Genetic Polymorphisms in the Folate Pathway and Risk of Childhood Acute Lymphoblastic Leukemia (ALL): MTHFR, MTHFD1, RFC1 and TS.

Introduction: Childhood ALL is the most common type of cancer in children. Although the survival rate is relatively high, there are significant clinical sequelae associated with treatment and little is known about the etiology of this condition. Family studies suggest a genetic component to ALL, and the peak incidence between 2 and 4 years of age indicates factors during pregnancy may influence risk. The folate metabolic pathway is a strong candidate for genetic epidemiologic studies due to its role in DNA synthesis and methylation. Objective: The purpose of this study was to conduct a case-parent triad analysis to assess both maternal and offspring genetic effects of the folate metabolic pathway on childhood ALL risk. Methods: We recruited pediatric ALL case-parent triads (n = 120) from Texas Children's Hospital. DNA samples were genotyped in the Human Genetics Center at The University of Texas School of Public Health using the Sequenom iPLEX MassARRAY for 80 tagSNPs in six folate metabolic pathway genes (MTHFR, MTRR, MTR, DHFR, BHMT, and TYMS). Log-linear modeling was used to examine the associations between ALL and both maternal and offspring genotypes. Results: After controlling for the false discovery rate (<0.10), there were 19 significant maternal effects in the following genes: BHMT (n = 3), MTR (n = 12), and TYMS (n = 4). For instance, maternal genotypes for BHMT rs558133 (RR = 0.51, 95% CI: 0.30-0.88, p = 0.008, q = 0.08), MTR rs2282369 (RR = 0.46, 95% CI: 0.26-0.79, p = 0.003, q = 0.08), and TYMS rs699517 (RR = 1.92, 95% CI: 1.17-3.17, p = 0.006, q = 0.08) were all associated with ALL. There were no significant offspring effects after controlling for the false discovery rate. Conclusions: This is one of the few studies conducted to evaluate maternal genetic effects in the context of pediatric ALL risk. Furthermore, we employed a family-based design (i.e., case-parent triad) that is robust to confounding due to population structure and allows for the evaluation of both maternal and offspring genotypes. These results provide additional evidence that the risk of pediatric ALL is influenced by variation within folate pathway genes and indicate that studies to explore these relationships further are warranted. We plan to extend these analyses to the evaluate folate pathway haplotypes, as well as other relevant genetic pathways (e.g., DNA repair). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2649. doi:1538-7445.AM2012-2649

Background:Prenatal folate supplementation has been consistently associated with a reduced risk of childhood acute lymphoblastic leukemia (ALL). Previous germline genetic studies examining the one carbon (folate) metabolism pathway were limited in sample size, scope, and population diversity and led to inconclusive results.Methods:We evaluated whether ∼2,900 single-nucleotide polymorphisms (SNP) within 46 candidate genes involved in the folate metabolism pathway influence the risk of childhood ALL, using genome-wide data from nine case-control studies in the Childhood Cancer and Leukemia International Consortium (n = 9,058 cases including 4,510 children of European ancestry, 3,018 Latinx, and 1,406 Asians, and 92,364 controls). Each study followed a standardized protocol for quality control and imputation of genome-wide data and summary statistics were meta-analyzed for all children combined and by major ancestry group using METAL software.Results:None of the selected SNPs reached statistical significance, overall and for major ancestry groups (using adjusted Bonferroni P-value of 5 × 10−6 and less-stringent P-value of 3.5 × 10−5 accounting for the number of “independent” SNPs). None of the 10 top (nonsignificant) SNPs and corresponding genes overlapped across ancestry groups.Conclusions:This large meta-analysis of original data does not reveal associations between many common genetic variants in the folate metabolism pathway and childhood ALL in various ancestry groups.Impact:Genetic variants in the folate pathway alone do not appear to substantially influence childhood acute lymphoblastic leukemia risk. Other mechanisms such as gene–folate interaction, DNA methylation, or maternal genetic effects may explain the observed associations with self-reported prenatal folate intake.

Microsomal epoxide hydrolase, EPHX1, plays a central role in the detoxification of potentially genotoxic epoxide intermediates. In this study, we firstly aimed to investigate the relationship between EPHX1 Tyr113His and His139Arg variants, and the risk of incidence of childhood acute lymphoblastic leukemia (ALL) in Turkish population, comprised of 190 healthy controls and 167 ALL patients. In exon 3 Tyr113His polymorphism, 113His/His homozygous mutant genotype with slow activity was 18.6% in ALL patients and 9% in controls, indicating 113His/His slow activity genotype was significantly associated with an increased risk of childhood ALL (OR: 2.3, 95% CI, 1.2-4.4, P = 0.01). No significant association was found between exon 4 His139Arg variant and the risk of ALL. When both exon 3 Tyr113His and exon 4 His139Arg polymorphisms were considered together, only the exon 3 113His/His, homozygous mutant, slow activity genotype with exon 4 wild-type genotype 139His/His was significantly increased the risk of ALL 2.4-fold (OR: 2.4, P = 0.02). We also evaluated whether haplotype analysis for EPHX1 Tyr113His polymorphism together with DNA protein XRCC1 Arg399Gln variant known for its deficient DNA repair capacity would represent more prominent risk factors for the development of childhood ALL. Accordingly, the co-presence of Tyr113His variant of EPHX1 and Arg399Gln variant of XRCC1 in the same individuals significantly increased the risk of childhood ALL up to 2.1-fold (OR = 2.1, P = 0.03). Moreover, homozygous mutant genotype for both genes significantly and considerably increased the risk of childhood ALL 8.5-fold (OR: 8.5, P = 0.03). In conclusion, individuals with EPHX1 113His/His slow activity genotype may not detoxify reactive carcinogenic epoxides efficiently, binding of reactive epoxides to DNA cause DNA damage. With the inadequate polymorphic DNA repair protein, XRCC1, this situation ultimately leads to significantly increased susceptibility for childhood ALL.

Surrogate measures of infectious exposures have been consistently associated with lower childhood acute lymphoblastic leukemia (ALL) risk. However, recent reports have suggested that physician-diagnosed early-life infections increase ALL risk, thereby raising the possibility that stronger responses to infections might promote risk. We examined whether medically diagnosed infections were related to childhood ALL risk in an integrated health-care system in the United States. Cases of ALL (n=435) diagnosed between 1994-2014 among children aged 0-14 years, along with matched controls (n=2,170), were identified at Kaiser Permanente Northern California. Conditional logistic regression was used to estimate risk of ALL associated with history of infections during first year of life and across the lifetime (up to diagnosis). History of infection during first year of life was not associated with ALL risk (odds ratio (OR)=0.85, 95% confidence interval (CI): 0.60, 1.21). However, infections with at least 1 medication prescribed (i.e., more "severe" infections) were inversely associated with risk (OR=0.42, 95% CI: 0.20, 0.88). Similar associations were observed when the exposure window was expanded to include medication-prescribed infections throughout the subjects' lifetime (OR=0.52, 95% CI: 0.32, 0.85).

Objective:Tobacco smoke contains carcinogens known to damage somatic and germ cells. In this study, we investigated the effect of tobacco smoking on the risk of childhood acute lymphoblastic leukemia (ALL) and myeloid leukemia (AML).Methods:Information about tobacco smoking exposures of the mother before, during, and after pregnancy was collected via PubMed, Embase, and Web of Science databases through November 5, 2018. We performed to evaluate the association between smoking exposure and the risk of childhood ALL and AML. Study selection, data abstraction, and quality assessment were performed by 2 independent reviewers. Random effects models were used to obtain summary odds ratios (ORs) and 95% confidence intervals (CIs).Results:Nineteen case–control studies of childhood leukemia (age < 15 years) conducted in 9 countries from 1974 to 2018. Maternal smoking exposures did not a significant association with childhood ALL (OR = 1.004, 95% CI 0.953–1.058, P = .881) and AML (OR = 0.92, 95% CI 0.815–1.038, P = .177) during exposure time windows. However, there was an association with paternal smoking and ALL (OR = 1.15, 95% CI 1.038–1.275, P = .007). Paternal smoking in AML showed there was no association with smoking exposures and childhood AML (OR = 1.133, 95% CI 0.943–1.362, P = .181). Next, maternal daily cigarettes consumption showed no associations with ALL (OR = 1.08, 95% CI 1.000–1.168, P = .051) during pregnancy. No association with maternal daily smoking and AML (OR = 0.909, 95% CI 0.682–1.211, P = .514). Paternal daily cigarettes consumption was associated with increased risks of childhood ALL (OR = 1.200, 95% CI 1.112–1.302, P = .000). The higher consumption of paternal smoking (more than 10 per day) was significantly related to childhood ALL. Paternal daily smoking consumption also was related to AML (OR = 1.242, 95% CI 1.031–1.496, P = .022).Conclusion:Maternal smoking before, during, or after pregnancy was not associated with childhood ALL or AML. However, paternal smoking was related to a significantly elevated risk of childhood ALL during pregnancy, but not for AML. Maternal daily smoking consumption was not associated with ALL or AML during pregnancy. The higher consumption of paternal smoking were, the higher the risk of childhood ALL or AML.

BackgroundRecently, there have been a number of studies on the association between XRCC1 polymorphisms and childhood acute lymphoblastic leukemia (ALL) risk. However, the results of previous reports are inconsistent. Thus, we performed a meta-analysis to clarify the effects of XRCC1 variants on childhood ALL risk.MethodsA meta-analysis was performed to examine the association between XRCC1 polymorphisms (Arg399Gln, Arg194Trp, and Arg280His) and childhood ALL risk. We critically reviewed 7 studies with a total of 880 cases and 1311 controls for Arg399Gln polymorphism, 3 studies with a total of 345 cases and 554 controls for Arg280His polymorphism, and 6 studies with a total of 783 cases and 1180 controls for Arg194Trp polymorphism, respectively. Odds ratio (OR) and its 95% confidence interval (CI) were used.ResultsSignificant association between XRCC1 Arg399Gln polymorphism and childhood ALL risk was observed in total population analyses (ORadditive model = 1.501, 95% CI 1.112–2.026, POR = 0.008; ORdominant model = 1.316, 95% CI = 1.104–1.569, POR = 0.002) and Asian subgroup analyses (ORadditive model = 2.338, 95%CI = 1.254–4.359, POR = 0.008; ORdominant model = 2.108, 95%CI = 1.498–2.967, POR = 0.000). No association was detected in Caucasians, Metizo and mixed populations. Ethnicity was considered as a significant source of heterogeneity in the meta-regression model. For the other two XRCC1 polymorphisms, no association with childhood ALL risk was found.ConclusionsThe meta-analysis results suggested that XRCC1 Arg399Gln polymorphism might be associated with elevated childhood ALL risk among Asian population.

Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms have been implicated in childhood acute lymphoblastic leukemia (ALL) risk, but previously published studies were inconsistent and recent meta-analyses were not adequate. In a meta-analysis of 21 publications with 4,706 cases and 7,414 controls, we used more stringent inclusion method and summarized data on associations between MTHFR C677T and A1298C polymorphisms and childhood ALL risk. We found an overall association between 677T variant genotypes and reduced childhood ALL risk. Specifically, in the dominant genetic model, an association was found in a fixed-effect (TT + CT vs. CC: OR = 0.92; 95% CI = 0.85-0.99) but not random-effect model, whereas such an association was observed in both homozygote genetic model (TT vs. CC: OR = 0.80; 95% CI = 0.70-0.93 by fixed effects and OR = 0.78; 95% CI = 0.65-0.93 by random effects) and recessive genetic model (TT vs. CC + CT: OR = 0.83; 95% CI = 0.72-0.95 by fixed effects and OR = 0.84; 95% CI = 0.73-0.97 by random effects). These associations were also observed in subgroups by ethnicity: for Asians in all models except for the dominant genetic model by random effect and for Caucasians in all models except for the recessive genetic model. However, the A1298C polymorphism did not appear to have an effect on childhood ALL risk. These results suggest that the MTHFR C677T, but not A1298C, polymorphism is a potential biomarker for childhood ALL risk.

Xenobiotic and folate metabolic pathways are important for the maintenance of genetic stability and may influence susceptibility to the development of childhood acute lymphoblastic leukaemia (ALL). In this study, we investigated 10 polymorphisms in 6 genes (GSTM1-present/null, GSTT1-present/null, GSTP1 1578A > G, NQO1 609C > T, MTHFR 677C > T, MTHFR 1298A > C, MTHFD1 1958G > A, 3'-TYMS 1494 6bp-deletion/insertion, 5'-TYMS 28bp-tandem repeats, and SLC19A1 80G > A) in a cohort of 185 Javanese children with ALL and 177 healthy controls. In ALL patients, none of the polymorphisms demonstrated a statistically significant association with ALL after correcting for multiple comparisons. Gender-stratified analysis showed that in girls, GSTT1-null genotype was associated with increased ALL risk (OR = 2.20; p = 0.027), while GSTP1 1578AG genotype was associated with reduced risk (OR = 0.43; p = 0.031). Strong linkage disequilibrium between the MTHFR 677C > T and 1298A > C polymorphisms was observed (D' = 1.0; r(2) = 0.072). The haplotypes 677C-1298C and 677T-1298A were associated with a reduced risk of ALL (OR = 0.68 and 0.64, respectively; gender-adjusted global p = 0.028). Classification and regression tree (CART) analysis was employed to identify potential high-order gene-gene interactions and cluster subjects into susceptibility groups. SLC19A1 80G > A emerged as the predominant polymorphism associated with risk of ALL. Individuals simultaneously carrying MTHFR 1298AA, 3'-TYMS 6bp deletion(s) and SLC19A1 80A-allele(s) were at higher disease risk (OR = 2.21; p < 0.001). On the contrary, simultaneous possession of MTHFR 1298CC, 3'-TYMS 6bp homozygosity and SLC19A1 80A-allele(s) conferred lower risk (OR = 0.25; p = 0.004). Carriage of NQO1 609C-allele amongst SLC19A1 80GG genotype was associated with lower risk (OR = 0.47; p = 0.003). In conclusion, our study has demonstrated the importance of gender and gene-gene interaction within the xenobiotic and folate pathways in modulating childhood ALL susceptibility.

Methylenetetrahydrofolate Reductase (MTHFR) C677T Polymorphism Decreases Risk of Childhood Acute Lymphoblastic Leukemia (ALL): A Study of the Chinese and Malay Population.

DNA repair gene XPD and XRCC1 polymorphisms and the risk of childhood acute lymphoblastic leukemia

It has been proposed that infections in infancy and early childhood are associated with a reduced risk of childhood acute lymphoblastic leukaemia (ALL). We tested this hypothesis in a register-based study of hospitalisations for infectious diseases prior to diagnosis of childhood ALL. A nation-wide cohort encompassing all Danish children aged 0-14 years and born between 1977 and 2008 (N = 1,778,129) was established and followed for hospitalisations for infectious diseases and risk of childhood ALL. The exposure was lagged 1 year to limit reverse causality. In the statistical analyses exposure was defined as (time dependent) number of early or late (before 2 or at/after 2 years of age) hospitalisations to further explore possible age-dependent associations. A total of 815 children were diagnosed with ALL during follow-up. Risk of ALL was associated neither with hospitalisations for infectious diseases before (incidence rate ratio = 0.92, 95% confidence interval 0.78-1.07) nor at/after 2 years of age (incidence rate ratio = 1.04, 95% confidence interval 0.81-1.32). This also applied to subsets of ALL supposedly initiated prenatally. The absence of association between hospitalisation for infections and risk of childhood ALL directs future investigations of the role of infections in development of childhood ALL towards exploration of less severe infections.

Association of three polymorphisms in ARID5B, IKZF1and CEBPE with the risk of childhood acute lymphoblastic leukemia in a Chinese population

Genetic polymorphisms in the promoter regions of FAS, FASL and CASP8 involved in the apoptotic signaling pathway are thought to be associated with susceptibility to cancer. We hypothesized that these functional genetic variants might be associated with the risk of childhood acute lymphoblastic leukemia (ALL). A case–control study in a Chinese population with 361 cases of ALL and 519 controls was performed to evaluate the association between FAS, FASL and CASP8 variants and risk of childhood ALL. Individuals with FAS − 1377AG had an odds ratio (OR) of 0.72 for the risk of ALL compared to − 1377GG and the variant FASL − 844CC was associated with a statistically significantly decreased risk of childhood ALL (OR = 0.38). Furthermore, combined genotypes with 5–8 protective alleles were associated with a significantly decreased risk of childhood ALL compared with those with 0–4 variants, and this decreased risk was more pronounced among the subgroups of age < 6 years, female, parental never-drinking status and never house-painting. Our results provide evidence that FAS–FASL–CASP8 polymorphisms contributed to a reduced risk of childhood ALL in our population. Larger studies are warranted to validate our findings.

We conducted a case-parent triad study evaluating the role of maternal and offspring genotypes in the folate metabolic pathway on childhood acute lymphoblastic leukemia (ALL) risk. Childhood ALL case-parent triads (n = 120) were recruited from Texas Children's Hospital. DNA samples were genotyped using the Sequenom iPLEX MassARRAY for 68 tagSNPs in six folate metabolic pathway genes (MTHFR, MTRR, MTR, DHFR, BHMT, and TYMS). Log-linear modeling was used to examine the associations between maternal and offspring genotypes and ALL. After controlling for the false discovery rate (<0.1), there were 20 significant maternal effects in the following genes: BHMT (n = 3), MTR (n = 12), and TYMS (n = 5). For instance, maternal genotypes for BHMT rs558133 (relative risk [RR] = 0.51, 95 % confidence interval [CI]: 0.30-0.87, p = 0.008, Q = 0.08) and MTR rs2282369 (RR = 0.46, 95 % CI: 0.27-0.80, p = 0.004, Q = 0.08) were associated with ALL. There were no significant offspring effects after controlling for the false discovery rate. This is one of the few studies conducted to evaluate maternal genetic effects in the context of childhood ALL risk. Furthermore, we employed a family-based design that is less susceptible to population stratification bias in the estimation of maternal genetic effects. Our findings suggest that maternal genetic variation in the folate metabolic pathway is relevant in the etiology of childhood ALL. The observed maternal genetic effects support the need for continued research of how the uterine environment may influence risk of ALL.

Pri-miR-34b/c rs4938723 polymorphism is associated with the risk of childhood acute lymphoblastic leukemia