Folate pathway gene polymorphisms, maternal folic acid use, and risk of childhood acute lymphoblastic leukemia

Association of the DNA Methyltransferase and Folate Cycle Enzymes’ Gene Polymorphisms with Coronary Restenosis

Background: In recent years, the interest in genetic predisposition studies for coronary artery disease and restenosis has increased. Studies show that polymorphisms of genes encoding folate cycle and homocysteine metabolism enzymes significantly contribute to atherogenesis and endothelial dysfunction. The purpose of this study was to examine some SNPs of genes coding for folate cycle enzymes and DNA methyltransferases as risk factors for in-stent restenosis. Methods: The study included 113 patients after stent implantation and 62 patients without signs of coronary artery disease at coronary angiography as the control group. Real-time PCR and RFLP-PCR were applied to genotype all participants for MTHFR rs1801133, MTHFR rs1801131, MTR rs1805087, MTRR rs1801394, DNMT1 rs8101626, DNMT3B rs1569686, and DNMT3B rs2424913 gene polymorphisms. Statistical data processing was carried out using the R language and the SPSS Statistics 20 software. Results: Statistically significant differences in the DNMT3B gene polymorphisms were found between patients with and without in-stent restenosis. An association of TT rs1569686 and TT rs2424913 genotypes with the development of restenosis was revealed. The TT rs1569686 genotype was more frequent in the patients under the age of 65 years and in the subgroup of patients with post-12-month restenosis, as was the minor GG genotype for MTR rs1805087. The homozygous TT genotype for MTHFR rs1801133 was significantly more frequent in the subgroup over 65 years old. The frequencies of the heterozygous genotype for the MTRR gene and the minor GG homozygotes for the DNMT1 gene were significantly higher in the subgroup with in-stent restenosis under 65 years old. Conclusions: The results of this study could be used for a comprehensive risk assessment of ISR development, determining the optimal tactics and an individual approach in the treatment of patients with coronary artery disease before or after percutaneous coronary interventions, including homocysteine-lowering treatment in patients with hyperhomocysteinemia and a high risk of in-stent restenosis.

Association of MTHFR 677C > T, 1298A > C and MTR 2756A > G Polymorphisms with Susceptibility to Childhood Retinoblastoma: A Systematic Review and Met-Analysis

BackgroundRecently, epidemiological studies investigating the association of MTHFR 677 C > T, 1298 A > C and MTR 2756 A > G polymorphism with retinoblastoma susceptibility reported controversial results. Methods: Data were collected from several electronic databases such as PubMed, EMBASE, and Google Scholar databases, with the last search up to December 05, 2019. Results: A total of eleven case-control studies including four studies with 324 cases and 490 controls on MTHFR 677 C > T, four studies with 324 cases and 490 controls on MTHFR 1298 A > C, and three studies with 283 cases and 485 controls on MTR 2756 A > G were selected. There was a significant association between MTHFR 677 C > T and MTR 2756 A > G polymorphisms and an increased risk of retinoblastoma. However, MTHFR 1298 A > C polymorphism was not significantly associated with risk of retinoblastoma. Conclusion: This meta-analysis demonstrated that MTHFR 677 C > T and MTR 2756 A > G polymorphisms might play important roles in the development of retinoblastoma. No association with MTHFR 1298 A > C polymorphism was observed.

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 genes ARID5B, CEBPE and folate pathway with acute lymphoblastic leukemia in a population from the Brazilian Amazon region

Acute Lymphoblastic Leukemia (ALL) is the most common childhood neoplasia. Studies have shown that susceptibility to ALL may be modulated by genetic variables. Our study investigated 21 genetic variants in the susceptibility of the population of the Brazilian Amazon region to B-cell ALL. The variants of the genes GGH, CEBPE, ARID5B, MTHFR and MTHFD1 were related to a protective effect against the development of ALL, whereas the variant of the gene ATIC was associated with a risk effect. The results suggest that genetic variants analyzed modulate of the risk of developing ALL in the studied population.

Maternal Haplotypes in DHFR Promoter and MTHFR Gene in Tuning Childhood Acute Lymphoblastic Leukemia Onset-Latency: Genetic/Epigenetic Mother/Child Dyad Study (GEMCDS)

Childhood acute lymphoblastic leukemia (ALL) peaks around age 2–4, and in utero genetic epigenetic mother-fetus crosstalk might tune ALL onset during childhood life. Folate genes variably interact with vitamin status on ALL risk and prognosis. We investigated DHFR and MTHFR gene variants in 235 ALL children and their mothers to disclose their role in determining ALL onset age and survival. Pyrosequence of DHFR 19bp ins/del (rs70991108; W/D), MTHFR C677T (rs1801133; C>T), and MTHFR A1298C (rs1801131; A>C) was assessed in children and in 72% of mothers for dyad-analysis comparison. DHFR DD-children had delayed ALL onset compared to WW-children (7.5 ± 4.8 vs. 5.2 ± 3.7 years; P = 0.002) as well as MTHFR 1298 CC-children compared to AA-children (8.03 ± 4.8 vs. 5.78 ± 4.1 years; P = 0.006), and according to the strong linkage disequilibrium between MTHFR 677 T-allele and 1298C-allele, MTHFR TT-children showed early mean age of onset though not significant. Offspring of MTHFR 677 TT-mothers had earlier ALL onset compared to offspring of 677 CC-mothers (5.4 ± 3.3 vs. 7 ± 5.3 years; P = 0.017). DHFR/MTHFR 677 polymorphism combination influenced onset age by comparing DD/CC vs. WW/TT children (8.1 ± 5.7 vs. 4.7 ± 2.1 years; P = 0.017). Moreover, mother-child genotype combination gave 5.5-years delayed onset age in favor of DD-offspring of 677 CC-mothers vs. WW-offspring of 677 TT-mothers, and it was further confirmed including any D-carrier children and any 677 T-carrier mothers (P = 0.00052). Correction for multiple comparisons maintained statistical significance for DHFR ins/del and MTHFR A1298C polymorphisms. Unexpectedly, among the very-early onset group (<2.89 years; 25th), DD-genotype inversely clustered in children and mothers (4.8% vs. 23.8% respectively), and accordingly ALL offspring of homozygous DD-mothers had increased risk to have early-onset (adjusted OR (odds ratio) = 3.08; 1.1–8.6; P = 0.03). The opposite effect DHFR promoter variant has in tuning ALL onset-time depending on who is the carrier (i.e., mother or child) might suggest a parent-origin-effect of the D-allele or a two-faced epigenetic role driven by unbalanced folate isoform availability during the in-utero leukemogenesis responsible for the wide postnatal childhood ALL latency.

Methionine synthase A2756G polymorphism influences pediatric acute lymphoblastic leukemia risk: a meta-analysis

Plenty of studies have investigated the effect of methionine synthase (MTR) A2756G polymorphism on risk of developing pediatric acute lymphoblastic leukemia (ALL), but the available results were inconsistent. Therefore, a meta-analysis was conducted to derive a more precise estimation of the association between MTR A2756G polymorphism and genetic susceptibility to pediatric ALL. The PubMed, Embase, Google Scholar, Web of Science, ScienceDirect, Wanfang Databases and China National Knowledge Infrastructure were systematically searched to identify all the previous published studies exploring the relationship between MTR A2756G polymorphism and pediatric ALL risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were applied to evaluate the strength of association. Sensitivity analysis and publication bias were also systematically assessed. This meta-analysis finally included ten available studies with 3224 ALL cases and 4077 matched controls. The results showed that there was significant association between MTR A2756G polymorphism and risk of pediatric ALL in overall population (AG vs. AA: OR = 1.13, 95%CI = 1.02-1.26, P = 0.02; AG+GG vs. AA: OR = 1.13, 95%CI = 1.02-1.25, P = 0.01; G allele vs. A allele: OR = 1.10, 95%CI = 1.01-1.20, P = 0.03). In the stratification analyses by ethnicity, quality score and control source, significant association was found in Caucasians, population-based designed studies and studies assigned as high quality. In conclusion, this meta-analysis suggests that MTR A2756G polymorphism may influence the development risk of pediatric ALL in Caucasians. Future large scale and well-designed studies are required to validate our findings.

Maternal Red Blood Cell Folate and Infant Vitamin B12 Status Influence Methylation of Genes Associated with Childhood Acute Lymphoblastic Leukemia

SCOPE

Inadequate maternal folate intake is associated with increased childhood acute lymphoblastic leukemia (ALL) risk. Folate provides methyl groups for DNA methylation, which is dramatically disrupted in ALL. Whether or not maternal folate (and related B-vitamin) intake during pregnancy may affect ALL risk via influencing DNA methylation is investigated.

METHODS AND RESULTS

Genes in which methylation changes are reported both in response to folate status and in ALL are investigated. Folate-responsive genes (n = 526) are identified from mouse models of maternal folate depletion during pregnancy. Using published data, 2621 genes with persistently altered methylation in ALL are identified. Overall 25 overlapping genes are found, with the same directional methylation change in response to folate depletion and in ALL. Hypermethylation of a subset of genes (ASCL2, KCNA1, SH3GL3, SRD5A2) in ALL is confirmed by measuring 20 patient samples using pyrosequencing. In a nested cohort of cord blood samples (n = 148), SH3GL3 methylation is inversely related to maternal RBC folate concentrations (p = 0.008). Furthermore, ASCL2 methylation is inversely related to infant vitamin B12 levels. (p = 0.016).

CONCLUSION

Findings demonstrate proof of concept for a plausible mechanism, i.e., variation in DNA methylation, by which low intake of folate, and related B-vitamins during pregnancy may influence ALL risk.

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.

Childhood Leukemia and Primary Prevention

Leukemia is the most common pediatric cancer, affecting 3800 children per year in the United States. Its annual incidence has increased over the last decades, especially among Latinos. Although most children diagnosed with leukemia are now cured, many suffer long-term complications, and primary prevention efforts are urgently needed. The early onset of leukemia-usually before 5 years of age-and the presence at birth of "pre-leukemic" genetic signatures indicate that pre- and postnatal events are critical to the development of the disease. In contrast to most pediatric cancers, there is a growing body of literature-in the United States and internationally-that has implicated several environmental, infectious, and dietary risk factors in the etiology of childhood leukemia, mainly for acute lymphoblastic leukemia, the most common subtype. For example, exposures to pesticides, tobacco smoke, solvents, and traffic emissions have consistently demonstrated positive associations with the risk of developing childhood leukemia. In contrast, intake of vitamins and folate supplementation during the preconception period or pregnancy, breastfeeding, and exposure to routine childhood infections have been shown to reduce the risk of childhood leukemia. Some children may be especially vulnerable to these risk factors, as demonstrated by a disproportionate burden of childhood leukemia in the Latino population of California. The evidence supporting the associations between childhood leukemia and its risk factors-including pooled analyses from around the world and systematic reviews-is strong; however, the dissemination of this knowledge to clinicians has been limited. To protect children's health, it is prudent to initiate programs designed to alter exposure to well-established leukemia risk factors rather than to suspend judgment until no uncertainty remains. Primary prevention programs for childhood leukemia would also result in the significant co-benefits of reductions in other adverse health outcomes that are common in children, such as detriments to neurocognitive development.

Role of Electromagnetic Field Exposure in Childhood Acute Lymphoblastic Leukemia and No Impact of Urinary Alpha- Amylase--a Case Control Study in Tehran, Iran

Childhood acute lymphoblastic leukemia (ALL) is one of the most common hematologic malignancies which accounts for one fourth of all childhood cancer cases. Exposure to environmental factors around the time of conception or pregnancy can increase the risk of ALL in the offspring. This study aimed to evaluate the influence of prenatal and postnatal exposure to high voltage power lines on the incidence of childhood ALL. It also examines the role of various factors such as environmental factors and alpha-amylase as a marker in the development of leukemia. This cross-sectional case control study was carried out on 22 cases and 100 controls who born and lived in low socioeconomic families in Tehran and were hospitalized for therapeutic purposes in different hospitals of rom 2013-2014. With regard to the underlying risk factors; familial history and parental factors were detected as risk factors of ALL but in this age, socioeconomic and zonal matched case control study, prenatal and childhood exposure to high voltage power lines was considered as the most important environmental risk factor (p=0.006, OR=3.651, CI 95% 1.692-7.878). As the population study was from low socioeconomic state, use of mobiles, computers and microwaves was negligible. Moreover prenatal and postnatal exposure to all indoor electrically charged objects were not detected as significant environmental factors in the present study. This work defined the risk of environmental especially continuous pre and postnatal exposure to high voltage power lines and living in pollutant regions through the parents or children as well as the previously described risk factors of ALL for the first time in low socioeconomic status Iranian population.