Polymorphisms in theMTHFRgene and their possible association with susceptibility to childhood acute lymphocytic leukemia in an Indian population

Lack of Impact of the A1298C MTHFR on the Risk of Childhood Acute Lymphoblastic Leukemia: Evidence from a Meta-analysis

To clarify the effect of the A1298C variant of methylenetetrahydrofolate reductase (MTHFR) gene on the risk of acute lymphoblastic leukemia (ALL), an updated meta-analysis was performed. Electronic literature search was carried out in PubMed to collect relevant articles. Pooled odds ratios (OR) and stratification analysis were achieved under different genetic comparison models, age and ethnicity. A total of 46 articles including 7020 cases and 12,114 controls were enrolled. Overall, no significant association was observed for the MTHFR A1298C variant on the risk of ALL in any genetic model test, when all the studies pooled together (OR ~ 1 0.91; p > 0.05). In subgroup analyses stratified by age and ethnicity, the MTHFR A1298C reduce the risk of ALL in adult under allele contrast (OR = 0.88; [0.72; 1.09], p = 0.23) mainly in Caucasian populations. The present meta-analysis provides evidence that the A1298C variant of MTHFR gene is unlikely to be a major risk gene for childhood ALL.

Assessment of the relationship between methylenetetrahydrofolate reductase polymorphism and acute lymphoblastic leukemia: Evidence from an updated meta-analysis

OBJECTIVE

The methylenetetrahydrofolate reductase gene C677T polymorphism is closely related to the acute lymphoblastic leukemia. Several case-control studies have investigated this association; however, no conclusions could be drawn. A comprehensive updated meta-analysis is established to explain these contradictions and clarify the overall impact of this variant on the susceptibility to acute lymphoblastic leukemia.

METHODS

Electronic searches were conducted to select published studies prior to June 2018. Pooled odds ratios and stratification analysis were performed under different genetic comparison models, age, and ethnicity.

RESULTS

Totally, 66 case-control studies including 9619 acute lymphoblastic leukemia cases and 17,396 controls were selected. Our analyses showed that methylenetetrahydrofolate reductase C677T polymorphism was protective mainly in Asian and European countries, under all genetic models and regardless of age, but leukemogenic in mixed population.

CONCLUSION

Thus, C677T polymorphism may be a promising acute lymphoblastic leukemia biomarker, but they should be interpreted with caution considering other factors such as folic acid intake, gene-gene and gene-environment interactions.

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 of methylenetetrahydrofolate reductase genotypes with the risk of childhood leukemia in Taiwan

Background

Acute lymphoblastic leukemia (ALL) is the most prevalent type of pediatric cancer, the causes of which are likely to involve an interaction between genetic and environmental factors. To evaluate the effects of the genotypic polymorphisms in methylenetetrahydrofolate reductase (MTHFR) on childhood ALL risk in Taiwan, two well-known polymorphic genotypes of MTHFR, C677T (rs1801133) and A1298C (rs1801131), were analyzed to examine the extent of their associations with childhood ALL susceptibility and to discuss the MTHFR genotypic contribution to childhood ALL risk among different populations.

Methodology/Principal Findings

In total, 266 patients with childhood ALL and an equal number of non-cancer controls recruited were genotyped utilizing PCR-RFLP methodology. The MTHFR C677T genotype, but not the A1298C, was differently distributed between childhood ALL and control groups. The CT and TT of MTHFR C677T genotypes were significantly more frequently found in controls than in childhood ALL patients (odds ratios=0.60 and 0.48, 95% confidence intervals=0.42–0.87 and 0.24–0.97, respectively). As for gender, the boys carrying the MTHFR C677T CT or TT genotype conferred a lower odds ratio of 0.51 (95% confidence interval=0.32–0.81, P=0.0113) for childhood ALL. As for age, those equal to or greater than 3.5 years of age at onset of disease carrying the MTHFR C677T CT or TT genotype were of lower risk (odds ratio= 0.43 and 95% confidence interval=0.26–0.71, P=0.0016).

Conclusions

Our results indicated that the MTHFR C677T T allele was a protective biomarker for childhood ALL in Taiwan, and the association was more significant in male patients and in patients 3.5 years of age or older at onset of disease.

Association between MTHFR C677T polymorphism and risk of acute lymphoblastic leukemia: a meta-analysis based on 51 case-control studies

Background

Studies and systematic reviews have reached inconsistent conclusions on the role of 5, 10-methylenetetrahydrofolate reductase (MTHFR) polymorphism C677T in acute lymphoblastic leukemia (ALL) risk.

Material/Methods

The present meta-analysis comprising of 51 case-control studies, including 7892 cases and 14 280 controls was performed to reevaluate the association between MTHFR C677T polymorphism and ALL risk.

Results

Statistical differences were found in the dominant model (TT+CT vs. CC, odd ratio (OR)=0.89, 95% CI, 0.79–1.00, P=0.04) and the CT vs. CC (OR=0.89, 95% CI, 0.80–1.00, P=0.05), but not in the allele contrast model (T vs. C, OR=0.92, 95% CI, 0.84–1.01, P=0.08), additive model (TT vs. CC, OR=0.87, 95% CI, 0.73–1.05, P=0.15), or recessive model (TT vs. CT+CC, OR=0.94, 95% CI, 0.81–1.10, P=0.44) in overall populations. In the subgroup analyses stratified by age (children and adults) and ethnicity (Asian and Caucasian), no significant associations between MTHFR C677T polymorphism and ALL risk were observed.

Conclusions

The current study found no sufficient evidence of a protective role of MTHFR C677T polymorphism in ALL susceptibility.

MTHFR gene polymorphism in acute lymphoblastic leukemia among North Indian children: a case-control study and meta-analysis updated from 2011

Studies on the association of methylenetetrahydrofolate reductase (MTHFR) genotype in childhood acute lymphoblastic leukemia (ALL) have yielded conflicting results. The present study examines this association in north Indian children with ALL and includes an updated meta-analysis. MTHFR (677 and 1298) genotype of children with ALL and healthy adult controls were done by the PCR-restriction fragment length polymorphism (PCR-RFLP) method and were compared using various models of inheritance. A total of 150 patients and 300 controls were included. The 677T allele was found protective (odds ratio (OR) 0.21, 95% confidence interval (CI) 0.04-0.94), whereas 1298C allele led to an increase in risk (OR 4.44, 95% CI 2.19-8.99) of childhood ALL. Meta-analysis included 31 and 27 studies examining the association of 677 and 1298 genotypes, respectively. The 677 C -> T polymorphism was protective (OR 0.90, 95% CI 0.82-0.99). Protection was more pronounced in folate-sufficient populations as compared with those not covered by folate fortification guidelines. The 1298A->C polymorphism was associated with a marginal increase in risk (OR 1.19, 95% CI 1.01-1.40).

Association of methylenetetrahytrofolate reductase (MTHFR) C677T and A1298C polymorphisms with the susceptibility of childhood acute lymphoblastic leukaemia (ALL) in Chinese population

Background

The aim of this study was to investigate the relationship between the polymorphisms of the methylenetetrahytrofolate reductase (MTHFR) gene and susceptibility to childhood acute lymphoblastic leukemia (ALL).

Methods

A case–control study was conducted among 98 children with ALL and 93 age- and sex- matched non-ALL controls. Genotyping of MTHFR C677T and A1298C polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The odds ratios (ORs) of MTHFR genotypes were used to assess the associations of these polymorphisms with childhood ALL susceptibility.

Results

No significant differences were observed for frequencies of the 677CC, 677CT and 677TT genotypes between patients and controls. Frequencies of the 1298AA, 1298 AC and 1298CC genotypes between the two groups were significantly different. The risk of ALL with the 1298C allele carriers (AC + CC) was elevated by 1.1 times compared with the AA genotype [OR = 2.100; 95% CI (1.149; 3.837); P = 0.015].

Conclusions

The MTHFR A1298C polymorphism is associated with susceptibility to childhood ALL in the Chinese population.

MTHFR Gene Polymorphisms and the Risk of Acute Lymphoblastic Leukemia in Adults and Children: A Case Control Study in India

Genetic polymorphisms in the methylene tetrahydrofolate reductase (MTHFR) gene have been associated with the development of acute leukemias and various malignancies. The role of MTHFR polymorphism in the development of pediatric acute lymphoblastic leukemia (ALL) has been extensively studied among north Indians in various settings, yet its association with acute leukemias remains unresolved. To evaluate the relationship between functional MTHFR polymorphisms, C677T and A1298C and possible effect on risk of ALL in adults and children in North Indian population by comparing them with healthy controls. DNA was isolated from peripheral blood of 184 ALL patients (33 adults, 151 children) and 155 controls and analyzed by a PCR-restriction fragment length polymorphism assay. The frequency of MTHFR 677CT and 1298 AC genotypes were significantly lower among adult ALL cases when compared to the controls. We found a 1.74-fold reduced risk of ALL in individuals with 1298AC polymorphic variant and a 9.17-fold decreased risk of adult ALL. However, no statistically significant difference was evident between the above polymorphisms and susceptibility to ALL in children. Polymorphisms in the MTHFR gene possibly modulate risk of ALL in north Indian adults but not in children, although larger studies are needed.

A literature review of MTHFR (C677T and A1298C polymorphisms) and cancer risk

5,10-Methlenetetrahydrofolate reductase (MTHFR) is one of the most important enzymes for folate metabolism. This enzyme is mapped on chromosome 1, which is located at the end of the short arm (1p36.3). The C677T and A1298C are MTHFR polymorphisms that decrease in vitro MTHFR enzyme activity. Folate metabolism plays a key role in cell metabolism. These reactions are associated with purine-pyrimidine synthesis: DNA, RNA, and protein methylation. Polymorphism is also a factor in biodiversity, and be affected by ethnic heritage and geographic locale. In the case of unknown outcomes, not only should all geographical regions be investigated to ascertain biodiversity, but all populations as well to fully understand the variations in the effect. PUBMED was searched from January 2006 to December 2011 to develop an investigatory pursuit strategy. MTHFR, cancer, C677T, A1298C, and polymorphisms were key words used to focus the search. The literature review included all published relevant cancer types and MTHFR polymorphisms for that 5 years period. All selected polymorphisms data for cancer types was listed in tables for easy access and retrieval.

Methylenetetrahydrofolate reductase gene polymorphisms as predictive and prognostic biomarkers in ovarian cancer risk

Early diagnosis and better prognosis of ovarian cancer is still a challenge. Besides environmental risk factors, genetic factors have established a role in pathogenesis of ovarian cancer.

METHODS

A case-control and a prospective study design conducted in 224 ovarian cancer patients and 432 controls in Chinese population. MTHFR C677T genotyping was done by PCR-RFLP.

RESULTS

Patients with ovarian cancer is associated with a higher less number of delivery and less frequent oral contraceptive use. When potential confounding factors adjusted logistic regression analysis between cases and controls were performed, significant association was obtained for 677T/T genotype and ovarian cancer (OR=3.13, 95% CI=1.59-5.72). Cox regression survival analysis showed individuals carrying T/T genotype had significantly increased HR for death in ovarian cancer patients (HR=2.86, 95% CI=1.27-7.93). In conclusion, we observed that the MTHFR C677T polymorphism is associated with the susceptibility and survival of ovarian cancer in Chinese population.

Methylenetetrahydrofolate reductase polymorphisms and risk of acute lymphoblastic leukemia-evidence from an updated meta-analysis including 35 studies

Background

5,10-methylenetetrahydrofolate reductase (MTHFR) variants, C677T and A1298C, have been reported to be associated with decreased risk of acute lymphoblastic leukemia (ALL). However, results derived from individually underpowered studies are conflicting. We carried out an updated meta-analysis on the association between MTHFR polymorphisms and ALL risk.

Methods

Relevant publications were searched through PUBMED and EMBASE databases. The associations between MTHFR C677T and A1298C polymorphisms and the risk of ALL were evaluated by odds ratios (ORs). The heterogeneity and publication bias were estimated. Meta-regression analysis was performed to evaluate the potential sources of heterogeneity.

Results

C677T polymorphism was associated with a reduced risk of ALL (allele contrast: OR_RE = 0.91, 95% CI: 0.83-0.99). Subgroup analysis showed MTHFR C677T variant was associated with decreased susceptibility to ALL in children and Caucasians. Meta-regression showed the logOR for the association between T allele and ALL increased as sex ratio (M/F) in the case group increased (P = 0.01). Regarding A1298C polymorphism, no significant association was observed (allele contrast: OR_RE = 1.01, 95% CI: 0.91-1.11). There was no publication bias for C677T or A1298C polymorphism.

Conclusions

The present meta-analysis suggests that the C677T polymorphism, not A1298C, in MTHFR gene is associated with a decreased risk of ALL, particularly among children and Caucasians subjects. Our findings suggest that the influence of the C677T polymorphism on ALL susceptibility is modified by sex ratio in cases (M/F). Since folate intake may be a possible confounding factor, including this factor in future prospective studies is warranted. Further meta-analysis studies should be at least stratified for folate levels and gender to give more powerful and informative results.

Folic acid supplementation, MTHFR and MTRR polymorphisms, and the risk of childhood leukemia: the ESCALE study (SFCE)

PURPOSE

Fetal folate deficiency may increase the risk of subsequent childhood acute leukemia (AL), since folates are required for DNA methylation, synthesis, and repair, but the literature remains scarce. This study tested the hypothesis that maternal folic acid supplementation before or during pregnancy reduces AL risk, accounting for the SNPs rs1801133 (C677T) and rs1801131 (A1298C) in MTHFR and rs1801394 (A66G) and rs1532268 (C524T) in MTRR, assumed to modify folate metabolism.

METHODS

The nationwide registry-based case-control study, ESCALE, carried out in 2003-2004, included 764 AL cases and 1,681 controls frequency matched with the cases on age and gender. Information on folic acid supplementation was obtained by standardized telephone interview. The genotypes were obtained using high-throughput platforms and imputation for untyped polymorphisms. Odds ratios (OR) were estimated using unconditional regression models adjusted for potential confounders.

RESULTS

AL was significantly inversely associated with maternal folic acid supplementation before and during pregnancy (OR = 0.4; 95 % confidence interval: [0.3-0.6]). MTHFR and MTRR genetic polymorphisms were not associated with AL. However, AL was positively associated with homozygosity for any of the MTHFR polymorphisms and carriership of both MTRR variant alleles (OR = 1.6 [0.9-3.1]). No interaction was observed between MTHFR, MTRR, and maternal folate supplementation.

CONCLUSION

The study findings support the hypothesis that maternal folic acid supplementation may reduce the risk of childhood AL. The findings also suggest that the genotype homozygous for any of the MTHFR variants and carrying both MTRR variants could be a risk factor for AL.

A meta-analysis of MTHFR C677T and A1298C polymorphisms and risk of acute lymphoblastic leukemia in children

BACKGROUND

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.

PROCEDURES

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.

RESULTS

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.

CONCLUSIONS

These results suggest that the MTHFR C677T, but not A1298C, polymorphism is a potential biomarker for childhood ALL risk.

Variants of the MTHFR gene and susceptibility to acute lymphoblastic leukemia in children: a synthesis of genetic association studies

BACKGROUND

Acute lymphoblastic leukemia (ALL) is a complex disease with genetic background. The genetic association studies (GAS) that investigated the association between ALL and the MTHFR C677T and A1298C gene variants have produced contradictory or inconclusive results.

MATERIALS AND METHODS

In order to decrease the uncertainty of estimated genetic risk effects, a meticulous meta-analysis of published GAS related the variants in the MTFHR gene with susceptibility to ALL was conducted. The risk effects were estimated based on the odds ratio (OR) of the allele contrast and the generalized odds ratio (OR(G)). Cumulative and recursive cumulative meta-analyses were also performed.

RESULTS

The analysis showed marginal significant association for the C677T variant, overall [OR=0.91 (0.82-1.00) and OR(G)=0.89 (0.79-1.01)], and in Whites [OR=0.88 (0.77-0.99) and OR(G)=0.85 (0.73-0.99)]. The A1298C variant produced non-significant results. For both variants, the cumulative meta-analysis did not show a trend of association as evidence accumulates and the recursive cumulative meta-analysis indicated lack of sufficient evidence for denying or claiming an association.

CONCLUSION

The current evidence is not sufficient to draw definite conclusions regarding the association of MTHFR variants and development of ALL.

Cyclooxygenase-2-765G>C functional promoter polymorphism and its association with oral squamous cell carcinoma

AIM

Cyclooxygenase-2 is a key enzyme in the conversion of arachidonic acid to prostaglandins, and has critical role in the progression of several malignancies, including oral squamous cell carcinoma.

METHODS

We designed a case-control study to evaluate the susceptibility of the functional -765G>C genetic variation in oral squamous cell carcinoma patients. Polymerase chain reaction-based restriction fragment length polymorphism analysis was used to determine the polymorphism in oral squamous cell carcinoma (n = 150) patients and healthy controls (n = 150).

RESULTS

The genotype frequencies of cyclooxygenase-2 765G>G, 765G>C, and 765C>C were 73.3%, 18.66%, and 8.0% in the cancer patients, and 94.66%, 4% and 1.3% in the controls, respectively. The cyclooxygenase-2 GC and CC genotypes were significantly associated (P = 0.0003 and P = 0.01, respectively) with oral squamous cell carcinoma patients, when compared to the controls. The 765G>C genotypes were statistically significant, with habitual tobacco chewing and alcohol consumption + smoking (P = 0.05).

CONCLUSIONS

This study highlights the genetic variant that might play a role in mediating susceptibility to oral squamous cell carcinoma in this population.

Evaluation of MTHFR677C>T polymorphism in prediction and prognosis of esophageal squamous cell carcinoma: a case-control study in a northern Indian population

Early diagnosis and better prognosis of esophageal squamous cell carcinoma (ESCC) is still a challenge. Besides environmental risk factors, nutritional deficiencies have an established role in pathogenesis of ESCC. Folate deficiency and functional polymorphisms in folate metabolizing genes such as methylene tetrahydrofolate reductase (MTHFR) 677C>T may have oncogenic role through disruption of normal DNA methylation pattern, synthesis, and impaired DNA repair. MTHFR677C>T or A222V (rs1801133) polymorphism has conflicting role in susceptibility to ESCC among different populations. Thus, we aimed to study the role of MTHFR677C>T polymorphism in susceptibility, survival, and interaction with environmental risk factors in ESCC patients from a northern Indian population. A case control study was performed in 208 ESCC incident cases (including 114 follow-up cases) and 223 healthy controls, and genotyping was done by PCR-RFLP. Our results show no significant association of MTHFR677C>T polymorphism with ESCC, tumor locations, or gender of subjects. However, we found a trend of decreased risk of ESCC due to interaction of MTHFR677CT genotype with smoking and alcohol intake. Kaplan Meier, and Cox regression survival analysis showed no prognostic impact of MTHFR677C>T polymorphism in ESCC patients. In conclusion, MTHFR677C>T polymorphism does not seem to have significant role either in susceptibility or survival of ESCC in a northern Indian population.

Candidate gene association studies and risk of childhood acute lymphoblastic leukemia: a systematic review and meta-analysis

To evaluate the contribution of candidate gene association studies to the understanding of genetic susceptibility to childhood acute lymphoblastic leukemia we conducted a systematic review and meta-analysis of published studies (January 1996-July 2009). Studies had to meet the following criteria: be case-control design, be studied by two or more studies, not be focused on HLA antigen genetic markers and be published in English. We identified 47 studies of polymorphic variation in 16 genes and acute lymphoblastic leukemia risk. To clarify the impact of individual polymorphisms on risk, pooled analyses were performed. Of the 25 polymorphic variants studied, significant associations (P<0.05) were seen in pooled analyses for eight variants: GSTM1 (OR =1.16; 95%CI: 1.04-1.30), MTRR A66G (OR=0.73, 95%CI:0.59-0.91), SHMT1 C1420T (OR=0.79, 95%CI: 0.65-0.98), RFC1 G80A (OR=1.37, 95%CI: 1.11-1.69), CYP1A1*2A (OR=1.36, 95%CI:1.11-1.66), CYP2E1*5B (OR=1.99, 95%CI:1.32-3.00) NQO1 C609T (OR=1.24, 95%CI:1.02-1.50) and XRCC1 G28152A (OR=1.78, 95%CI:1.32-2.42). These findings should, however, be interpreted with caution as the estimated false-positive report probabilities (FPRP) for each association were not noteworthy (i.e. FPRP>0.2). While candidate gene analyses are complementary to genome-wide association studies, future analyses should be based on sample sizes commensurate with the detection of small effects and attention needs to be paid to study design.

Combined 677CC/1298AC genotypes of methylenetetrahydrofolate reductase (MTHFR ) reduce susceptibility to precursor B lymphoblastic leukemia in a Chinese population

The methylenetetrahydrofolate reductase (MTHFR) encodes a major enzyme in folate metabolism. It has been suggested that two MTHFR polymorphisms, 677C>T and 1298A>C, influence risk of acute lymphoblastic leukemia (ALL). Most studies on relation of MTHFR polymorphisms to ALL susceptibility have been in pediatric populations because ALL is relatively rare in adults. Here, we report a case-control study of 127 Chinese patients with adult precursor B lymphoblastic leukemia (B-ALL) to examine correlation between the MTHFR polymorphisms and B-ALL susceptibility in adults. Our data show that although the prevalence of genotype 1298CC was significantly higher in the female patients than in the controls (P = 0.04), the differences in distributions of combined genotypes of 1298CC with either 677CC or 677CT between the cases and the controls were statistically insignificant. Haplotype analysis revealed no significant difference between the cases and the controls. The prevalence for joint MTHFR genotypes 677CC/1298AC was significantly lower in the female B-ALL cases than in the controls [odds ratio (OR) = 0.06, 95% CI = 0.00-0.53, P = 0.0033] and no differences among the men [OR = 0.71, 95% CI = 0.20-2.53, P = 0.55], suggesting that protective effects of combined MTHFR 677CC/1298AC genotypes on susceptibility of adult B-ALL are gender bias toward women with 677CC/1298AC women being at a 17-fold reduced odds to develop B-ALL.

Methylenetetrahydrofolate reductase polymorphisms, serum methylenetetrahydrofolate reductase levels, and risk of childhood acute lymphoblastic leukemia in a Chinese population

Methylenetetrahydrofolate reductase (MTHFR), involved in DNA methylation and nucleotide synthesis, is thought to be associated with a decreased risk of adult and childhood acute lymphoblastic leukemia (ALL). Accumulating evidence has indicated that two common genetic variants, C677T and A1298C, are associated with cancer risk. We hypothesized that these two variants were associated with childhood ALL susceptibility and influence serum MTHFR levels. We genotyped these two polymorphisms and detected MTHFR levels in a case-control study of 361 cases and 508 controls. Compared with the 677CC and 677CC/CT genotypes, the 677TT genotype was associated with a statistically significantly decreased risk of childhood ALL (odds ratio = 0.53, 95% confidence interval = 0.32-0.88, and odds ratio = 0.55, 95% confidence interval = 0.35-0.88, respectively). In addition, a pronounced reduced risk of ALL was observed among low-risk ALL and B-phenotype ALL. Moreover, the mean serum MTHFR level was 8.01 ng/mL (+/-4.38) in cases and 9.27 ng/mL (+/-4.80) in controls (P < 0.001). MTHFR levels in subjects with 677TT genotype was significantly higher than those with 677CC genotype (P = 0.010) or 677CT genotype (P = 0.043) in controls. In conclusion, our results provide evidence that the MTHFR polymorphisms might contribute to reduced childhood ALL risk in this population.

Methylenetetrahydrofolate reductase genotype association with the risk of follicular lymphoma

The metabolism of folate is essential in DNA synthesis, and polymorphisms of genes involved in such metabolism have been implicated in many types of cancer. Among these, the methylene tetrahydrofolate reductase gene (MTHFR) encodes an enzyme that converts folate to a methyl donor used for DNA methylation. We studied the association between the different genotypes of the two most common MTHFR polymorphisms, C677T and A1298C, and the risk of follicular lymphoma (FL). For this purpose, 55 previously diagnosed FL patients and 170 normal control subjects were examined using polymerase chain reaction followed by restriction fragment length polymorphism. The frequency of the A1298C CC homozygous mutant genotype was significantly higher in patients with FL than in control subjects (OR = 3.51, 95% CI = 1.39-8.86, P = 0.008). No such association was found for the heterozygous A1298C AC genotype (OR = 1.08, 95% CI = 0.55-2.12, P = 0.83). On the other hand, no significant association was found for either the C677T CT heterozygous genotype (OR = 0.79, 95% CI = 0.42-1.51, P = 0.49) or the C677T TT homozygous mutant genotype (OR = 0.55, 95% CI = 0.12-2.65, P = 0.46). The present findings add to the very few reports suggesting a link between the A1298C CC homozygous MTHFR genotype and a higher risk of developing FL, and the first such in a Jordanian population.

An intronic polymorphism of IRF4 gene influences gene transcription in vitro and shows a risk association with childhood acute lymphoblastic leukemia in males

The interferon regulatory factor (IRF) family of DNA-binding proteins regulates expression of interferon-inducible genes with roles in the immune response and carcinogenesis. IRF4 is involved in the differentiation of B and T cells and is overexpressed in B-cell malignancies as a result of c-REL (NF-kappaB) hyperactivation. IRF4 polymorphisms are associated with susceptibility to chronic lymphoid leukemia (CLL) and non-Hodgkin lymphoma (NHL). We examined 13 IRF4 SNPs in 114 cases of childhood acute lymphoblastic leukemia (ALL) and 388 newborn controls from Wales (U.K.) using TaqMan assays. IRF4 intron 4 SNP rs12203592 showed a male-specific risk association (OR=4.4, 95% CI=1.5 to 12.6, P=0.007). Functional consequences of the C>T substitution at this SNP were assessed by cell-based reporter assays using three different cell lines. We found a repressive effect of the rs12203592 wildtype allele C on IRF4 promoter activity (P<0.001) but no repression by the variant allele in any cell line tested. Thus, homozygosity for the rs12203592 variant allele would result in increased IRF4 expression. This increase would be compounded by high levels of NF-kappaB activity in males due to the absence of estrogen. IRF4 differs from other IRFs in its anti-interferon activity which interferes with immune surveillance. We propose that a detailed study of IRF4 can provide information on the mechanism of the sex effect and the role of immune surveillance in childhood ALL development.

Methylenetetrahydrofolate reductase C677T and A1298C gene polymorphisms and therapy-related toxicity in children treated for acute lymphoblastic leukemia and non-Hodgkin lymphoma

This study aimed to investigate the association of the methylenetetrahydrofolate reductase (MTHFR) gene C677T and A1298C polymorphisms with serum drug levels and toxicities after high-dose methotrexate (MTX) infusion. The study included 37 children with acute lymphoblastic leukemia or non-Hodgkin lymphoma. Serum MTX levels and toxicities of bone marrow, liver and kidney were analysed. Genotype analysis of the C677T and A1298C gene polymorphisms from genomic DNA of the subjects was performed by real-time PCR. Subjects with MTHFR polymorphism for C677T (CT, TT) had significantly higher MTX levels at 24 h (p = 0.009), and these genotypes did not seem to cause toxicity. Subjects with MTHFR polymorphism for A1298C (AC, CC) had significantly higher MTX levels at 48 h (p = 0.02), and had more grade III/IV anemia (p = 0.02), thrombocytopenia (p = 0.0001), elevated AST levels (p = 0.04) and frequent febrile neutropenic episodes (p = 0.004). The present study suggests that A1298C gene, but not C677T polymorphism is associated with MTX-related toxicity.

Genetic susceptibility to childhood acute lymphoblastic leukemia shows protection in Malay boys: results from the Malaysia-Singapore ALL Study Group

To study genetic epidemiology of childhood acute lymphoblastic leukemia (ALL) in the Chinese and Malays, we investigated 10 polymorphisms encoding carcinogen- or folate-metabolism and transport. Sex-adjusted analysis showed NQO1 609CT significantly protects against ALL, whilst MTHFR 677CT confers marginal protection. Interestingly, we observed that NQO1 609CT and MTHFR 1298 C-allele have greater genetic impact in boys than in girls. The combination of SLC19A1 80GA heterozygosity and 3'-TYMS -6bp/-6bp homozygous deletion is associated with reduced ALL risk in Malay boys. Our study has suggested the importance of gender and race in modulating ALL susceptibility via the folate metabolic pathway.

Genetic susceptibility to childhood leukaemia

The aetiology of leukaemias among children is believed to be distinct from that of adults, mainly due to the clearer role for early life exposures, including those in utero. However, few risk factors have been established, because of the challenge of studying a disease with relatively low incidence. Identified risk factors, including ionizing radiation, chemotherapeutic agents and specific genetic abnormalities, explain < 10% of incidence. Although the causes for the remaining 90% are unknown, it is possible that genetic susceptibility factors, either alone or in conjunction with environmental factors, may be involved. In this paper, the authors (a) review the evidence surrounding genetic susceptibility factors, with emphasis on the genes' main effects; (b) review some recent developments in the Northern California Childhood Leukaemia Study (NCCLS) as a case study of design and practical considerations in genetic epidemiology research and (c) highlight both challenges and future directions in this exciting research area.

No association of Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in susceptibility to gallbladder cancer

Gallbladder carcinoma (GBC) is a leading cause of cancer deaths in north India. Evidence has highlighted the role of abnormal DNA methylation patterns on inappropriate gene expression in development and progression of various cancers. 5,10-Methylenetetrahydrofolate reductase (MTHFR) plays a major role in provision of methyl groups for DNA methylation. A C/T substitution in MTHFR at nucleotide 677 results in replacement of ala222-to-val in the N-terminal catalytic domain of protein, and causes considerable decrease in enzymatic activity. Thus, MTHFR C677T polymorphism may influence genetic susceptibility to GBC. The present study aimed to examine the role of C677T MTHFR polymorphism in conferring genetic susceptibility to GBC. The present study included 146 proven GBC patients and 210 healthy controls. Genotyping was done by PCR-RFLP method. The MTHFR C677T genotypes in control population were in Hardy-Weinberg equilibrium (p = ns). No statistically significant difference was observed in frequency of variant TT genotype in GBC patients in comparison to healthy controls (4.1% and 2.9%). Stratification of GBC patients on the basis of presence or absence of gallstones showed no significant association with the disease. Further, gender and age of onset of the disease did not show any significant association. In conclusion, the present study indicates that the genetic risk for GBC is not modulated by MTHFR C677T polymorphism.