Polymorphisms involved in the folate metabolizing pathway and risk of multiple myeloma

The relationship between methionine synthase rs1805087 polymorphism and hematological cancers risk

Background: The relationship between hematological cancer susceptibility and methionine synthase MTR A2756G (rs1805087) polymorphism is inconclusive based on data from past studies. Hence, this updated meta-analysis was conducted to investigate the relationship between methionine synthase reductase (MTR) rs1805087 polymorphism and hematological cancers. Method: We searched EMBASE, Google Scholar, Ovid and PubMed databases for possible relevant articles up to December 31, 2019. Results: The overall pooled outcome of our analysis showed lack of association between the risk of hematological malignancies and MTR A2756G polymorphism under the allele model (G vs A: odds ratio = 1.001, 95% CI: 0.944-1.061; p = 0.983), recessive model (GG vs GA + AA: odds ratio = 1.050, 95% CI: 0.942-1.170; p = 0.382). Conclusion: The findings in this study demonstrate a lack of relationship between hematological cancers and MTR A2756G.

Association of Genetic Variants with Hyperhomocysteinemia in Indian Patients with Thrombosis

Hyperhomocysteinemia known to be associated with increased thrombotic tendency has been considered as a risk factor for coronary artery disease, atherosclerosis, venous thrombosis, and stroke. There are three main genes MTHFR, cystathionine beta-synthase (CBS) and methionine synthase (MS) and it's genetic variant that are known to influence the homocysteine metabolism leading to hyperhomocysteinemia. There is scarcity of Indian data on hyperhomocysteinemia and genetics variants in patients with thrombosis. Hence the objective of present study was to determine MTHFR, CBS, and MS genetic variants in thrombosis patients from Indian population. Genetic variant analysis was performed on thrombosis patients to detect MTHFR C677T (rs1801133), MTHFR A1298C (rs1801131), MS A2756G (rs1805087) and CBS T833C (rs5742905) mutations. The mutant allele frequencies of MTHFR 677T, MTHFR 1298C, MS2756G and CBS 833C were observed to be 16.1%, 37.5%, 34.1% and 5.8% respectively. MTHFR 677TT genotype was observed to be significantly associated with elevated homocysteine (Hcy) levels (64.65 μmol/L) alleles as compared to CC alleles (32.43 μmol/L) and CT alleles (30.54 μmol/L). MTHFR A1298C, MS A2756G and CBS T833C genotypes did not showed significant association with higher Hcy levels. Thus, in Indian patients with thrombosis only MTHFR T677T genotype was observed to be significantly associated with hyperhomocysteinemia.

The association between methionine synthase A2756G polymorphism and hematological cancer: A meta-analysis

BACKGROUND

Numerous studies have focused on the association of methionine synthase (MS) A2756G polymorphism and acute hematological cancer risk. However, the results remain inconsistent. Therefore, a meta-analysis was performed to derive a more precise estimate of the association between them.

METHODS

This meta-analysis involved 25 articles (26 studies) including 8641 hematological cancer patients and 15,498 controls. The pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) of the association between MS A2756G polymorphism and the risk of hematological cancer were calculated.

RESULTS

Overall, no significant increased risks were found between MS A2756G polymorphism and hematological cancer risk under allelic homozygote (GA vs AA: OR = 0.98, 95% CI = 0.89-1.07, P = .62), heterozygote (GG vs AA: OR = 0.99, 95% CI = 0.85-1.15, P = .91), dominant (AG+GG vs AA: OR = 0.99, 95% CI = 0.90-1.08, P = .93), and recessive (GG vs AG+AA: OR = 1.00, 95% CI = 0.86-1.16, P = .97) models, respectively. In the stratified analyses by ethnicity and source of controls, there were still no significant associations between them in all genetic models.

CONCLUSIONS

Therefore, these findings demonstrate that MS A2756G polymorphism may not be a risk factor for hematological cancer.

Association of MTRR A66G polymorphism with cancer susceptibility: Evidence from 85 studies

Methionine synthase reductase (MTRR) is a key regulatory enzyme involved in the folate metabolic pathway. Previous studies investigating the association of MTRR A66G polymorphism with cancer susceptibility reported inconclusive results. We performed the current meta-analysis to obtain a more precise estimation of the possible association. Published literatures were identified from PubMed, Embase and CBM databases up to October 2016. The strength of the association between the MTRR A66G polymorphism and cancer susceptibility was assessed using odds ratios (ORs) and the corresponding 95% confidence intervals (CIs). Eighty five published studies with 32,272 cases and 37,427 controls were included in this meta-analysis. Pooled results indicated that the MTRR A66G polymorphism was associated with an increased overall cancer risk (homozygous model: OR = 1.08, 95% CI = 1.02-1.15, P = 0.009; recessive model: OR = 1.06, 95% CI = 1.00-1.12, P < 0.001 and allele comparison: OR = 1.03, 95% CI = 1.00-1.06, P < 0.001). Stratification analysis further indicated significant associations in head and neck cancer, Caucasians, Africans, and high quality studies. However, to avoid the "false-positive report", the significant findings were assessed by the false-positive report probability (FPRP) test. Interestingly, the results of FPRP test revealed that the increased risk for MTRR A66G polymorphism among Africans need further validation due to the high probabilities of false-positive results. This meta-analysis suggests that the MTRR A66G polymorphism is associated with significantly increased cancer risk, a finding that needs to be confirmed in single large studies.

A Mendelian Randomization Study of Plasma Homocysteine and Multiple Myeloma

Observational studies have demonstrated an association between elevated homocysteine (Hcy) level and risk of multiple myeloma (MM). However, it remains unclear whether this relationship is causal. We conducted a Mendelian randomization (MR) study to evaluate whether genetically increased Hcy level influences the risk of MM. We used the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism as an instrumental variable, which affects the plasma Hcy levels. Estimate of its effect on plasma Hcy level was based on a recent genome-wide meta-analysis of 44,147 individuals, while estimate of its effect on MM risk was obtained through meta-analysis of case-control studies with 2,092 cases and 4,954 controls. By combining these two estimates, we found that per one standard-deviation (SD) increase in natural log-transformed plasma Hcy levels conferred a 2.67-fold increase in risk for MM (95% confidence interval (CI): 1.12–6.38; P = 2.7 × 10⁻²). Our study suggests that elevated Hcy levels are causally associated with an increased risk of developing MM. Whether Hcy-lowering therapy can prevent MM merits further investigation in long-term randomized controlled trials (RCTs).

Meta-analysis of the association of MTHFR polymorphisms with multiple myeloma risk

The association of methylenetetrahydrofolate reductase (MTHFR) polymorphisms with multiple myeloma (MM) risk has been explored, but the results remain controversial. Thus, a meta-analysis was performed to provide a comprehensively estimate. The case-control studies about MTHFR C677T and A1298C polymorphisms with MM risk were collected by searching PubMed, Elsevier, China National Knowledge Infrastructure and Wanfang Databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were applied to assess the strength of association. Overall, no significant association was found between MTHFR A1298C polymorphism and MM risk under all four genetic models (AC vs. AA, OR = 0.99, 95%CI = 0.82-1.20; CC vs. AA, OR = 1.14, 95%CI = 0.77-1.68; recessive model, OR = 1.10, 95%CI = 0.76-1.59; dominant model, OR = 1.01, 95%CI = 0.84-1.22). The risk was also not significantly altered for C677T polymorphism and MM in overall comparisons (CT vs. CC, OR = 1.04, 95%CI = 0.93-1.17; TT vs. CC, OR = 1.16, 95%CI = 0.98-1.37; recessive model, OR = 1.13, 95%CI = 0.98-1.32; dominant model, OR = 1.07, 95%CI = 0.96-1.20). In subgroup analyses by ethnicity, no significant association was observed in both Caucasians and Asians. This meta-analysis suggested that MTHFR polymorphisms were not associated with MM risk.

The methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and tumor risk: evidence from 134 case-control studies

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism, which is essential for DNA synthesis and methylation. Genetic variations in the MTHFR gene seem to contribute to a decreased activity of MTHFR, ultimately confer increased susceptibility to cancer. As the most extensively studied polymorphism, MTHFR C677T polymorphism was shown to contribute to cancer susceptibility but the results were inconsistent. The authors performed a meta-analysis including 134 studies (46,207 cases and 69,160 controls) to address the issue. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to assess the association. Overall, a significant elevated risk of cancer was associated with the MTHFR C677T polymorphism in T-allele versus C-allele comparison (OR = 1.06, 95% CI 1.02-1.11, P(heterogeneity) < 0.001), homozygote model (OR = 1.08, 95% CI 1.01-1.17, P(heterogeneity) < 0.001) and dominant model (OR = 1.05, 95% CI 1.00-1.10, P(heterogeneity) < 0.001). In the stratified analyses, significantly increased cancer risks were indicated among Asians in all genetic models except for heterozygote model. Further analysis revealed that C677T was significantly associated with an increased risk of esophageal and stomach cancer. This meta-analysis supports an association between the MTHFR C677T polymorphism and increased risk of esophageal and stomach cancer, especially among Asians. Additionally, more high-quality studies and that the covariates responsible for heterogeneity should be controlled to obtain a more conclusive response about the function of MTHFR C677T in cancer.

The association between two polymorphisms in the TS gene and risk of cancer: a systematic review and pooled analysis

Thymidylate synthase (TS) is an important enzyme involved in folate metabolism and catalyzes methylation of deoxyuridine monophosphate to deoxythymidine monophosphate, which is essential for DNA replication. Thymidylate synthase enhancer region (TSER) and TS1494del6, two functionally important and ethnically diverse polymorphisms mapping to its gene region, are the most extensively studied. Considering the potential influence of altering TS activity, it is plausible that TS polymorphisms might play a role in the development of cancer. Although the effects of TS polymorphisms on susceptibility to human cancer have been investigated in many studies, the results remain conflicting rather than conclusive. To resolve these conflicts, we performed a quantitative synthesis of the evidence on the association between these two polymorphisms and cancer risk, including 63 studies (19,707 cases and 27,398 controls) for TSER polymorphism and 39 studies (13,489 cases and 16,297 controls) for TS1494del6 polymorphism. Our meta-analysis suggested that these two polymorphisms are not associated with cancer risk when all studies were pooled together. In the stratified analyses, we found that individuals with 2R/2R genotype had a significantly higher cancer risks among Asians (2R/2R vs. 3R/3R: odds ratio [OR] = 1.24, 95% confidence interval (95% CI) = 1.05-1.45; recessive model: OR = 1.23, 95% CI = 1.05-1.44). Further analyses revealed that 2R/2R genotype was significantly associated with an increased risk of gastroesophageal cancer among Asians, whereas it might provide protecting effects against colorectal cancer risk in a dominant genetic model for Caucasians. Additionally, TS1494del6 polymorphism may contribute to genetic susceptibility of breast cancer among Asians.

Thymidylate synthase polymorphisms and hematological cancer risk: a meta-analysis

Previous studies on the association of Thymidylate synthase (TYMS) polymorphisms with risk of hematological malignancies have produced conflicting results. The purpose of this meta-analysis was to define the effect of TYMS 5'-untranslated enhanced region (TSER) and 3'-untranslated region (TS3'-UTR) polymorphisms on the risk of hematological malignancies. Seventeen articles were identified as eligible in the case of TSER (2R > 3R) polymorphism (4511 cases and 6113 controls) and seven articles in the case of TS3'-UTR (1494del6) polymorphism (2721 cases and 3761 controls). The overall results suggested that either TSER or TS3'-UTR polymorphism was not associated with the risk of hematological malignancies. In stratified analyses, significantly decreased acute lymphoblastic leukemia (ALL) risk was found in adults (2R/3R vs. 2R/2R: odds ratio [OR] = 0.64, 95% confidence interval [CI]: 0.43-0.97), but increased ALL risk was observed in children (3R/3R vs. 2R/2R: OR = 1.46, 95% CI: 1.03-2.06). Increased non-Hodgkin lymphoma risk was found in the Caucasian population (2R/3R vs. 2R/2R: OR = 1.31, 95% CI: 1.10-1.56). Protective effects of the TS3'-UTR polymorphism (-6 bp/-6 bp) on hematological malignancies were found in a homozygote model and recessive model when the source of controls was stratified as hospital based. In conclusion, the TYMS TSER polymorphism may contribute to a susceptibility to risk of ALL in children and non-Hodgkin lymphoma in Caucasians, but protection from ALL risk in adults. The TS3'-UTR polymorphism (-6 bp/-6 bp) may have a protective effect in hematological malignancies.

MyelomA Genetics International Consortium

While the etiology of multiple myeloma (MM) is largely unknown, evidence for an inherited genetic susceptibility is provided by the two-fold increased risk of the disease seen in first-degree relatives of cases of MM. It is likely that part of this heritable risk is a consequence of the co-inheritance of low-risk genetic variants. The accumulated experience to date in identifying risk variants for other tumors has highlighted difficulties in conducting statistically and methodologically rigorous studies. The MyelomA Genetics International Consortium (MAGIC) includes 16 research groups in Europe, Asia, Australasia, the Middle East and the Americas engaged in studying the genetics of MM. The first goal of MAGIC is to identify and characterize common genetic variants for MM through association-based analyses. Here, we review the rationale for identifying genetic risk variants for MM and our proposed strategy for establishing MAGIC.

Genetic variations in multiple myeloma I: effect on risk of multiple myeloma

Few risk factors have been established for the plasma cell disorder multiple myeloma, but some of these like African American ethnicity and a family history of B-cell lymphoproliferative diseases suggest a genetic component for the disease. Genetic variation represents the genetic basis of variability in a population. The complex interplay between environment and genes for the development of cancer may therefore be influenced by genetic variations. A genetic variation may change the function of the gene, and if the genetic variation is associated with the risk of disease, that particular gene may be involved in the pathogenesis of disease. Genes of interest are genes involved in the normal development and function of the plasma cell and genes that protect us against exposures from the environment, for example, genes involved in the metabolism of xenobiotics, metabolism of folate and methionine, as well as genes involved in inflammation and DNA repair. Identification of genes with potential influence on cancer risk may help us to establish relevant laboratory studies on exposure and dose-response assessment and may help us to test the hypothesis in epidemiological studies. Knowledge of individual at high risk of cancer may offer promising insight for the prevention of cancer.

Methionine synthase reductase A66G polymorphism contributes to tumor susceptibility: evidence from 35 case-control studies

Methionine synthase reductase (MTRR) gene is involved in tumorigenesis by regulating DNA methylation through activation of methionine synthase (MTR). MTRR is polymorphic at nucleotide 66 (A-to-G) and the resulting variant enzyme has a lower affinity for MTR. The reported associations of MTRR A66G polymorphism with cancer risk are contradictory. Therefore, we performed a meta-analysis to better assess the associations, including 18,661 cases and 27,678 controls from 35 studies. Crude ORs with 95% CIs were used to assess the strength of association between the MTRR A66G polymorphism and cancer risk. The pooled ORs were performed for homozygote model (GG vs. AA), heterozygote model (GG vs. GA), recessive genetic model (GG vs. GA + AA), and dominant genetic model (GG + GA vs. AA), respectively. Overall, results indicated that the G allele and GG variant genotypes were associated with a significantly increased cancer risk (G vs. A: OR, 1.039; 95% CI, 1.009-1.078; homozygote model: OR, 1.094; 95% CI, 1.006-1.191). In subgroup analysis by ethnicity, significant increased risks were found among Asians with G allele (G vs. A: OR, 1.063; 95% CI, 1.011-1.119; homozygote model: OR, 1.189; 95% CI, 1.055-1.341; recessive model: OR, 1.197; 95% CI, 1.068-1.341). For stratification analysis, the cancer types with fewer than three studies were categorized into "other cancers", and the results indicated that there was a significant elevated cancer risk in "other cancers" in all genetic models, not in colorectal cancer, lymphoid leukemia or breast cancer. In summary, our study suggests that the MTRR A66G polymorphism is a potential biomarker for cancer risk.

Study of specific genetic and epigenetic variables in multiple myeloma

Few studies have examined the association between methylenetetrahydrofolate reductase (MTHFR) SNPs, epigenetic changes, and multiple myeloma (MM). We wished to determine genotype distributions for MTHFR 1298AC SNP in cases of MM and healthy controls and to examine whether there is any correlation between the methylation status of the CpG island of CDKN2A and Snk/Plk2 and MTHFR genotypes and with overall survival (OS) and other relevant clinical parameters. Bone marrow and peripheral blood were obtained from 45 patients with MM and 77 controls, respectively. The frequencies of the MTHFR 1298AA, 1298AC, and 1298CC genotypes were 53.3%, 40%, and 6.7% for the patient population and 50.6%, 41.6%, and 7.8% for the controls. No statistically significant difference was found in genotype distribution between cases and controls. No correlation was noted between MTHFR genotypes and OS, disease stage, bone disease, anemia, and extramedullary disease. Regarding CDKN2A and Snk/Plk2 CpG island methylation analysis, we found 12 of 45 patients and 27 of 45, respectively, to be methylated. CDKN2A and Snk/Plk2 methylation did not correlate with MTHFR genotypes. Herein, we report the identification of Snk/Plk2 as a novel methylated gene in MM and show that methylation is not influenced in this CpG island or in that of a previously described methylated gene, CDKN2A, in MM. Further evaluation in a larger sample of patients is needed in order to better define the prognostic and clinical value, if any, of MTHFR 1298 polymorphisms and CDKN2A and Snk/Plk2 methylation in the pathogenesis of MM.

PARP-1 Val762Ala polymorphism is associated with reduced risk of non-Hodgkin lymphoma in Korean males

Background

Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme that plays a role in DNA repair, differentiation, proliferation, and cell death. The polymorphisms of PARP-1 have been associated with the risk of various carcinomas, including breast, lung, and prostate. We investigated whether PARP-1 polymorphisms are associated with the risk of non-Hodgkin lymphoma (NHL).

Methods

Subjects from a Korean population consisting of 573 NHL patients and 721 controls were genotyped for 5 PARP-1 polymorphisms (Asp81Asp, Ala284Ala, Lys352Lys, IVS13+118A>G, and Val762Ala) using High Resolution Melting polymerase chain reaction (PCR) and an automatic sequencer.

Results

None of the 5 polymorphisms were associated with overall risk for NHL. However, the Val762Ala polymorphism was associated with reduced risk for NHL in males [odds ratio (OR), 0.62; 95% confidence interval (CI), 0.41-0.93 for CC genotype and OR, 0.84; 95% CI, 0.60-1.16 for TC genotype] with a trend toward a gene dose effect (p for trend, 0.02). The Asp81Asp (p for trend, 0.04) and Lys352Lys (p for trend, 0.03) polymorphisms revealed the same trend. In an association study of PARP-1 haplotypes, the haplotype-ACAAC was associated with decreased risk of NHL in males (OR, 0.75; 95% CI, 0.59-0.94).

Conclusion

The present data suggest that Val762Ala, Asp81Asp, and Lys352Lys polymorphisms and the haplotype-ACAAC in PARP-1 are associated with reduced risk of NHL in Korean males.

Methionine synthase A2756G polymorphism and cancer risk: a meta-analysis

Polymorphisms in methionine synthase (MTR) gene may be involved in carcinogenesis by affecting DNA methylation. However, association studies on MTR A2756G polymorphism in cancers have reported conflicting results. Therefore we performed a meta-analysis to better assess the associations. A total of 24 896 cancer patients and 33 862 controls from 52 articles for MTR A2756G were investigated. Overall, individuals carrying MTR 2756GG genotype had a subtly reduced cancer risk under a recessive genetic model (odds ratio (OR), 0.92; P=0.053; 95% confidence interval (95% CI), 0.84-1.00; I(2)=0.0%; P(heterogeneity)=0.61). In the subgroup analyses by ethnicity, 2756GG was associated with a significantly reduced cancer risk in European populations (OR, 0.83; P=0.001; 95% CI, 0.74-0.93; I(2)=0.0%; P(heterogeneity)=0.99). However, in Asian populations, a significantly elevated association between 2756GG genotype and cancer risk was observed (OR, 1.33; P=0.012; 95% CI, 1.06-1.65; I(2)=0.0%; P(heterogeneity)=0.50). In studies stratified by tumor site, there was a significantly reduced risk of acute lymphoblastic leukemia (ALL) (OR, 0.54; P=0.049; 95% CI, 0.29-1.00; I(2)=10.7%; P(heterogeneity)=0.33) and colorectal cancer (OR, 0.63; P=0.004; 95% CI, 0.47-0.87; I(2)=0.0%; P(heterogeneity)=0.73) in European populations. Our study indicates that MTR A2756G polymorphism is a candidate gene polymorphism for cancer susceptibility regardless of environmental factors. Large-scale, well-designed, and population-based studies are required to further investigate gene-gene and gene-environment interactions on MTR A2756G polymorphism and tissue-specific cancer risk in an ethnicity-specific population.