Associations between C677T and A1298C polymorphisms of MTHFR and susceptibility to rheumatoid arthritis: a systematic review and meta-analysis

MTHFR c.665C>T and c.1298A>C Polymorphisms in Tailoring Personalized Anti-TNF-α Therapy for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease with a prevalence of 1%. Currently, RA treatment aims to achieve low disease activity or remission. Failure to achieve this goal causes disease progression with a poor prognosis. When treatment with first-line drugs fails, treatment with tumor necrosis factor-α (TNF-α) inhibitors may be prescribed to which many patients do not respond adequately, making the identification of response markers urgent. This study investigated the association of two RA-related genetic polymorphisms, c.665C>T (historically referred to as C677T) and c.1298A>C, in the MTHFR gene as response markers to an anti-TNF-α therapy. A total of 81 patients were enrolled, 60% of whom responded to the therapy. Analyses showed that both polymorphisms were associated with a response to therapy in an allele dose-dependent manner. The association for c.665C>T was significant for a rare genotype (p = 0.01). However, the observed opposite trend of association for c.1298A>C was not significant. An analysis revealed that c.1298A>C, unlike c.665C>T, was also significantly associated with the drug type (p = 0.032). Our preliminary results showed that the genetic polymorphisms in the MTHFR gene were associated with a response to anti-TNF-α therapy, with a potential significance for the anti-TNF-α drug type. This evidence suggests a role for one-carbon metabolism in anti-TNF-α drug efficacy and contributes to further personalized RA interventions.

Methylenetetrahydrofolate (MTHFR), the One-Carbon Cycle, and Cardiovascular Risks

The 5-10-methylenetetrahydrofolate reductase (MTHFR) enzyme is vital for cellular homeostasis due to its key functions in the one-carbon cycle, which include methionine and folate metabolism and protein, DNA, and RNA synthesis. The enzyme is responsible for maintaining methionine and homocysteine (Hcy) balance to prevent cellular dysfunction. Polymorphisms in the MTHFR gene, especially C677T, have been associated with various diseases, including cardiovascular diseases (CVDs), cancer, inflammatory conditions, diabetes, and vascular disorders. The C677T MTHFR polymorphism is thought to be the most common cause of elevated Hcy levels, which is considered an independent risk factor for CVD. This polymorphism results in an amino acid change from alanine to valine, which prevents optimal functioning of the enzyme at temperatures above 37 °C. Many studies have been conducted to determine whether there is an association between the C677T polymorphism and increased risk for CVD. There is much evidence in favour of this association, while several studies have concluded that the polymorphism cannot be used to predict CVD development or progression. This review discusses current research regarding the C677T polymorphism and its relationship with CVD, inflammation, diabetes, and epigenetic regulation and compares the evidence provided for and against the association with CVD.

Genetic Polymorphisms Associated with Rheumatoid Arthritis Development and Antirheumatic Therapy Response

Rheumatoid arthritis (RA) is the most common inflammatory arthropathy worldwide. Possible manifestations of RA can be represented by a wide variability of symptoms, clinical forms, and course options. This multifactorial disease is triggered by a genetic predisposition and environmental factors. Both clinical and genealogical studies have demonstrated disease case accumulation in families. Revealing the impact of candidate gene missense variants on the disease course elucidates understanding of RA molecular pathogenesis. A multivariate genomewide association study (GWAS) based analysis identified the genes and signalling pathways involved in the pathogenesis of the disease. However, these identified RA candidate gene variants only explain 30% of familial disease cases. The genetic causes for a significant proportion of familial RA have not been determined until now. Therefore, it is important to identify RA risk groups in different populations, as well as the possible prognostic value of some genetic variants for disease development, progression, and treatment. Our review has two purposes. First, to summarise the data on RA candidate genes and the increased disease risk associated with these alleles in various populations. Second, to describe how the genetic variants can be used in the selection of drugs for the treatment of RA.

Associations between WNT1-inducible signaling pathway protein-1 (WISP-1) genetic polymorphisms and clinical aspects of rheumatoid arthritis among Chinese Han subjects

This study genotyped blood samples from 214 patients with rheumatoid arthritis (RA) and 293 healthy controls for single nucleotide polymorphisms (SNPs) rs2977537, rs2929970, rs2929973, rs2977530, rs1689334 and rs62514004. We want to investigate whether the SNPs in the WNT1-inducible signaling pathway protein 1 (WISP-1) gene may increase the risk of developing RA. We showed that RA disease was more likely with the AA genotype compared with the AG genotype of SNP rs2977537 (adjusted odds ratio [AOR]: 0.54; 95% confidence interval [CI]: 0.34-0.84), and with the TT genotype (AOR: 0.24; 95% CI: 0.13-0.39) or the GG genotype (AOR: 0.05; 95% CI: 0.03-0.10) compared with the GT genotype of rs2929973, and with the AA genotype (AOR: 0.34; 95% CI: 0.22-0.54) or GG genotype (AOR: 0.52; 95% CI: 0.31 to 0.87) vs the AG genotype of rs2977530. Rheumatoid factor positivity was more likely with the AA genotype than with the AG genotype of the rs2977537 polymorphism (AOR: 0.16; 95% CI: 0.16-0.94). High CRP (>8 mg/L) was more likely with the non-AG genotype (AA + GG) than the AG genotype of rs2977537 (AOR: 1.84; 95% CI: 1.05-3.21) and with the AA genotype vs the AG genotype of rs2977530 (AOR: 2.62; 95% CI: 1.35-5.09). Compared with the AG genotype, the AA genotype of rs2929970 was more likely to require prednisolone (AOR: 0.49; 95% CI: 0.27-0.88), while the AG genotype was more likely than the AA genotype of SNP rs2977530 to require TNF-α inhibitors (AOR: 2.07; 95% CI: 1.08 to 3.98). WISP-1 may be a diagnostic marker and therapeutic target for RA therapy.

Association of Polymorphisms in Genes Involved in One-Carbon Metabolism with MTHFR Methylation Levels

Methylenetetrahydrofolate reductase (MTHFR) is a pivotal enzyme in the one-carbon metabolism, a metabolic pathway required for DNA synthesis and methylation reactions. MTHFR hypermethylation, resulting in reduced gene expression, can contribute to several human disorders, but little is still known about the factors that regulate MTHFR methylation levels. We performed the present study to investigate if common polymorphisms in one-carbon metabolism genes contribute to MTHFR methylation levels. MTHFR methylation was assessed in peripheral blood DNA samples from 206 healthy subjects with methylation-sensitive high-resolution melting (MS-HRM); genotyping was performed for MTHFR 677C>T (rs1801133) and 1298A>C (rs1801131), MTRR 66A>G (rs1801394), MTR 2756A>G (rs1805087), SLC19A1 (RFC1) 80G>A (rs1051266), TYMS 28-bp tandem repeats (rs34743033) and 1494 6-bp ins/del (rs34489327), DNMT3A -448A>G (rs1550117), and DNMT3B -149C>T (rs2424913) polymorphisms. We observed a statistically significant effect of the DNMT3B -149C>T polymorphism on mean MTHFR methylation levels, and particularly CT and TT carriers showed increased methylation levels than CC carriers. The present study revealed an association between a functional polymorphism of DNMT3B and MTHFR methylation levels that could be of relevance in those disorders, such as inborn defects, metabolic disorders and cancer, that have been linked to impaired DNA methylation.

The thymidylate synthase enhancer region (TSER) polymorphism increases the risk of thymic lymphoid hyperplasia in patients with Myasthenia Gravis

BACKGROUND

Myasthenia Gravis (MG) is caused, in approximately 80% of the patients, by autoantibodies against the nicotinic acetylcholine receptor (AChR). The disease is often associated with pathological changes of the thymus: thymic epithelial tumours are present in about 10-20% of the patients, while up to 80% of the patients with early disease onset have thymic hyperplasia. Folate metabolism is required for the production of DNA precursors and for proper DNA methylation reactions, and impaired folate metabolism has been often associated with cellular growth and cancer.

METHODS

We investigated if major polymorphisms of folate-related genes, namely MTHFR c.677C>T, MTR c.2756A>G, MTRR c.66A>G and TYMS TSER (a 28-bp tandem repeat in the 5' promoter enhancer region of TYMS) increase the risk of pathological changes of the thymus in AChR+ MG patients. A total of 526 AChR+ MG patients, including 132 patients with normal (involuted) thymus, 146 patients with thymic hyperplasia, and 248 patients with a thymoma were included in the study. Allele and genotype comparisons were performed among the three study groups, after correcting for multiple testing.

RESULTS

The frequency of the TYMS TSER 3R allele was significantly higher in MG patients with thymic hyperplasia (P=0.004), and the TYMS TSER 3R3R genotype was significantly associated with increased risk of thymic hyperplasia [OR 2.71 (95% CI: 1.34-5.47)].

CONCLUSIONS

The 3R allele in the thymidylate synthase promoter enhancer region results in increased protein production, required for the synthesis of DNA precursors. The present study suggests that the TYMS TSER 3R allele increases the risk of thymic lymphoid hyperplasia in AChR+ MG patients.

Opposite impact of Methylene tetrahydrofolate reductase C677T and Methylene tetrahydrofolate reductase A1298C gene polymorphisms on systemic inflammation

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms have been found to be related with many diseases. Systemic inflammation is now considered as a major predisposition factor for diseases including diabetes mellitus (DM), coronary arterial disease (CAD), stroke, and cancer. This study aimed to investigate whether systemic inflammation is a possible underlying pathogenesis for MTHFR gene polymorphism-related disease.

METHODS

A total of 292 patients were enrolled, and single nucleotide polymorphisms for MTHFR C667T and A1298C were genotyped. Systemic inflammation markers, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) were collected.

RESULTS

In our study population, MTHFR 677 variants had significant higher NLR level than MTHFR 677 wild type (3.77 ± 0.26 vs 3.06 ± 0.18, P = .028). Logistic regression analysis showed that MTHFR 677 variants were significantly associated with increased NLR level. MTHFR 1298 variants showed the opposite effects which tended to have lower level of NLR (3.21 ± 0.16 vs 3.79 ± 0.34, P = .087) and PLR (137.0 ± 4.8 vs 157.7 ± 9.4, P = .052) than MTHFR 1298 wild type. General linear model showed that there was no statistically significant interaction between MTHFR C667T and A1298C gene polymorphism on NLR or PLR.

CONCLUSIONS

This study indicates that MTHFR C677T and MTHFR A1298C gene polymorphisms have opposite effect on systemic inflammation, and systemic inflammation may contribute to the pathogenesis for diseases associated with MTHFR C667T gene polymorphism.