Interaction between 5 genetic variants and allergy in glioma risk

Pertinence of glioma and single nucleotide polymorphism of TERT, CCDC26, CDKN2A/B and RTEL1 genes in glioma: a meta-analysis

Background

Previous genetic-epidemiological studies considered TERT (rs2736100), CCDC26 (rs4295627), CDKN2A/B (rs4977756) and RTEL1 (rs6010620) gene polymorphisms as the risk factors specific to glioma. However, the data samples of previous genetic-epidemiological studies are modest to determine whether they have definite association with glioma.

Method

The study paid attention to systematically searching databases of PubMed, Embase, Web of Science (WoS), Scopus, Cochrane Library and Google Scholars. Meta-analysis under 5 genetic models, namely recessive model (RM), over-dominant model (O-DM), allele model (AM), co-dominant model (C-DM) and dominant model (DM) was conducted for generating odds ratios (ORs) and 95% confidence intervals (CIs). That was accompanied by subgroup analyses according to various racial groups. The software STATA 17.0 MP was implemented in the study.

Result

21 articles were collected. According to data analysis results, in four genetic models (AM, RM, DM and C-DM) TERT gene rs2736100 polymorphism, CCDC26 gene rs4295627 polymorphism, CDKN2A/B gene rs4977756 polymorphism and RTEL1 gene rs6010620 polymorphisms increased the risk of glioma in Caucasians to different degrees. In Asian populations, the CCDC26 gene rs4295627 polymorphism and CDKN2A/B gene rs4977756 polymorphism did not exhibit a relevance to the risk of glioma. It is suggested to cautiously explain these results as the sample size is small.

Conclusion

The current meta-analysis suggested that the SNP of TERT (rs2736100), CCDC26 (rs4295627), CDKN2A/B (rs4977756) and RTEL1 (rs6010620) genes in glioma might increase risk of glioma, but there are ethnic differences. Further studies evaluating these polymorphisms and glioma risk are warranted.

Analysis of WDFY4 rs7097397 and PHLDB1 rs7389 polymorphisms in Chinese patients with systemic lupus erythematosus

OBJECTIVES

To explore the relationship among patient-specific SNPs from one SLE family, lupus susceptibility, and laboratory indicators in a western Chinese population.

METHODS

We previously performed whole exome sequencing in one SLE family and screened 5 SLE candidate SNPs. In this study, we verified them in 634 SLE patients and 400 healthy controls and analyzed the relationship between SNPs and laboratory indicators.

RESULTS

Among the 5 candidate SNPs, PHLDB1 rs7389T/G (dominant model, OR = 0.627, 95%CI = 0.480-0.820, P = 0.001) and WDFY4 rs7097397G/A (dominant model, OR = 0.653, 95%CI = 0.438-0.973, P = 0.035) were associated with SLE susceptibility. In addition, the G allele of rs7389 was related to an increased level of TNF-α (q = 0.013). The A allele of rs7097397 was related to reduced levels of IL-1β (q = 0.033) and IL-6 (q = 0.039) and high positive rate of antinuclear antibodies (q = 0.021).

CONCLUSIONS

Our study indicated that both the rs7389T/G and rs7097397G/A polymorphisms were related to SLE susceptibility in western China. rs7389T/G was related to increased TNF-α content, while rs7097397G/A was associated with reduced IL-1β and IL-6 content and increased antinuclear antibody positive rate. Key Points • The G allele of rs7389 was related to reduced susceptibility to SLE. • The A allele of rs7097397 was associated with reduced susceptibility to SLE. • The G allele of rs7389 was related to increased levels of TNF-α. • The A allele of rs7097397 was related to decreased concentrations of IL-1β and IL-6, as well as an increased positive rate of antinuclear antibody.

The Epidemiology of Central Nervous System Tumors

This article reviews the current epidemiology of central nervous system tumors. Population-level basic epidemiology, nationally and internationally, and current understanding of germline genetic risk are discussed, with a focus on known and well-studied risk factors related to the etiology of central nervous system tumors.

Epidemiology of Brain and Other CNS Tumors

PURPOSE OF REVIEW

Brain and other central nervous system (CNS) tumors, while rare, cause significant morbidity and mortality across all ages. This article summarizes the current state of the knowledge on the epidemiology of brain and other CNS tumors.

RECENT FINDINGS

For childhood and adolescent brain and other CNS tumors, high birth weight, non-chromosomal structural birth defects and higher socioeconomic position were shown to be risk factors. For adults, increased leukocyte telomere length, proportion of European ancestry, higher socioeconomic position, and HLA haplotypes increase risk of malignant brain tumors, while immune factors decrease risk. Although no risk factor accounting for a large proportion of brain and other CNS tumors has been discovered, the use of high throughput "omics" approaches and improved detection/measurement of environmental exposures will help us refine our current understanding of these factors and discover novel risk factors for this disease.

A meta-analysis of active smoking and risk of meningioma

INTRODUCTION

Cigarette smoking has been hypothesized to be a risk factor for meningioma. However, the results of studies exploring the relationship between smoking exposure and the occurrence of meningioma are inconsistent.

METHODS

A search of PubMed, Medline, Embase, and Science Direct (up to June 2020) databases was performed. Two authors independently extracted the data. The Newcastle–Ottawa Scale was employed for judging the quality of articles. A random-effects model was utilized for meta-analysis. Association analysis between smoking and meningioma was based on the adjusted RR and the 95% CI, as reported by eligible studies. Subgroup and sensitivity analyses were performed and publication bias was assessed. Subgroup analysis was conducted by geographical region, study design, sex, study quality, and adjustments of RR score. Begg’s and Egger’s tests were employed for detecting publication bias.

RESULTS

Twelve articles, including 2 cohort studies and 10 case–control studies, and a total of 1210167 participants were identified. The pooled relative risk (RR) with 95% confidence interval (95% CI) implied that smoking was not associated with increased risk of meningioma in men and women combined (RR=1.09; 95% CI: 0.90–1.33). From the sex-stratified subgroup analysis, the risk of meningioma was significant in men (RR=1.42; 95% CI: 1.16–1.74). Risk of meningioma in women did not remain significant (RR=0.92; 95% CI: 0.73–1.16). There was a high heterogeneity in the results (I²=58.4%, p=0.002). Sensitivity analyses showed stable results and there was no evidence of publication bias.

CONCLUSIONS

Cigarette smoking is not associated with a significantly increased risk of meningioma in the whole population, but there is a positive association in men but not in women.

Replication of GWAS identifies RTEL1, CDKN2A/B, and PHLDB1 SNPs as risk factors in Portuguese gliomas patients

Diffuse gliomas are the most common malignant primary brain tumors and remain incurable. A better knowledge of the tumor etiology is required. Specific single nucleotides polymorphisms (SNPs) rs4977756 (CDKN2A/B), rs6010620 (RTEL1), rs498872 (PHLDB1), rs2736100 (TERT), and rs4295627 (CCDC26) have been associated with glioma susceptibility and are potential risk biomarkers. This study aimed to analyze five SNPs associated with glioma susceptibility, in the Portuguese population. SNPs were genotyped using the Sequenom MassARRAY platform in 127 gliomas and 180 controls. Unconditional logistic regression models were used to calculate odds ratio (OR) and 95% confidence intervals. The false-positive report probability was also assessed. The associations between polymorphisms and survival were evaluated using the log-rank test. It was found that the AG and GG genotypes of the rs4977756 (CDKN2A/B) were associated with an increased risk of gliomas (OR 1.85 and OR 2.38) and glioblastomas (OR 2.77 and OR 3.94). The GA genotype of the rs6010620 (RTEL1) was associated with a decreased risk of glioblastomas (OR 0.45). We also observed that the GA genotype of the rs498872 (PHLDB1) was associated with an increased risk of gliomas (OR 2.92) and glioblastomas (OR 2.39). No significant risk associations were found for the rs2736100 (TERT) and rs4295627 (CCDC26). In addition, the genotype AA of the rs498872 (PHLDB1) was associated with poor overall survival of gliomas patients (AA vs. GA, p = 0.037). The rs6010620 (RTEL1), rs4977756 (CDKN2A/B), and rs498872 (PHLDB1) are associated with glioma risk in the Portuguese population and these data may contribute to understanding gliomas etiology.

The rs498872 polymorphism is associated with an elevated susceptibility to glioma: a meta-analysis of 36,264 subjects

Several genome-wide association studies have already explored the associations between rs498872 polymorphism and glioma, but the results of these studies were not consistent. Consequently, we conducted a meta-analysis of relevant studies to better analyze the effects of rs498872 polymorphism on individual susceptibility to glioma. PubMed, Web of Science and Embase were searched for eligible studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Totally, 12 studies with 36,264 subjects were analyzed. A significant association with glioma was observed for the rs498872 polymorphism in CC versus CT + TT (dominant comparison, p < 0.0001, OR = 0.81, 95% CI 0.76-0.85), TT versus CC + CT (recessive comparison, p < 0.0001, OR = 1.23, 95% CI 1.13-1.34), CT versus CC + TT (overdominant comparison, p < 0.0001, OR = 1.15, 95% CI 1.09-1.21) and C versus T (allele comparison, p < 0.0001, OR = 0.86, 95% CI 0.84-0.90). Further subgroup analyses yielded similar positive results in both Asians and Caucasians. Our findings suggested that the rs498872 polymorphism may serve as a potential genetic biomarker of glioma in both Asians and Caucasians.

The TERT rs2736100 polymorphism increases cancer risk: A meta-analysis

Abnormal telomerase activity is implicated in cancer initiation and development. The rs2736100 T > G polymorphism in the telomerase reverse transcriptase (TERT) gene, which encodes the telomerase catalytic subunit, has been associated with increased cancer risk. We conducted a meta-analysis to more precisely assess this association. After a comprehensive literature search of the PubMed and EMBASE databases up to November 1, 2016, 61 articles with 72 studies comprising 108,248 cases and 161,472 controls were included in our meta-analysis. Studies were conducted on various cancer types. The TERT rs2736100 polymorphism was associated with increased overall cancer risk in five genetic models [homozygous model (GG vs. TT): odds ratio (OR) = 1.39, 95% confidence interval (95% CI) = 1.26-1.54, P < 0.001; heterozygous model (TG vs. TT): OR = 1.16, 95% CI = 1.11-1.23, P < 0.001; dominant model (TG + GG vs. TT): OR = 1.23, 95% CI = 1.15-1.31, P < 0.001; recessive model (GG vs. TG + TT): OR = 1.25, 95% CI = 1.16-1.35, P < 0.001; and allele contrast model (G vs. T): OR = 1.17, 95% CI = 1.12-1.23, P < 0.001]. A stratified analysis based on cancer type associated the polymorphism with elevated risk of thyroid cancer, bladder cancer, lung cancer, glioma, myeloproliferative neoplasms, and acute myeloid leukemia. Our results confirm that the TERT rs2736100 polymorphism confers increased overall cancer risk.

Telomerase Reverse Transcriptase Polymorphism rs2736100: A Balancing Act between Cancer and Non-Cancer Disease, a Meta-Analysis

The enzyme telomerase reverse transcriptase (TERT) is essential for telomere maintenance. In replicating cells, maintenance of telomere length is important for the preservation of vital genetic information and prevention of genomic instability. A common genetic variant in TERT, rs2736100 C/A, is associated with both telomere length and multiple diseases. Carriage of the C allele is associated with longer telomere length, while carriage of the A allele is associated with shorter telomere length. Furthermore, some diseases have a positive association with the C and some with the A allele. In this study, meta-analyses were performed for two groups of diseases, cancerous diseases, e.g., lung cancer and non-cancerous diseases, e.g., pulmonary fibrosis, using data from genome-wide association studies and case-control studies. In the meta-analysis it was found that cancer positively associated with the C allele (pooled OR 1.16 [95% CI 1.09–1.23]) and non-cancerous diseases negatively associated with the C allele (pooled OR 0.81 [95% CI 0.65–0.99]). This observation illustrates that the ambiguous role of telomere maintenance in disease hinges, at least in part, on a single locus in telomerase genes. The dual role of this single nucleotide polymorphism also emphasizes that therapeutic agents aimed at influencing telomere maintenance should be used with caution.

The correlations between DNA methylation and polymorphisms in the promoter region of the human telomerase reverse transcriptase (hTERT) gene with postoperative recurrence in patients with thyroid carcinoma (TC)

Background

This study aims at exploring the correlations between DNA methylation and polymorphisms in the promoter region of the human telomerase reverse transcriptase (hTERT) gene and postoperative recurrence in patients with thyroid carcinoma (TC).

Methods

A total of 312 patients diagnosed with TC were chosen for the study and categorized into recurrence (n = 75) and non-recurrence (n = 237) groups. The hTERT rs2736100 and rs2736098 polymorphisms were detected by performing polymerase chain reaction-restriction fragment length polymorphism. DNA methylation in the promoter region of hTERT gene was evaluated by pyrosequencing. A telephonic and/or outpatient follow-up was conducted for all patients. The correlations of DNA methylation and polymorphisms in the promoter region of hTERT with postoperative recurrence of TC patients underwent analysis.

Results

The patient in the recurrence group showed evidently different pathological types and tumor stages in comparison to the non-recurrence group. The GG genotype of hTERT rs2736100 might increase the recurrence risk of TC patients. No correlations between hTERT rs2736098 polymorphisms and recurrence risk were observed. Compared to the TT + TG genotype frequency, the rs2736100 GG genotype frequency increased in patients without multicentricity, patients with extrathyroidal invasion, patients with lymph node metastasis, patients with undifferentiated carcinoma, and patients in the III + IV stage. The recurrence group showed significantly higher DNA methylation level compared to the non-recurrence group. The DNA methylation level was closely associated to tumor stage and lymph node metastasis of TC patients in the recurrence group.

Conclusions

The DNA methylation and rs2736100 polymorphisms in the promoter region of hTERT gene might be in correlation to postoperative recurrence of TC patients.

Association of the CCDC26 rs4295627 polymorphism with the risk of glioma: Evidence from 7,290 cases and 11,630 controls

Published data on the association between the coiled-coil domain-containing 26 (CCDC26) rs4295627 polymorphism and the risk of glioma have been inconclusive. To further investigate this association, a meta-analysis was performed. By a comprehensive literature search using PubMed and EMBASE databases, a total of 16 case-control studies were identified for inclusion in the meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess this association. Our results confirmed that the risk with allele G was higher compared with that with allele T for glioma. The results indicated that the allele G of rs4295627 polymorphism in the CCDC26 gene was associated with increased risk of glioma in the homozygote model (GG vs. TT, OR=1.936, 95 %CI: 1.500-2.658, P<0.001), the heterozygote model (GT vs. TT, OR=1.323, 95% CI: 1.241-1.412, P=0.206), the dominant model (GG+GT vs. TT, OR=1.375, 95% CI: 1.256-1.505, P=0.026), the recessive model (GG vs. GT+TT, OR=1.769, 95% CI: 1.302-2.403, P<0.001) and the allele model (G vs. T, OR=1.310, 95% CI: 1.185-1.448, P<0.001). Current evidence suggests that the rs4295627 polymorphism in the CCDC26 gene may contribute to glioma susceptibility. However, further case-control studies are required to confirm our results.

Approaching a Scientific Consensus on the Association between Allergies and Glioma Risk: A Report from the Glioma International Case-Control Study

BACKGROUND

Several previous studies have found inverse associations between glioma susceptibility and a history of allergies or other atopic conditions. Some evidence indicates that respiratory allergies are likely to be particularly relevant with regard to glioma risk. Using data from the Glioma International Case-Control Study (GICC), we examined the effects of respiratory allergies and other atopic conditions on glioma risk.

METHODS

The GICC contains detailed information on history of atopic conditions for 4,533 cases and 4,171 controls, recruited from 14 study sites across five countries. Using two-stage random-effects restricted maximum likelihood modeling to calculate meta-analysis ORs, we examined the associations between glioma and allergy status, respiratory allergy status, asthma, and eczema.

RESULTS

Having a history of respiratory allergies was associated with an approximately 30% lower glioma risk, compared with not having respiratory allergies (mOR, 0.72; 95% confidence interval, 0.58-0.90). This association was similar when restricting to high-grade glioma cases. Asthma and eczema were also significantly protective against glioma.

CONCLUSION

A substantial amount of data on the inverse association between atopic conditions and glioma has accumulated, and findings from the GICC study further strengthen the existing evidence that the relationship between atopy and glioma is unlikely to be coincidental.

IMPACT

As the literature approaches a consensus on the impact of allergies in glioma risk, future research can begin to shift focus to what the underlying biologic mechanism behind this association may be, which could, in turn, yield new opportunities for immunotherapy or cancer prevention.

Effect of CDKN2A/B rs4977756 polymorphism on glioma risk: a meta-analysis of 16 studies including 24077 participants

So far, epidemiological studies have been performed to investigate the association of CDKN2A/B rs4977756 polymorphism and glioma risk. However, the results from different studies remain inconsistent. To clarify these conflicts and to quantitatively evaluate the effect of rs4977756 polymorphism on glioma risk, a meta-analysis was conducted using relevant published clinical studies about rs4977756 polymorphisms and glioma risk. Relevant studies concerning the association between rs4977756 polymorphism and risk of glioma were included in this meta-analysis. Odds ratio (OR) and 95 % confidence interval (CI) were calculated under fixed or random effects models when appropriate. Subgroup analyses were performed by race. This meta-analysis included 13 studies with a total of 8129 cases and 15,858 controls. The pooled results showed that there was an obvious association of CDKN2A/B rs4977756 polymorphism with risk of glioma in all four comparison models (dominant model/AG + GG vs. AA: OR = 1.36, 95 %CI = 1.20-1.54, p < 0.01; heterozygote comparison/AG vs. AA: OR = 1.31, 95 %CI = 1.12-1.53, p < 0.01; homozygote comparison/GG versus AA: OR = 1.49, 95 %CI = 1.36-1.64, p < 0.01; additive model/G vs. A: OR = 1.23, 95 %CI = 1.18-1.28, p < 0.01, respectively). For the subgroup analyses of ethnicities, similar results were observed in Caucasians. However, the association was not found between rs4977756 polymorphism and the risk of glioma in all models for the Asian studies. The CDKN2A/B rs4977756 polymorphism is obvious increase the risk of glioma in Caucasians. Future studies are needed to confirm the results in other ethnic populations.

The RTEL1 rs6010620 polymorphism and glioma risk: a meta-analysis based on 12 case-control studies

BACKGROUND

The association between the RTEL1 rs6010620 single nucleotide polymorphism (SNP) and glioma risk has been extensively studied. However, the results remain inconclusive. To further examine this association, we performed a meta-analysis.

MATERIALS AND METHODS

A computerized search of the PubMed and Embase databases for publications regarding the RTEL1 rs6010620 polymorphism and glioma cancer risk was performed. Genotype data were analyzed in a meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association. Sensitivity analyses, tests of heterogeneity, cumulative meta-analyses, and assessments of bias were performed in our meta-analysis.

RESULTS

Our meta-analysis confirmed that risk with allele A is lower than with allele G for glioma. The A allele of rs6010620 in RTEL1 decreased the risk of developing glioma in the 12 case-control studies for all genetic models: the allele model (OR=0.752, 95%CI: 0.715-0.792), the dominant model (OR=0.729, 95%CI: 0.685-0.776), the recessive model (OR=0.647, 95%CI: 0.569-0.734), the homozygote comparison (OR=0.528, 95%CI: 0.456-0.612), and the heterozygote comparison (OR=0.761, 95%CI: 0.713-0.812).

CONCLUSIONS

In all genetic models, the association between the RTEL1 rs6010620 polymorphism and glioma risk was significant. This meta-analysis suggests that the RTEL1 rs6010620 polymorphism may be a risk factor for glioma. Further functional studies evaluating this polymorphism and glioma risk are warranted.

Association between RTEL1, PHLDB1, and TREH Polymorphisms and Glioblastoma Risk: A Case-Control Study

Background

Glioblastoma (GBM) is a highly invasive, aggressive, and incurable brain tumor. Genetic factors play important roles in GBM risk. The aim of this study was to elucidate the influence of gene polymorphism on GBM susceptibility.

Material/Methods

In this case-control study, we included 72 GBM patients and 320 healthy controls to analyze the association between 29 single-nucleotide polymorphisms and GBM cancer risk in the Chinese Han population. The single-nucleotide polymorphisms were determined by Sequenom MassARRAY RS1000 and statistical analysis was performed using SPSS software and SNPStats software.

Results

Using the χ² test, we found that rs2297440 and rs6010620 in RTEL1 increased risk of GBM. In the recessive model, we also found that the genotypes “CC” of rs2297440 and “GG” of rs6010620 in RTEL1 significantly increased GBM risk. The variant TT genotype of TREH rs17748 and the variant TT genotype of PHLDB1 rs498872 decreased GBM risk in the recessive model. We also found that the TREH rs17748 variant C allele showed an increased risk in males in the dominant model.

Conclusions

Our results suggest a significant association between the RETL1, TREH, and PHLDB1 genes and GBM development in the Han Chinese population.

Associations between the rs6010620 polymorphism in RTEL1 and risk of glioma: a meta-analysis of 20,711 participants

BACKGROUND

Associations between the rs6010620 polymorphism in the regulator of telomere elongation helicase1 (RTEL1) gene and glioma have been widely reported but the results were not inconclusive. The aim of the current study was to investigate the association between the rs6010620 polymorphism in RTEL1 gene and risk of glioma by meta-analysis.

MATERIALS AND METHODS

We searched PubMed, Embase, Wanfang Weipu and CNKI (China National Knowledge Infrastructure) databases, which included all research published 05 May 2014. A total of 8,292 cases and 12,419 controls from 14 case-control studies involving the rs6010620 polymorphism in the RTEL1 gene were included. Statistical analysis was performed using STATA 12.0 software.

RESULTS

The results indicated that the rs6010620 polymorphism in RTEL1 gene was indeed associated with risk of glioma (OR=1.474, 95%CI=1.282-1.694, p<0.001). On subgroup analysis by ethnicity, we found associations between the rs6010620 polymorphism in the RTEL1 gene and risk of glioma in both Caucasians and Asians.

CONCLUSIONS

The current meta-analysis suggested that the rs6010620 polymorphism in the RTEL1 gene might increase risk of glioma. In future, larger case-control studies are needed to confirm our results.

Genetic variant near TERC influencing the risk of gliomas with older age at diagnosis in a Chinese population

A recent genome-wide association study has identified an association between rs1920116 near TERC and high-grade glioma in populations of European ancestry. In order to evaluate the effect of the SNP rs1920116 near TERC in the Chinese population, we examined associations of this candidate SNP with glioma in a sample of 1970 Chinese Han individuals. SNP genotype data were available for 980 Chinese glioma patients and 990 healthy controls. Logistic regression analyses were performed to evaluate the association between rs1920116 and glioma risk adjusted for age, gender and stratified by tumor grade where appropriate. The allele G at TERC rs1920116 are risk factors for gliomas, and its association with glioma risk was consistent across tumor subgroups in the Chinese Han population (OR = 1.18-1.21). In order to assess variation in SNP effect size at different patient ages, glioma cases and controls were divided into 3 age strata, in years: <50, 50-59, and 60+. The results of multiple logistic regression analyses indicate that the SNP has age-specific effects on the risk of developing glioma. Our report confirmed the effects of rs1920116 near TERC on glioma occurring in older peoples in the Chinese Han population for the first time. As TERC is a candidate for inter-individual variation in telomere length, our study supports the hypothesis that telomerase-related mechanisms of telomere maintenance are more associated with gliomas that develop later in life.

Human cells contain natural double-stranded RNAs with potential regulatory functions

Recent evidence has suggested the existence of sense-antisense transcription in mammals, but the existence of double-stranded RNAs endowed with biological function has remained elusive. Herein we show that hundreds of putative natural double-stranded RNAs (ndsRNAs) are expressed from interspersed genomic locations and respond to cellular cues. We demonstrate that a subset of ndsRNAs localize in the nucleus and, in their double-stranded form, interact with nuclear proteins. Detailed characterization of an ndsRNA (nds-2a) revealed that this molecule displays differential localization throughout the cell cycle and directly interacts with RCC1 and RAN and, through the latter, with the mitotic RANGAP1-SUMO1-RANBP2 complex. Notably, altering nds-2a levels led to postmitotic abnormalities, mitotic catastrophe and cell death, thus supporting a mitosis-related role. Altogether, our study reveals a hitherto-unrecognized class of RNAs that potentially participate in major biological processes in human cells.

The long-term risk of malignant astrocytic tumors after structural brain injury--a nationwide cohort study

BACKGROUND

Neoplastic transformation of damaged astrocytes has been proposed as a possible pathological mechanism behind malignant astrocytic tumors. This study investigated the association between structural brain injuries causing reactive astrogliosis and long-term risk for malignant astrocytic tumors.

METHODS

The cohort consisted of all individuals living in Denmark between 1978 and 2011. The personal identification number assigned to all individuals allowed retrieval of diagnoses of traumatic brain injury, cerebral ischemic infarction, and intracerebral hemorrhage from the National Patient Discharge Register. Diagnoses of anaplastic astrocytoma and glioblastoma multiforme (World Health Organization grades III and IV) were retrieved from the Danish Cancer Registry. Rate ratios (RR's) were estimated using log-linear Poisson regression.

RESULTS

In a cohort of 8.2 million individuals, 404 812 experienced a structural brain injury and 6152 developed a malignant astrocytic tumor. No significant association was observed 1-4 years after a structural brain injury (RR = 1.14; 95% CI: 0.87-1.46), whereas the long-term (5+ y) risk for malignant astrocytic tumors was significantly reduced (RR = 0.68; 95% CI: 0.49-0.90) compared with no injury. The specific long-term risks by type of injury were: traumatic brain injury RR = 0.32 (95% CI: 0.10-0.75); cerebral ischemic infarction RR = 0.69 (95% CI: 0.47-0.96); and intracerebral hemorrhage RR = 1.39 (95% CI: 0.64-2.60).

CONCLUSION

We found no evidence for an association between structural brain injury and malignant astrocytic tumors within the first 5 years of follow-up. However, our study indicated a protective effect of astrogliosis-causing injuries 5 or more years after structural brain injury.

The epidemiology of glioma in adults: a "state of the science" review

Gliomas are the most common primary intracranial tumor, representing 81% of malignant brain tumors. Although relatively rare, they cause significant mortality and morbidity. Glioblastoma, the most common glioma histology (∼45% of all gliomas), has a 5-year relative survival of ∼5%. A small portion of these tumors are caused by Mendelian disorders, including neurofibromatosis, tuberous sclerosis, and Li-Fraumeni syndrome. Genomic analyses of glioma have also produced new evidence about risk and prognosis. Recently discovered biomarkers that indicate improved survival include O⁶-methylguanine-DNA methyltransferase methylation, isocitrate dehydrogenase mutation, and a glioma cytosine-phosphate-guanine island methylator phenotype. Genome-wide association studies have identified heritable risk alleles within 7 genes that are associated with increased risk of glioma. Many risk factors have been examined as potential contributors to glioma risk. Most significantly, these include an increase in risk by exposure to ionizing radiation and a decrease in risk by history of allergies or atopic disease(s). The potential influence of occupational exposures and cellular phones has also been examined, with inconclusive results. We provide a “state of the science” review of current research into causes and risk factors for gliomas in adults.

The PHLDB1 rs498872 (11q23.3) polymorphism and glioma risk: A meta-analysis

The association between the rs498872 single nucleotide polymorphism (SNP) and glioma risk has been studied, but these studies have yielded conflicting results. In order to explore this association, we performed a meta-analysis. A comprehensive literature search was performed using PubMed and EMBASE database, with the last search up to August 23, 2013. Six articles including 10 case-control studies in English with 18 002 controls and 8434 cases were eligible for the meta-analysis. Subgroup analyses were conducted by source of controls and ethnicity. The combined results showed that rs498872 polymorphism was significantly associated with glioma risks (TT vs CC: OR = 1.337, 95% CI = 1.222-1.462; TC vs CC: OR = 1.173, 95% CI = 1.081-1.272; dominant model: OR = 1.199, 95% CI = 1.101-1.306; recessive model: OR = 1.237, 95% CI = 1.135-1.347; additive model: OR = 1.156, 95% CI = 1.085-1.232). Moreover, there was increased cancer risk in all genetic models after stratification of the SNP data by the source of controls and ethnicity, and no evidence of publication bias was produced. Our meta-analysis suggested that rs498872 polymorphism was associated with increased risk of glioma. However, additional studies exploring the combined effects of rs498872 polymorphisms in Asian population should be investigated.

Atopic conditions and brain tumor risk in children and adolescents--an international case-control study (CEFALO)

BACKGROUND

A number of epidemiological studies indicate an inverse association between atopy and brain tumors in adults, particularly gliomas. We investigated the association between atopic disorders and intracranial brain tumors in children and adolescents, using international collaborative CEFALO data.

PATIENTS AND METHODS

CEFALO is a population-based case-control study conducted in Denmark, Norway, Sweden, and Switzerland, including all children and adolescents in the age range 7-19 years diagnosed with a primary brain tumor between 2004 and 2008. Two controls per case were randomly selected from population registers matched on age, sex, and geographic region. Information about atopic conditions and potential confounders was collected through personal interviews.

RESULTS

In total, 352 cases (83%) and 646 controls (71%) participated in the study. For all brain tumors combined, there was no association between ever having had an atopic disorder and brain tumor risk [odds ratio 1.03; 95% confidence interval (CI) 0.70-1.34]. The OR was 0.76 (95% CI 0.53-1.11) for a current atopic condition (in the year before diagnosis) and 1.22 (95% CI 0.86-1.74) for an atopic condition in the past. Similar results were observed for glioma.

CONCLUSIONS

There was no association between atopic conditions and risk of all brain tumors combined or of glioma in particular. Stratification on current or past atopic conditions suggested the possibility of reverse causality, but may also the result of random variation because of small numbers in subgroups. In addition, an ongoing tumor treatment may affect the manifestation of atopic conditions, which could possibly affect recall when reporting about a history of atopic diseases. Only a few studies on atopic conditions and pediatric brain tumors are currently available, and the evidence is conflicting.

Association between telomerase reverse transcriptase rs2736100 polymorphism and risk of glioma

BACKGROUND

Epidemiological studies have been conducted to investigate the association of telomerase reverse transcriptase (TERT) rs2736100 polymorphism with glioma risk. The aim of the present study was to evaluate the association of TERT rs2736100 polymorphism with glioma risk using a meta-analysis approach.

MATERIALS AND METHODS

All eligible studies were identified through a search of PubMed, EMBASE, China National Knowledge Infrastructure, Database of Chinese Scientific and Technical Periodicals, and China Biology Medical literature database before January 2014. The association between the TERT rs2736100 polymorphism and glioma risk was estimated by odds ratio (OR) and 95% confidence interval (CI).

RESULTS

A total of nine case-control studies including 9411 cases and 13,708 controls were eventually collected. Overall, we found that TERT rs2736100 polymorphism was significantly associated with the risk of glioma (OR = 1.29, 95% CI 1.24-1.34, P < 0.001). In the subgroup analysis based on ethnicity, the significant association was found in Caucasians (OR = 1.29, 95% CI 1.24-1.34, P < 0.001). In subgroup analyses by histology, the associations were significant in glioblastoma (OR = 1.45, 95% CI 1.32-1.60, P < 0.001), astrocytoma (OR = 1.41, 95% CI 1.26-1.58, P < 0.001), and oligodendroglioma (OR = 1.20, 95% CI 1.05-1.37, P = 0.008).

CONCLUSIONS

Taken together, these data suggested that TERT rs2736100 polymorphism may contribute to glioma susceptibility.

Immune-related conditions and subsequent risk of brain cancer in a cohort of 4.5 million male US veterans

Background:

Case–control studies have reported an inverse association between self-reported history of allergy and risk of glioma, but cohort data are limited. Our objectives were to evaluate the associations of major groups of medically diagnosed immune-related conditions (allergy/atopy, autoimmune disease, diabetes, infectious/inflammatory disease) and to explore associations with specific conditions in relation to subsequent diagnosis of brain cancer in a large cohort study.

Methods:

We used hospital discharge records for a cohort of 4.5 million male US veterans, of whom 4383 developed primary brain cancer. Rate ratios (RRs) and 95% confidence intervals (CIs) were calculated using time-dependent Poisson regression.

Results:

We found a significant trend of decreasing RRs for brain cancer with longer duration of allergy/atopy (P=0.02), but not for other conditions studied. Rate ratios of brain cancer for allergy/atopy and diabetes with duration of 10 or more years were 0.60 (95% CI: 0.43, 0.83) and 0.75 (95% CI: 0.62, 0.93), respectively. Several associations with specific conditions were found, but these did not withstand correction for multiple comparisons.

Conclusions:

This study lends some support to an inverse association between allergy/atopy and diabetes of long duration and brain cancer risk, but prospective studies with biological samples are needed to uncover the underlying biological mechanisms.

Regulator of telomere elongation helicase 1 (RTEL1) rs6010620 polymorphism contribute to increased risk of glioma

Regulator of telomere elongation helicase 1 (RTEL1) is critical for genome stability and tumor avoidance. Many studies have reported the associations of RTEL1 rs6010620 with glioma risk, but individually published results were inconclusive. This meta-analysis was performed to quantitatively summarize the evidence for such a relationship. The PubMed, Embase, and Web of Science were systematically searched to identify relevant studies. The odds ratio (OR) and 95 % confidence interval (95 % CI) were computed to estimate the strength of the association using a fixed or random effects model. Ten studies were eligible for meta-analysis including data on glioma with 6,490 cases and 9,288 controls. Overall, there was a significant association between RTEL1 rs6010620 polymorphism and glioma risk in all four genetic models (GG vs. AA: OR=1.87, 95 % CI=1.60-2.18, P heterogeneity=0.552; GA vs. AA: OR=1.30, 95 % CI=1.16-1.46, P heterogeneity=0.495; dominant model-GG+GA vs. AA: OR=1.46, 95 % CI=1.31-1.63, P heterogeneity=0.528; recessive model-GG vs. GA+AA: OR=1.36, 95 % CI=1.27-1.46, P heterogeneity=0.093). Subgroup analyses by ethnicity showed that RTEL1 rs6010620 polymorphism resulted in a higher risk of glioma among both Asians and Caucasians. In the stratified analysis by ethnicity and source of controls, significantly increased risk was observed for Asians and Europeans in all genetic models, population-based studies in all genetic models, and hospital-based studies in three genetic models (heterozygote comparison, homozygote comparison, and dominant model). Our meta-analysis suggested that RTEL1 rs6010620 polymorphism is likely to be associated with increased glioma risk, which lends further biological plausibility to these findings.

Joint effects between five identified risk variants, allergy, and autoimmune conditions on glioma risk

Common variants in two of the five genetic regions recently identified from genome-wide association studies (GWAS) of risk of glioma were reported to interact with a history of allergic symptoms. In a pooled analysis of five epidemiologic studies, we evaluated the association between the five GWAS implicated gene variants and allergies and autoimmune conditions (AIC) on glioma risk (851 adult glioma cases and 3,977 controls). We further evaluated the joint effects between allergies and AIC and these gene variants on glioma risk. Risk estimates were calculated as odds ratios (OR) and 95 % confidence intervals (95 % CI), adjusted for age, gender, and study. Joint effects were evaluated by conducting stratified analyses whereby the risk associations (OR and 95 % CI) with the allergy or autoimmune conditions for glioma were evaluated by the presence or absence of the 'at-risk' variant, and estimated p interaction by fitting models with the main effects of allergy or autoimmune conditions and genotype and an interaction (product) term between them. Four of the five SNPs previously reported by others were statistically significantly associated with increased risk of glioma in our study (rs2736100, rs4295627, rs4977756, and rs6010620); rs498872 was not associated with glioma in our study. Reporting any allergies or AIC was associated with reduced risks of glioma (allergy: adjusted OR = 0.71, 95 % CI 0.55-0.91; AIC: adjusted OR = 0.65, 95 % CI 0.47-0.90). We did not observe differential association between allergic or autoimmune conditions and glioma by genotype, and there were no statistically significant p interactions. Stratified analysis by glioma grade (low and high grade) did not suggest risk differences by disease grade. Our results do not provide evidence that allergies or AIC modulate the association between the four GWAS-identified SNPs examined and risk of glioma.

Single-nucleotide polymorphisms of allergy-related genes and risk of adult glioma

Previous studies have shown an inverse association between allergies and glioma risk; however, results for associations between single nucleotide polymorphisms (SNPs) of allergy-related genes and glioma risk have been inconsistent and restricted to a small number of SNPs. The objective of this study was to examine the association between 166 SNPs of 21 allergy-related genes and glioma risk in a nested case-control study of participants from three large US prospective cohort studies. Blood collection took place between 1982 and 1994 among the 562 included Caucasian participants (143 cases and 419 matched controls) prior to case diagnosis. Custom Illumina assay chips were used for genotyping. Logistic regression analyses, controlling for age and study cohort, were used to determine associations between each SNP and glioma risk. Statistically significant associations were found between rs2494262 and rs2427824 of the FCER1A gene, which encodes the alpha chain of the high affinity immunoglobulin E receptor, and glioma risk (nominal trend p values 0.01 and 0.03, respectively). Significant associations were also found between SNPs in IL10, ADAM33, NOS1 and IL4R and glioma risk. However, our analyses were not corrected for multiple comparisons and need to be interpreted with caution. Our findings with FCER1A SNPs provide further support for the link between allergies and risk of glioma.

Allergy and brain tumors in the INTERPHONE study: pooled results from Australia, Canada, France, Israel, and New Zealand

PURPOSE

A history of allergy has been inversely associated with several types of cancer although the evidence is not entirely consistent. We examined the association between allergy history and risk of glioma, meningioma, acoustic neuroma, and parotid gland tumors using data on a large number of cases and controls from five INTERPHONE study countries (Australia, Canada, France, Israel, New Zealand), to better understand potential sources of bias in brain tumor case-control studies and to examine associations between allergy and tumor sites where few studies exist.

METHODS

A total of 793 glioma, 832 meningioma, 394 acoustic neuroma, and 84 parotid gland tumor cases were analyzed with 2,520 controls recruited during 2000-2004. Conditional logistic regression models were used to obtain odds ratios (ORs) and 95 % confidence intervals (CIs) for associations between self-reported allergy and tumor risk.

RESULTS

A significant inverse association was observed between a history of any allergy and glioma (OR = 0.73, 95 % CI 0.60-0.88), meningioma (OR = 0.77, 95 % CI 0.63-0.93), and acoustic neuroma (OR = 0.64, 95 % CI 0.49-0.83). Inverse associations were also observed with specific allergic conditions. However, inverse associations with asthma and hay fever strengthened with increasing age of allergy onset and weakened with longer time since onset. No overall association was observed for parotid gland tumors (OR = 1.21, 95 % CI 0.73-2.02).

CONCLUSIONS

While allergy history might influence glioma, meningioma, and acoustic neuroma risk, the observed associations could be due to information or selection bias or reverse causality.

Association of 8q24 rs13281615A > G polymorphism with breast cancer risk: evidence from 40,762 cases and 50,380 controls

The association between a single nucleotide polymorphism rs13281615A > G located in the 8q24 and breast cancer risk is still controversial and ambiguous. Hence, we performed a more convincing and precise estimation of the relationship between 8q24 and breast cancer by meta-analyzing the currently available evidence from literature. PubMed, Ovid, Medline, and Web of Science databases were searched. A total of 10 publications containing 11 studies including 40,762 cases and 50,380 controls were identified. Crude odds ratio with 95 % confidence interval was used to assess the strength of association. We observed that the 8q24 rs13281615A > G polymorphism was significantly correlated with breast cancer risk when all studies were pooled into the meta analysis. In the stratified analysis by ethnicity, significantly increased risks were also found among Caucasians for all genetic models. For mixed ethnicities, significantly increased risks were found for all genetic models except for the allele contrast model. However, no significantly increased risk was found among Africans for all genetic models. Interestingly, when stratified by BRCA1 mutation carriers status, significantly decreased breast cancer risk was found for allele contrast model. But significantly increased breast cancer risk was found in the BRCA2 mutation carriers for all genetic models except for the recessive model. There was no evidence for significant association between 8q24 rs13281615A > G polymorphism and breast cancer risk in BRCA1 and BRCA2 positive cohort in all comparable models. In conclusion, this meta-analysis suggests that the 8q24 rs13281615A > G polymorphism is a low-penetrant risk factor for developing breast cancer but may not be in Africans.

Fine mapping of a region of chromosome 11q23.3 reveals independent locus associated with risk of glioma

Background

A single nucleotide polymorphism (SNP) at locus 11q23.3 (rs498872) in the near 5′-UTR of the PHLDB1 gene was recently implicated as a risk factor for gliomas in a genome-wide association study, and this involvement was confirmed in three additional studies.

Methodology/Principal Findings

To identify possible causal variants in the region, the authors genotyped 15 tagging SNPs in the 200 kb genomic region at 11q23.3 locus in a Chinese Han population-based case-control study with 983 cases and 1024 controls. We found evidence for an association between two independent loci (both the PHLDB1 and the ACRN1 genes) and a predisposition for gliomas. Among the multiple significant SNPs in the PHLDB1 gene region, the rs17749 SNP was the most significant [P = 1.31×10⁻⁶ in a recessive genetic model]. Additionally, two novel SNPs (rs2236661 and rs494560) that were independent of rs17749 were significantly associated with glioma risk in a recessive genetic model [P = 1.31×10⁻⁵ and P = 3.32×10⁻⁵, respectively]. The second novel locus was within the ARCN1 gene, and it was associated with a significantly reduced risk for glioma.

Conclusions/Significance

Our data strongly support PHLDB1 as a susceptibility gene for glioma, also shedding light on a new potentially candidate gene, ARCN1.

Discovering gene-environment interactions in glioblastoma through a comprehensive data integration bioinformatics method

Glioblastoma multiforme (GBM) is the most common and aggressive type of human brain tumor. Although considerable efforts to delineate the underlying pathophysiological pathways have been made during the last decades, only very limited progress on treatment have been achieved because molecular pathways that drive the aggressive nature of GBM are largely unknown. Recent studies have emphasized the importance of environmental factors and the role of gene-environment interactions (GEI) in the development of GBM. Factors such as small sample sizes and study costs have limited the conduct of GEI studies in brain tumors however. Additionally, advances in high-throughput microarrays have produced a wealth of information concerning molecular biology of glioma. In particular, microarrays have been used to obtain genetic and epigenetic changes between normal non-tumor tissue and glioma tissue. Due to the relative rarity of gliomas, microarray data for these tumors is often the product of small studies, and thus pooling this data becomes desirable. To address the challenge of small sample sizes and GEI study difficulties, we introduce a comprehensive bioinformatics method using genetic variations (copy number variations and small-scale variations) and environmental data integration that links with glioblastoma (GEG) to identify: (1) genes that interact with chemicals and have genetic variants linked to the development of GBM, (2) important pathways that may be influenced by environmental exposures (or endogenous chemicals), and (3) genes with variants in GBM that have been understudied in relation to GBM development. The first step in our GEG method identified genes responsive to environmental exposures using the Environmental Genome Project, Comparative Toxicology, and Seattle SNPs databases. These environmentally responsive genes were then compared to a curated list of genes containing copy number variation and/or mutations in GBM. This comparison produced a list of genes responsive to the environment and important to GBM that was then further analyzed using gene networking tools such as RSpider, Cytoscape, and DAVID. Using this GEG bioinformatics method we were able to identify 173 genes with the potential to be involved in GEI that may be important to the development of GBM. Sixty five of these environmentally responsive genes have not been reported as important to GBM development, despite several of them having substantial potential for response to chemicals and subsequent disease related actions. The main biological functions of these 173 genes include signaling by nerve growth factor, DNA repair, integrin cell surface interactions, biological oxidations, apoptosis, synaptic transmission, cell cycle checkpoints, and arachidonic acid metabolism. Importantly, some of these functions have been implicated in the development of several cancers, including glioma. In summary, our GEG bioinformatics approach revealed potential gene-environment interactions, and generated new data for hypothesis generation, in GBM.

Leveraging ethnic group incidence variation to investigate genetic susceptibility to glioma: a novel candidate SNP approach

Objectives: Using a novel candidate SNP approach, we aimed to identify a possible genetic basis for the higher glioma incidence in Whites relative to East Asians and African-Americans. Methods:  We hypothesized that genetic regions containing SNPs with extreme differences in allele frequencies across ethnicities are most likely to harbor susceptibility variants. We used International HapMap Project data to identify 3,961 candidate SNPs with the largest allele frequency differences in Whites compared to East Asians and Africans and tested these SNPs for association with glioma risk in a set of White cases and controls. Top SNPs identified in the discovery dataset were tested for association with glioma in five independent replication datasets. Results: No SNP achieved statistical significance in either the discovery or replication datasets after accounting for multiple testing or conducting meta-analysis. However, the most strongly associated SNP, rs879471, was found to be in linkage disequilibrium with a previously identified risk SNP, rs6010620, in RTEL1. We estimate rs6010620 to account for a glioma incidence rate ratio of 1.34 for Whites relative to East Asians. Conclusion: We explored genetic susceptibility to glioma using a novel candidate SNP method which may be applicable to other diseases with appropriate epidemiologic patterns.

Epidemiology: allergy history, IgE, and cancer

Numerous epidemiological studies have investigated potential associations between allergy history and cancer risk with strong inverse associations reported in studies of pancreatic cancer, glioma, and childhood leukemia. Recently, there has been a rapid expansion of the epidemiological literature both of studies evaluating self-reported allergy history in relation to cancer risk and of studies evaluating biological indicators of allergy history and immune function including levels of immunoglobulin (Ig) E. However, there are several potential methodological limitations associated with prior studies, and further research is required to clarify associations observed. This paper summarizes the recent epidemiological literature examining associations between allergy history and cancer risk. From 2008, a total of 55 epidemiological studies were identified that examined some aspect of the association between allergy and cancer. Although the majority of studies examined self-reported allergy history in relation to cancer risk, there were also studies examining allergy diagnoses or discharges as captured in existing administrative databases, levels of IgE, polymorphisms of allergy, inflammatory- or allergy-related cytokine genes, and concentrations of immune regulatory proteins. The most frequently studied cancer sites included brain and lymphatic and hematopoietic cancers. Potential methodological sources of bias are discussed as well as recommendations for future work.

Genome-wide association study of glioma and meta-analysis

Gliomas account for approximately 80 % of all primary malignant brain tumors and, despite improvements in clinical care over the last 20 years, remain among the most lethal tumors, underscoring the need for gaining new insights that could translate into clinical advances. Recent genome-wide association studies (GWAS) have identified seven new susceptibility regions. We conducted a new independent GWAS of glioma using 1,856 cases and 4,955 controls (from 14 cohort studies, 3 case-control studies, and 1 population-based case-only study) and found evidence of strong replication for three of the seven previously reported associations at 20q13.33 (RTEL), 5p15.33 (TERT), and 9p21.3 (CDKN2BAS), and consistent association signals for the remaining four at 7p11.2 (EGFR both loci), 8q24.21 (CCDC26) and 11q23.3 (PHLDB1). The direction and magnitude of the signal were consistent for samples from cohort and case-control studies, but the strength of the association was more pronounced for loci rs6010620 (20q,13.33; RTEL) and rs2736100 (5p15.33, TERT) in cohort studies despite the smaller number of cases in this group, likely due to relatively more higher grade tumors being captured in the cohort studies. We further examined the 85 most promising single nucleotide polymorphism (SNP) markers identified in our study in three replication sets (5,015 cases and 11,601 controls), but no new markers reached genome-wide significance. Our findings suggest that larger studies focusing on novel approaches as well as specific tumor subtypes or subgroups will be required to identify additional common susceptibility loci for glioma risk.

The TERT rs2736100 polymorphism and cancer risk: a meta-analysis based on 25 case-control studies

Background

The association between the TERT rs2736100 single nucleotide polymorphism (SNP) and cancer risk has been studied by many researchers, but the results remain inconclusive. To further explore this association, we performed a meta-analysis.

Methods

A computerized search of PubMed and Embase database for publications on the TERT rs2736100 polymorphism and cancer risk was performed and the genotype data were analyzed in a meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association. Sensitivity analysis, test of heterogeneity, cumulative meta-analysis and assessment of bias were performed in our meta-analysis.

Results

A significant association between the TERT rs2736100 polymorphism and cancer susceptibility was revealed by the results of the meta-analysis of the 25 case-control studies (GG versus TT: OR = 1.72, 95% CI: 1.58, 1.88; GT versus TT: OR = 1.38, 95% CI: 1.29, 1.47; dominant model-TG + GG versus TT: OR = 1.47, 95% CI: 1.37, 1.58; recessive model-GG versus TT + TG: OR = 1.37, 95% CI 1.31, 1.43; additive model-2GG + TG versus 2TT + TG: OR = 1.30, 95% CI: 1.25, 1.36). Moreover, increased cancer risk in all genetic models was found after stratification of the SNP data by cancer type, ethnicity and source of controls.

Conclusions

In all genetic models, the association between the TERT rs2736100 polymorphism and cancer risk was significant. This meta-analysis suggests that the TERT rs2736100 polymorphism may be a risk factor for cancer. Further functional studies between this polymorphism and cancer risk are warranted.

Meta-analysis of 8q24 for seven cancers reveals a locus between NOV and ENPP2 associated with cancer development

Background

Human chromosomal region 8q24 contains several genes which could be functionally related to cancer, including the proto-oncogene c-MYC. However, the abundance of associations around 128 Mb on chromosome 8 could mask the appearance of a weaker, but important, association elsewhere on 8q24.

Methods

In this study, we completed a meta-analysis of results from nine genome-wide association studies for seven types of solid-tumor cancers (breast, prostate, pancreatic, lung, ovarian, colon, and glioma) to identify additional associations that were not apparent in any individual study.

Results

Fifteen SNPs in the 8q24 region had meta-analysis p-values < 1E-04. In particular, the region consisting of 120,576,000-120,627,000 bp contained 7 SNPs with p-values < 1.0E-4, including rs6993464 (p = 1.25E-07). This association lies in the region between two genes, NOV and ENPP2, which have been shown to play a role in tumor development and motility. An additional region consisting of 5 markers from 128,478,000 bp - 128,524,000 (around gene POU5F1B) had p-values < 1E-04, including rs6983267, which had the smallest p-value (p = 6.34E-08). This result replicates previous reports of association between rs6983267 and prostate and colon cancer.

Conclusions

Further research in this area is warranted as these results demonstrate that the chromosomal region 8q24 may contain a locus that influences general cancer susceptibility between 120,576 and 120,630 kb.

Joint associations between genetic variants and reproductive factors in glioma risk among women

In a pooled analysis of 4 US epidemiologic studies (1993-2001), the authors evaluated the role of 5 female reproductive factors in 357 women with glioma and 822 controls. The authors further evaluated the independent association between 5 implicated gene variants and glioma risk among the study population, as well as the joint associations of female reproductive factors (ages at menarche and menopause, menopausal status, use of oral contraceptives, and menopausal hormone therapy) and these gene variants on glioma risk. Risk estimates were calculated as odds ratios and 95% confidence intervals that were adjusted for age, race, and study. Three of the gene variants (rs4295627, a variant of CCDC26; rs4977756, a variant of CDKN2A and CDKN2B; and rs6010620, a variant of RTEL1) were statistically significantly associated with glioma risk in the present population. Compared with women who had an early age at menarche (<12 years of age), those who reported menarche at 12-13 years of age or at 14 years of age or older had a 1.7-fold higher risk and a 1.9-fold higher risk of glioma, respectively (P for trend = 0.009). Postmenopausal women and women who reported ever having used oral contraceptives had a decreased risk of glioma. The authors did not observe joint associations between these reproductive characteristics and the implicated glioma gene variants. These results require replication, but if confirmed, they would suggest that the gene variants that have previously been implicated in the development of glioma are unlikely to act through the same hormonal mechanisms in women.

Associations of high-grade glioma with glioma risk alleles and histories of allergy and smoking

Glioma risk has consistently been inversely associated with allergy history but not with smoking history despite putative biologic plausibility. Data from 855 high-grade glioma cases and 1,160 controls from 4 geographic regions of the United States during 1997-2008 were analyzed for interactions between allergy and smoking histories and inherited variants in 5 established glioma risk regions: 5p15.3 (TERT), 8q24.21 (CCDC26/MLZE), 9p21.3 (CDKN2B), 11q23.3 (PHLDB1/DDX6), and 20q13.3 (RTEL1). The inverse relation between allergy and glioma was stronger among those who did not (odds ratio(allergy-glioma) = 0.40, 95% confidence interval: 0.28, 0.58) versus those who did (odds ratio(allergy-glioma) = 0.76, 95% confidence interval: 0.59, 0.97; P(interaction) = 0.02) carry the 9p21.3 risk allele. However, the inverse association with allergy was stronger among those who carried (odds ratio(allergy-glioma) = 0.44, 95% confidence interval: 0.29, 0.68) versus those who did not carry (odds ratio(allergy-glioma) = 0.68, 95% confidence interval: 0.54, 0.86) the 20q13.3 glioma risk allele, but this interaction was not statistically significant (P = 0.14). No relation was observed between glioma risk and smoking (odds ratio = 0.92, 95% confidence interval: 0.77, 1.10; P = 0.37), and there were no interactions for glioma risk of smoking history with any of the risk alleles. The authors' observations are consistent with a recent report that the inherited glioma risk variants in chromosome regions 9p21.3 and 20q13.3 may modify the inverse association of allergy and glioma.