methylene-tetrahydrofolate reductase gene C677T and A1298C polymorphisms as a risk factor for Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a deadly viral disease. Methylene-tetrahydrofolate reductase (MTHFR) has an important role in folate metabolism, and also in the formation of new cells, DNA synthesis, repair and methylation. We aimed to examine the relationship between MTHFR gene C677T (Ala222Val, rs1801133) and A1298C (Glu429Ala, rs1801131) polymorphisms with CCHF in a Turkish population. Totally 273 participants were included in the current study. One hundred forty-one participants were CCHF patients and one hundred thirty-two participants were healthy controls. The polymerase chain reaction (PCR) and further restriction fragment length polymorphism (RFLP) assays were applied to determine the genotypes of MTHFR polymorphisms. We did not find any differences between the CCHF patients and healthy controls in terms of allele and genotype distributions of both the C677T and A1298C polymorphisms. In composite genotype analysis between different groups, the frequency of CT-AA composite genotype, which is formed by C677T-A1298C polymorphisms, was found to be significantly higher in Mild CCHF patients compared to both Severe CCHF patients and controls (p = 0.036 and p = 0.008, respectively). In conclusion, in this study, we found a relationship between CCHF and MTHFR gene polymorphisms. CT-AA composite genotype of MTHFR gene C677T and A1298C polymorphisms showed a predisposition to Mild CCHF.

Synthesis of genetic association studies on autism spectrum disorders using a genetic model-free approach

BACKGROUND

Autism spectrum disorder (ASD) is a clinically and genetically heterogeneous group of neurodevelopmental disorders. Despite the extensive efforts of scientists, the etiology of ASD is far from completely elucidated. In an effort to enlighten the genetic architecture of ASDs, a meta-analysis of all available genetic association studies (GAS) was conducted.

METHODS

We searched in the Human Genome Epidemiology Navigator (HuGE Navigator) and PubMed for available case-control GAS of ASDs. The threshold for meta-analysis was two studies per genetic variant. The association between genotype distribution and ASDs was examined using the generalized linear odds ratio (ORG). For variants with available allele frequencies, the examined model was the allele contrast.

RESULTS

Overall, 57 candidate genes and 128 polymorphisms were investigated in 159 articles. In total 28 genetic polymorphisms have been shown to be associated with ASDs, that are harbored in 19 genes. Statistically significant results were revealed for the variants of the following genes adenosine deaminase (ADA), bone marrow stromal cell antigen-1 (CD157/BST1), Dopamine receptor D1 (DRD1), engrailed homolog 2 (EN2), met proto-oncogene (MET), methylenetetrahydrofolate reductase (MTHFR), solute carrier family 6 member 4 (SLC6A4), Synaptosomal-associated protein, 25kDa (SNAP-25) and vitamin D receptor (VDR). In the allele contrast model of cases versus healthy controls, significant associations were observed for Adrenoceptor Alpha 1B (ADRA1B), acetyl serotonin O - methyltransferase (ASMT), complement component 4B (C4B), dopamine receptor D3 (DRD3), met proto-oncogene (MET), neuroligin 4, X-linked (NLGN4), neurexin 1 (NRXN1), oxytocin receptor (OXTR), Serine/Threonine-Protein Kinase PFTAIRE-1 (PFTK1), Reelin (RELN) and Ras-like without CAAX 2 (RIT2).

CONCLUSION

These significant findings provide further evidence for genetic factors' implication in ASDs offering new perspectives in means of prevention and prognosis.

Association between Genetic Polymorphisms in Methylenetetrahydrofolate Reductase and Risk of Autoimmune Diseases: A Systematic Review and Meta-Analysis

Methylenetetrahydrofolate reductase (MTHFR) is a critical rate-limiting enzyme in the homocysteine/methionine metabolism pathway that is implicated in the pathogenesis and progression of autoimmune diseases. Previous association studies have been performed to investigate the effect of polymorphisms in MTHFR on the risk of autoimmune diseases with inconsistent results. Therefore, this meta-analysis was designed to assess the association between the MTHFR 677 C/T and 1298 A/C polymorphisms and the susceptibility to autoimmune diseases. We identified reports by a literature search in the following electronic databases: PubMed, Ovid, Web of science, and China National Knowledge Infrastructure. Statistical analyses of the summary odds ratios (ORs) and 95% confidence intervals (CIs) were done using STATA software. In a recessive genetic model, the MTHFR 677 C/T polymorphism was associated with an increased risk of Behcet's disease (OR = 1.97, 95% CI, 1.31-2.97), multiple sclerosis (OR = 1.57, 95% CI, 1.03-2.38), and ankylosing spondylitis (OR = 2.90, 95% CI, 1.92-4.38). The MTHFR 1298 A/C polymorphism was associated an increased risk of multiple sclerosis in a heterozygote comparison (OR = 2.36, 95% CI, 1.29-4.30) and in a dominant model (OR = 2.31, 95% CI, 1.24-4.29). This meta-analysis demonstrated that the MTHFR 677 C/T was a risk factor for Behcet's disease, multiple sclerosis, and ankylosing spondylitis, and the 1298 A/C was a risk factor for multiple sclerosis.

Genetic polymorphisms and gene expression of one-carbon metabolizing enzymes and their relation to breast cancer

Background

Breast cancer is considered the leading cause of cancer-related death among Egyptian women (15.41%). One of the common BC risk factors is the genetic factor. One-carbon metabolism is one of the pathways reported to increase BC risk by influencing DNA synthesis and methylation. Methyl tetrahydrofolate reductase (MTHFR), thymidylate synthase (TYMS) and DNA methyltransferase (DNMT) enzymes are key enzymes in one-carbon metabolism directly and through influencing folate metabolism. We aimed to study the association of the gene expression level and polymorphisms of MTHER C677T (rs1801133), TYMS (rs45445694), TYMS 3′UTR 1494del6 and ΔDNMT3B − 149C>T with breast cancer risk in a sample of Egyptian women.

Methods

This study was conducted on one hundred female breast cancer patients. Genotyping and gene expression of the MTHFR and TYMS (1494del6, rs45445694) and DNMT3B genes were performed.

Results

There was no significant difference (OR 1.493; 95% CI 0.78–2.84; P = 0.288) in the frequency of the MTHFR (C677T) genotypes between breast cancer patients and control subjects and no significant difference in the frequency of the MTHFR mutant T allele. TYMS tandem repeats showed a significant difference (OR 2.232; CI 1.21–4.12; P = 0.01) in the frequency of the genotype 2R/3R among breast cancer patients and control subjects; however, the frequency of the 2R allele was not significantly different from that of the 3R allele (OR 1.461; 95% CI 0.96–2.21; P = 0.073). TYMS 3′-UTR 1494del6 showed a significant difference in the distribution of (+ 6/ + 6), (+ 6/− 6) and (− 6/− 6) genotypes between the patient and control groups (P ≤ 0.001*), and its corresponding mutant allele showed P value ≤ 0.001, 95% CI = 1.64–3.76 and OR = 2.483. The expression of MTHFR was downregulated by 0.62-fold in all malignant tissues compared to normal adjacent tissues (0.57 ± 0.20, P < 0.001*). On the other hand, no significant difference (P = 0.143) in the expression level of TYMS was found. Gene expression of DNMT3B was upregulated by 1.65-fold in all breast cancerous tissue samples compared with the control normal adjacent tissue with mean ± SD of 1.81 ± 0.63. (P ≤ 0.001*).

Conclusion

The current study showed that the 2R/3R TYMS allele and DNMT3B (− 149C>T) SNP are associated with a high risk of breast cancer and that there is a correlation between the 3′-UTR 1494del6 polymorphism (genotype − 6/− 6) and breast cancer risk. A significant reduction was found in the MTHFR gene expression level in BC compared with control tissues, and the DNMT3B (− 149C>T) SNP did affect the DNMT3B expression level.

Update meta-analysis from biomedical literature about MTHFR'polymorphisms and the CML' risk

BACKGROUND

The MTHFR gene polymorphisms are closely related to the chronic myeloid leukemia (CML). Case-control studies have associated the MTHFR polymorphisms and susceptibility to CML but the results were not conclusive.

AIM

To assess this association through an update meta-analysis.

METHODS

A descriptive and qualitative study was conducted among students in the 6th year of the faculty during the academic year 2020/2021. The data were collected through a questionnaire written in french evaluating the teaching methods. A focus group of ten persons was led to understand better student's opinions.

RESULTS

Totally, 17 and 12 case-control studies including CML cases and controls were enrolled in the meta-analysis respectively for C677T and A1298C polymorphism and CML risk. A poor association between the C677T (T vs C ; OR= 1,28; IC95%= [1,01;1,63]; p=0,04) and the one not significant between the A1298C (C vs A ; OR= 1,52; IC95%= [0,92; 2,51]; p= 0,1) polymorphisms and the CML risk for overall population were found.

CONCLUSION

The results of this meta-analysis suggested no significant association between C677T and A1298C polymorphisms and CML risk leading to consider other factors such us folic acid intake, gene-gene and gene- environment interactions.

Association of Fetal MTHFR C677T Polymorphism with Susceptibility to Neural Tube Defects: A Systematic Review and Update Meta-Analysis

Background MTHFR gene may be a key epigenetic regulation-related factor crucial during embryogenesis. We performed a meta-analysis to determine the association of fetal MTHFR C677T polymorphism with neural tube defects (NTDs).Methods A comprehensive literature search of the PubMed, Embase, and CNKI database was performed up to April 10, 2020.Results A total of 19 case-control studies with 2,228 NTDs cases and 4,220 controls were identified. Pooled data revealed that the fetal MTHFR C677T polymorphism was significantly highly correlated with development of NTDs in the overall population. Stratified analysis showed a significant association among Caucasians and Asians, but not in mixed populations. There was a significant association between the MTHFR C677T polymorphism and spina bifida risk. No publication bias was found under any genetic model.Conclusions Our pooled data support the fetal MTHFR C677T polymorphism association with risk of NTDs, especially among Caucasians and Asians.

Folate metabolism abnormalities in infertile patients with endometriosis

Background: Homocysteine levels can be impacted by enzymes variations. Aim: To correlate MTHFR, MTR and MTRR variants with homocysteine levels in the blood and follicular fluid and assisted reproduction results. Material & methods: MTHFR (rs2274976, rs1801131, rs1801133), MTR (rs1805087) and MTRR (rs1801394) genotyping was performed by TaqMan assays and compared with homocysteine levels, measured by ELISA, to oocytes retrieved and to the pregnancy status of women with endometriosis and controls. Results: The MTR G allele and GG genotype were more common in patients with endometriosis. They also showed lower levels of homocysteine and more clinical gestations. Epistasis analysis showed a model associated with gestational results, composed of MTHFR+MTR variants (CC+AG). Conclusion: The summation effect of variants in genes participating in folate metabolism was associated with pregnancy status in Brazilian women. MTR variants were more observed in endometriosis patients, as well as lower follicular Hcy levels and increased clinical pregnancy results.

Genetic and Epigenetic Studies in Nonsyndromic Oral Clefts

The etiology of non-syndromic oral clefts (NSOFC) is complex with genetics, genomics, epigenetics and stochastics factors playing a role. Several approaches have been applied to understand the etiology of non-syndromic oral clefts. These include linkage, candidate gene association studies, genome-wide association studies, whole genome sequencing, copy number variations and epigenetics. In this review we shared these approaches, genes and loci reported in some studies.

Association between Fetal MTHFR A1298C (rs1801131) Polymorphism and Neural Tube Defects Risk: A Systematic Review and Meta-Analysis

BACKGROUND

The association of the fetal MTHFR A1298C (rs1801131) polymorphism and neural tube defects (NTDs) susceptibility has been widely demonstrated, but the results remain inconclusive. Thus, we performed a meta-analysis to investigate the association between fetal MTHFR A1298C polymorphism and NTDs risk.

METHODS

An electronic search of PubMed, web of science, SciELO, CNKI database for studies on the fetal MTHFR A1298C polymorphism and NTDs risk was performed up to March 30, 2020.

RESULTS

A total of 22 case-control studies with 3,224 fetuses with NTDs and 3,295 controls were selected. Overall, pooled data showed that the fetal MTHFR A1298C polymorphism was not significantly associated with risk an increased risk of NTDs in the global population. When stratified analysis by ethnicity, country of origin and NTDs type, still no statistically significant association was found.

CONCLUSIONS

Our pooled data emerged no evidence for significant association between fetal MTHFR A1298C polymorphism and NTDs risk.

Folic Acid, Folinic Acid, 5 Methyl TetraHydroFolate Supplementation for Mutations That Affect Epigenesis through the Folate and One-Carbon Cycles

Methylation is an essential biochemical mechanism that is central to the transmission of life, and crucially responsible for regulating gametogenesis and continued embryo development. The methylation of DNA and histones drives cell division and regulation of gene expression through epigenesis and imprinting. Brain development and its maturation also depend on correct lipid methylation, and continued neuronal function depends on biogenic amines that require methylation for their synthesis. All methylation processes are carried out via a methyltransferase enzyme and its unique co-factor S-adenosylmethionine (SAM); the transfer of a methyl group to a target molecule results in the release of SAH (SA homocysteine), and then homocysteine (Hcy). Both of these molecules are toxic, inhibiting methylation in a variety of ways, and Hcy recycling to methionine is imperative; this is achieved via the one carbon cycle, supported by the folates cycle. Folate deficiency causes hyperhomocysteinaemia, with several associated diseases; during early pregnancy, deficiency interferes with closure of the neural tube at the fourth week of gestation, and nutraceutical supplementation has been routinely prescribed to prevent neural tube defects, mainly involving B vitamins, Zn and folates. The two metabolic pathways are subject to single nucleotide polymorphisms that alter their activity/capacity, often severely, impairing specific physiological functions including fertility, brain and cardiac function. The impact of three types of nutraceutical supplements, folic acid (FA), folinic acid (FLA) and 5 Methyl THF (MTHF), will be discussed here, with their positive effects alongside potentially hazardous secondary effects. The issue surrounding FA and its association with UMFA (unmetabolized folic acid) syndrome is now a matter of concern, as UMFA is currently found in the umbilical cord of the fetus, and even in infants’ blood. We will discuss its putative role in influencing the acquisition of epigenetic marks in the germline, acquired during embryogenesis, as well as the role of FA in the management of cancerous disease.

Pharmacogenetics of Drug Therapies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disorder that can lead to severe joint damage and is often associated with a high morbidity and disability. Disease-modifying anti-rheumatic drugs (DMARDs) are the mainstay of treatment in RA. DMARDs not only relieve the clinical signs and symptoms of RA but also inhibit the radiographic progression of disease and reduce the effects of chronic systemic inflammation. Since the introduction of biologic DMARDs in the late 1990s, the therapeutic range of options for the management of RA has significantly expanded. However, patients' response to these agents is not uniform with considerable variability in both efficacy and toxicity. There are no reliable means of predicting an individual patient's response to a given DMARD prior to initiation of therapy. In this chapter, the current published literature on the pharmacogenetics of traditional DMARDS and the newer biologic DMARDs in RA is highlighted. Pharmacogenetics may help individualize drug therapy in patients with RA by providing reliable biomarkers to predict medication toxicity and efficacy.

Genetic Variants Associated With Resilience in Human and Animal Studies

Resilience is broadly defined as the ability to maintain or regain functioning in the face of adversity and is influenced by both environmental and genetic factors. The identification of specific genetic factors and their biological pathways underpinning resilient functioning can help in the identification of common key factors, but heterogeneities in the operationalisation of resilience have hampered advances. We conducted a systematic review of genetic variants associated with resilience to enable the identification of general resilience mechanisms. We adopted broad inclusion criteria for the definition of resilience to capture both human and animal model studies, which use a wide range of resilience definitions and measure very different outcomes. Analyzing 158 studies, we found 71 candidate genes associated with resilience. OPRM1 (Opioid receptor mu 1), NPY (neuropeptide Y), CACNA1C (calcium voltage-gated channel subunit alpha1 C), DCC (deleted in colorectal carcinoma), and FKBP5 (FKBP prolyl isomerase 5) had both animal and human variants associated with resilience, supporting the idea of shared biological pathways. Further, for OPRM1, OXTR (oxytocin receptor), CRHR1 (corticotropin-releasing hormone receptor 1), COMT (catechol-O-methyltransferase), BDNF (brain-derived neurotrophic factor), APOE (apolipoprotein E), and SLC6A4 (solute carrier family 6 member 4), the same allele was associated with resilience across divergent resilience definitions, which suggests these genes may therefore provide a starting point for further research examining commonality in resilience pathways.