Genetic modulation of longitudinal change in neurocognitive function among adult glioma patients.

PURPOSE: Impaired neurocognitive function (NCF) is extremely common in patients with higher grade primary brain tumor. We previously reported evidence of genetic variants associated with NCF in glioma patients prior to treatment. However, little is known about the effect of genetic variants on NCF decline after adjuvant therapy. METHODS: Patients (N = 102) completed longitudinal NCF assessments that included measures of verbal memory, processing speed, and executive function. Testing was conducted in the postoperative period with an average follow up interval of 1.3 years. We examined polymorphisms in 580 genes related to five pathways (inflammation, DNA repair, metabolism, cognitive, and telomerase). RESULTS: Five polymorphisms were associated with longitudinal changes in processing speed and 14 polymorphisms with executive function. Change in processing speed was strongly associated with MCPH1 rs17631450 (P = 2.2 × 10-7) and CCDC26 rs7005206 (P = 9.3 × 10-7) in the telomerase pathway; while change in executive function was more strongly associated with FANCF rs1514084 (P = 2.9 × 10-6) in the DNA repair pathway and DAOA rs12428572 (P = 2.4 × 10-5) in the cognitive pathway. Joint effect analysis found significant genetic-dosage effects for longitudinal changes in processing speed (Ptrend = 1.5 × 10-10) and executive function (Ptrend = 2.1 × 10-11). In multivariable analyses, predictors of NCF decline included progressive disease, lower baseline NCF performance, and more at-risk genetic variants, after adjusting for age, sex, education, tumor location, histology, and disease progression. CONCLUSION: Our longitudinal analyses revealed that polymorphisms in telomerase, DNA repair, and cognitive pathways are independent predictors of decline in NCF in glioma patients.

Comparative effectiveness of first-line tumour necrosis factor inhibitor versus non-tumour necrosis factor inhibitor biologics and targeted synthetic agents in patients with rheumatoid arthritis: results from a large US registry study.

OBJECTIVES: This study evaluated the comparative effectiveness of a tumour necrosis factor inhibitor (TNFi) versus a non-TNFi (biological disease-modifying antirheumatic drugs (bDMARDs) and targeted synthetic DMARDs (tsDMARDs)) as the first-line treatment following conventional synthetic DMARDs, as well as potential modifiers of response, observed in US clinical practice. METHODS: Data were from a large US healthcare registry (Consortium of Rheumatology Researchers of North America Rheumatoid Arthritis Registry). The analysis included patients (aged ≥18 years) with a documented diagnosis of rheumatoid arthritis (RA), a valid baseline Clinical Disease Activity Index (CDAI) score of >2.8 and no prior bDMARD or tsDMARD use. Outcomes were captured at 1-year postinitiation of a TNFi (adalimumab, etanercept, certolizumab pegol, golimumab or infliximab) or a non-TNFi (abatacept, tocilizumab, rituximab, anakinra or tofacitinib) and included CDAI, 28-Joint Modified Disease Activity Score, patient-reported outcomes (including the Health Assessment Questionnaire Disability Index, EuroQol-5 Dimension score, sleep, anxiety, morning stiffness and fatigue) and rates of anaemia. Groups were propensity score-matched at baseline to account for potential confounding. RESULTS: There were no statistically significant differences observed between the TNFi and non-TNFi treatment groups for outcomes assessed, except the incidence rate ratio for anaemia, which slightly favoured the TNFi group (19.04 per 100 person-years) versus the non-TNFi group (24.01 per 100 person-years, p=0.03). No potential effect modifiers were found to be statistically significant. CONCLUSIONS: The findings of no significant differences in outcomes between first-line TNF versus first-line non-TNF groups support RA guidelines, which recommend individualised care based on clinical judgement and consideration of patient preferences.

Adjustment of the multi-biomarker disease activity score to account for age, sex and adiposity in patients with rheumatoid arthritis.

OBJECTIVE: To develop and evaluate an adjusted score for the multi-biomarker disease activity (MBDA) test to account for the effects of age, sex and adiposity in patients with RA. METHODS: Two models were developed to adjust MBDA score for age, sex and adiposity, using either serum leptin concentration or BMI as proxies for adiposity. Two cohorts were studied. A cohort of 325 781 RA patients who had undergone commercial MBDA testing and had data for age, sex and serum leptin concentration was used for both models. A cohort of 1411 patients from five studies/registries with BMI data was used only for the BMI-adjusted MBDA score. Univariate and multivariate linear regression analyses evaluated the adjusted MBDA scores and conventional clinical measures as predictors of radiographic progression, assessed in terms of modified total Sharp score (ΔmTSS). RESULTS: Two models were developed, based on findings that MBDA score was higher in females than males and increased with age, leptin concentration and BMI. In pairwise regression analyses, the leptin-adjusted (P = 0.00066) and BMI-adjusted (P = 0.0027) MBDA scores were significant independent predictors of ΔmTSS after adjusting for DAS28-CRP, whereas DAS28-CRP was not, after adjusting for leptin-adjusted (P = 0.74) or BMI-adjusted (P = 0.87) MBDA score. Moreover, the leptin-adjusted MBDA score was a significant predictor of ΔmTSS after adjusting for the BMI-adjusted MBDA score (P = 0.025) or the original MBDA score (0.027), whereas the opposite was not true. CONCLUSION: Leptin-adjusted MBDA score significantly adds information to DAS28-CRP and the original MBDA score in predicting radiographic progression. It may offer improved clinical utility for personalized management of RA.

Persistence of tumor necrosis factor inhibitor or conventional synthetic disease-modifying antirheumatic drug monotherapy or combination therapy in psoriatic arthritis in a real-world setting.

This study described treatment patterns in a psoriatic arthritis (PsA) patient registry for new or ongoing tumor necrosis factor inhibitor (TNFi) monotherapy, conventional synthetic disease-modifying antirheumatic drug (csDMARD) monotherapy, or TNFi/csDMARD combination therapy. This retrospective analysis included adults with PsA who enrolled in the Corrona PsA/spondyloarthritis registry between March 21, 2013 (registry initiation), and January 31, 2017, and received an approved TNFi and/or csDMARD as "existing use" starting before registry entry or "initiated use" starting on/after registry entry. Therapy persistence was defined as index therapy use for ≥ 12 months without a treatment gap of ≥ 30 days. Among the evaluable patients with existing TNFi monotherapy (n = 251), csDMARD monotherapy (n = 225), and combination therapy (n = 214), 93, 87, and 87% were persistent for ≥ 12 months, and another 6, 5, and 5%, respectively, had no change with < 12 months of follow-up after first use. Among evaluable patients who initiated use of TNFi monotherapy (n = 26), csDMARD monotherapy (n = 35), and combination therapy (n = 15), 50, 43, and 53% were persistent for ≥ 12 months, and another 27, 20, and 20%, respectively, had no change with < 12 months of follow-up after first use. After initiation of index therapy, most changes (19-27% of patients) were discontinuation; 4-13% switched biologic therapy during follow-up. The results of this analysis of real-world treatment patterns in a PsA patient registry suggest that nonpersistence for TNFi monotherapy, csDMARD monotherapy, or TNFi/csDMARD combination therapy occurs more commonly after initiation of therapy than in patients with existing therapy. Trial registration: NCT02530268.

Sex differences in gout characteristics: tailoring care for women and men.

BACKGROUND: To characterize the differences between women and men with gout. METHODS: We analyzed a US national cohort of gout patients cared for by rheumatologists. RESULTS: Compared with the 1012 men with gout, women with gout (n = 262) were older (71 vs. 61 years, p < 0.001) and had a greater burden of comorbid conditions (p < 0.001 for hypertension, diabetes, renal disease and obesity). Risk factors for gout differed with women more often taking diuretics (p < 0.001), while men more frequently had dietary triggers (p < 0.05). CONCLUSIONS: The profiles of women and men with gout are markedly different, suggesting a need to tailor treatment recommendations.

Discontinuation of tumour necrosis factor inhibitors in patients with rheumatoid arthritis in low-disease activity: persistent benefits. Data from the Corrona registry.

BACKGROUND: There is increasing interest in discontinuing biological therapies for patients with rheumatoid arthritis (RA) achieving good clinical responses, provided patients maintain clinical benefit. METHODS: We assessed patients with RA from the Corrona registry who discontinued treatment with their first tumour necrosis factor inhibitor (TNFi) while in low-disease activity (LDA) or lower levels of disease activity. Patients were followed until they lost clinical benefit, defined as increased disease activity or change in RA medications. Duration of maintenance of clinical benefit was estimated using the Kaplan-Meier method. Cox proportional hazard models were assessed to identify factors related to maintenance of benefit. RESULTS: We identified 717 eligible patients with RA from 35,656 in the Corrona registry. At discontinuation, patients had a median RA duration of 8 years, mean clinical disease activity score of 4.3±0.11; 41.8% were using TNFi as monotherapy. 73.4% of patients maintained benefit for >12 months after discontinuing therapy and 42.2% did so through 24 months. Factors predictive of maintaining clinical benefit in multivariate analysis included lower disease activity, less pain and better functional status at the time of TNFi discontinuation. Among 301 patients initiating their first TNFi within the registry, faster responders (ie, those who achieved LDA in 4 months or less) did better than slower responders (HR 1.54 (95% CI 1.17 to 2.04)). RA disease duration did not affect maintenance of clinical benefit. CONCLUSIONS: Discontinuation of a first course of TNFi may be associated with persistent clinical benefit. Half of patients maintained response through 20 months. Several patient characteristics may help predict persistent benefit.

Genetic variation in the PNPLA3 gene and hepatocellular carcinoma in USA: risk and prognosis prediction.

Nonalcoholic fatty liver disease (NAFLD) is an emerging epidemic with high prevalence in Western countries. Genome-wide association studies had reported that a variation in the patatin-like phospholipase domain containing 3 (PNPLA3) gene is associated with high susceptibility to NAFLD. However, the relationship between this variation and hepatocellular carcinoma (HCC) has not been well established. We investigated the impact of PNPLA3 genetic variation (rs738409: C>G) on HCC risk and prognosis in the United States by conducting a case-control study that included 257 newly diagnosed and pathologically confirmed Caucasian patients with HCC (cases) and 494 healthy controls. Multivariate logistics and Cox regression models were used to control for the confounding effects of HCC risk and prognostic factors. We observed higher risk of HCC for subjects with a homozygous GG genotype than for those with CC or CG genotypes, the adjusted odds ratio (OR) was 3.21 (95% confidence interval [CI], 1.68-6.41). We observed risk modification among individuals with diabetes mellitus (OR = 19.11; 95% CI, 5.13-71.20). The PNPLA3 GG genotype was significantly associated with underlying cirrhosis in HCC patients (OR = 2.48; 95% CI, 1.05-5.87). Moreover, GG allele represents an independent risk factor for death. The adjusted hazard ratio of the GG genotype was 2.11 (95% CI, 1.26-3.52) compared with CC and CG genotypes. PNPLA3 genetic variation (rs738409: C>G) may determine individual susceptibility to HCC development and poor prognosis. Further experimental investigations are necessary for thorough assessment of the hepatocarcinogenic role of PNPLA3.

Earlier age of onset of BRCA mutation-related cancers in subsequent generations.

BACKGROUND: Women who are diagnosed with a deleterious mutation in either breast cancer (BRCA) gene have a high risk of developing breast and ovarian cancers at young ages. In this study, the authors assessed age at diagnosis in 2 generations of families with known mutations to investigate for earlier onset in subsequent generations. METHODS: Of the 132 BRCA-positive women with breast cancer who participated in a high-risk protocol at The University of Texas MD Anderson Cancer Center (Gen 2), 106 women could be paired with a family member in the previous generation (Gen 1) who was diagnosed with a BRCA-related cancer (either breast cancer or ovarian cancer). Age at diagnosis, location of the mutation, and year of birth were recorded. A previously published parametric anticipation model was applied in these genetically predisposed families. RESULTS: The median age of cancer diagnosis was 42 years (range, 28-55 years) in Gen 2 and 48 years (range, 30-72 years) in Gen 1 (P < .001). [corrected]. In the parametric model, the estimated change in the expected age at onset for the entire cohort was 7.9 years (P < .0001). Statistically significant earlier ages at diagnosis also were observed within subgroups of BRCA1 and BRCA2 mutations, maternal inheritance, paternal inheritance, breast cancer only, and breast cancer-identified and ovarian cancer-identified families. CONCLUSIONS: Breast and ovarian cancers in BRCA mutation carriers appeared to be diagnosed at an earlier age in later generations. The authors concluded that patients who are younger at the onset of BRCA-related cancers should continue to be tracked to offer appropriate screening modalities at appropriate ages.

Variants in folate pathway genes as modulators of genetic instability and lung cancer risk.

Genetic instability plays a crucial role in cancer development. The genetic stability of the cell as well as DNA methylation status could be modulated by folate levels. Several studies suggested associations between polymorphisms in folate genes and alterations in protein expression and variations in serum levels of the folate. The objective of this study was to investigate the effect of folate pathway polymorphisms on modulating genetic instability and lung cancer risk. Genotyping of 5 SNPs in folate pathway genes and cytokinesis-blocked micronucleus cytome assay analysis (to determine the genetic instability at baseline and following NNK treatment) was conducted on 180 lung cancer cases and 180 age-, gender-, and smoking-matched controls. Our results showed that individually, folate pathway SNPs were not associated with cytogenetic damage or lung cancer risk. However, in a polygenic disease such as lung cancer, gene-gene interactions are expected to play an important role in determining the phenotypic variability of the diseases. We observed that interactions between MTHFR677, MTHFR1298, and SHMT polymorphisms may have a significant impact on genetic instability in lung cancer patients. With regard to cytogenetic alterations, our results showed that lymphocytes from lung cancer patients exposed to the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone [NNK] had considerably increased frequency of cytogenetic damage in presence of MTHFR 677, MTHFR 1298, and SHMT allelic variants. These findings support the notion that significant interactions may potentially modulate the lung cancer susceptibility and alter the overall the repair abilities of lung cancer patients when exposed to tobacco carcinogens such as NNK.

Post-switch Effectiveness of Etanercept Biosimilar Versus Continued Etanercept in Rheumatoid Arthritis Patients with Stable Disease: A Prospective Multinational Observational Study.

INTRODUCTION: To better inform clinicians about the use of etanercept biosimilar (SB4) in patients with rheumatoid arthritis (RA), COMPANION-B, a prospective real-world observational study, evaluated the effectiveness of the voluntary switch from originator (etanercept, ETN) to SB4 in patients with stable RA (low-disease activity/remission). METHODS: The study recruited adult patients (18 years or older) with RA (2010 American College of Rheumatology criteria) prescribed ETN as their first or second biologic for at least 6 months across 14 sites in Canada and five in Australia. Patients had stable disease (Disease Activity Score-28 using erythrocyte sedimentation rate [DAS28-ESR] less than 3.2) at enrollment with no evidence of flare within the previous 3 months. Concomitant disease-modifying antirheumatic drugs (DMARDs) were permitted. Patients could elect to continue ETN or voluntarily switch to SB4 in consultation with their doctors. The primary effectiveness measure was the proportion of patients with disease worsening (defined as a DAS28-ESR increase of at least 1.2 from baseline and minimum score of at least 3.2 or a defined modification in RA treatment) during 12 months of follow-up. The secondary effectiveness measure was the proportion of patients with disease worsening at month 6. Serious adverse events (SAEs) and non-serious adverse reactions (NSARs) were recorded. RESULTS: Of 163 patients enrolled, 109 elected to continue on ETN and 54 switched to SB4; 65.8% of patients received non-biologic DMARD(s), 52.6% methotrexate, and 10.5% oral corticosteroid(s). At month 12, the proportion of patients with disease worsening was comparable in the ETN group (22.8% [95% CI 15.0-32.2]) and SB4 group (17.6% [95% CI 8.4-30.9]). Similarly, the proportions of patients with disease worsening were also comparable at month 6 (ETN: 7.9% [95% CI 3.5-15.0]; SB4: 7.8% [95% CI 2.2-18.9]). SAEs were low and similar across both groups (ETN: 8.7%; SB4: 5.7%). NSARs were slightly higher in the SB4 vs. ETN group (13.2% vs. 2.9%). CONCLUSIONS: SB4 demonstrated comparable effectiveness to ETN over 12 months in patients with stable RA who voluntarily switched to the biosimilar in a real-world setting.

Hodgkin lymphoma risk: role of genetic polymorphisms and gene-gene interactions in DNA repair pathways.

DNA repair variants may play a potentially important role in an individual's susceptibility to developing cancer. Numerous studies have reported the association between genetic single nucleotide polymorphisms (SNPs) in DNA repair genes and different types of hematologic cancers. However, to date, the effects of such SNPs on modulating Hodgkin lymphoma (HL) risk have not yet been investigated. We hypothesized that gene-gene interaction between candidate genes in direct reversal, nucleotide excision repair (NER), base excision repair (BER) and double strand break (DSB) pathways may contribute to susceptibility to HL. To test this hypothesis, we conducted a study on 200 HL cases and 220 controls to assess associations between HL risk and 21 functional SNPs in DNA repair genes. We evaluated potential gene-gene interactions and the association of multiple polymorphisms in a chromosome region using a multi-analytic strategy combining logistic regression, multi-factor dimensionality reduction and classification and regression tree approaches. We observed that, in combination, allelic variants in the XPC Ala499Val, NBN Glu185Gln, XRCC3 Thr241Me, XRCC1 Arg194Trp, and XRCC1 399Gln polymorphisms modify the risk for developing HL. Moreover, the cumulative genetic risk score revealed a significant trend where the risk for developing HL increases as the number of adverse alleles in BER and DSB genes increase. These findings suggest that DNA repair variants in BER and DSB pathways may play an important role in the development of HL.

Hodgkin disease risk: role of genetic polymorphisms and gene-gene interactions in inflammation pathway genes.

Inflammation is a critical component of cancer development. The clinical and pathological features of Hodgkin disease (HD) reflect an abnormal immunity that results from cytokines secreted by Reed-Sternberg cells and the surrounding tumor. Numerous studies have reported the association between genetic polymorphisms in cytokine genes and the susceptibility to different hematologic cancers. However, the effects of such SNPs on modulating HD risk have not yet been investigated. We hypothesized that gene-gene interactions between candidate genes in the anti- and pro-inflammatory pathways carrying suspicious polymorphisms may contribute to susceptibility to HD. To test this hypothesis, we conducted a study on 200 HD cases and 220 controls to assess associations between HD risk and 38 functional SNPs in inflammatory genes. We evaluated potential gene-gene interactions using a multi-analytic strategy combining logistic regression, multi-factor dimensionality reduction, and classification and regression tree (CART) approaches. We observed that, in combination, allelic variants in the COX2, IL18, ILR4, and IL10 genes modify the risk for developing HD. Moreover, the cumulative genetic risk score (CGRS) revealed a significant trend where the risk for developing HD increases as the number of adverse alleles in the cytokine genes increase. These findings support the notion that epigenetic-interactions between these cytokines may influence pathogenesis of HD modulating the proliferation of regulatory T cells. In this way, the innate and adaptative immune responses may be altered and defy their usual functions in the host anti-tumor response. Our study is the first to report the association between polymorphisms in inflammation genes and HD susceptibility risk.

Cytokinesis-blocked micronucleus assay and cancer risk assessment.

Cancer risk assessment is a multidisciplinary process that goes beyond the scope of classical epidemiology to include the biological evaluation of individual differences to carcinogenic exposures. The inclusion of genetic biomarkers such as mutagen sensitivity or cytokinesis-blocked micronucleus (CBMN) assay end points into risk assessment models allows for a more comprehensive determination of cancer risk that includes known demographic (age and gender), lifestyle exposures (smoking and alcohol) and occupational or environmental exposures. The CBMN assay generates multiple correlated end points that, after applying data reduction methods, could be combined into a summary measure that incorporates information from each individual variable into a single (or possible multiple, uncorrelated) measure of risk. In this article, we highlight the use of the CBMN assay in radiosensitivity assessment. In addition, we demonstrate the potential use of the combined summary measures in cancer risk assessment as a result of chronic exposure to tobacco carcinogens. The simplicity, rapidity and sensitivity of the CBMN assay not only make it a valuable tool for screening but also the multiple end points simultaneously generated lead to a better understanding of the underlying mechanisms involved in the carcinogenic process that could in turn substantially improve risk predictions.

Folate pathway polymorphisms predict deficits in attention and processing speed after childhood leukemia therapy.

BACKGROUND: Neurocognitive impairment occurs in 20-40% of childhood acute lymphoblastic leukemia (ALL) survivors, possibly mediated by folate depletion and homocysteine elevation following methotrexate treatment. We evaluated the relationship between folate pathway polymorphisms and neurocognitive impairment after childhood ALL chemotherapy. PROCEDURE: Seventy-two childhood ALL survivors treated with chemotherapy alone underwent a neurocognitive battery consisting of: Trail Making Tests A (TMTA) and B (TMTB), Grooved Pegboard Test Dominant-Hand and Nondominant-Hand, Digit Span subtest, and Verbal Fluency Test. We performed genotyping for: 10-methylenetetrahydrofolate reductase (MTHFR 677C>T and MTHFR 1298A>C), serine hydroxymethyltransferase (SHMT 1420C>T), methionine synthase (MS 2756 A>G), methionine synthase reductase (MTRR 66A>G), and thymidylate synthase (TSER). Student's two sample t-test and analysis of covariance were used to compare test scores by genotype. RESULTS: General impairment on the neurocognitive battery was related to MTHFR 1298A>C (P = 0.03) and MS 2756A>G (P = 0.05). Specifically, survivors with MTHFR 1298AC/CC genotypes scored, on average, 13 points lower on TMTB than those with MTHFR 1298AA genotype (P = 0.001). The MS 2756AA genotype was associated with a 12.2 point lower mean TMTA score, compared to MS 2756 AG/GG genotypes (P = 0.01). The TSER 2R/3R and 3R/3R genotypes were associated with an 11.4 point lower mean score on TMTB, compared to the TSER 2R/2R genotype (P = 0.03). Survivors with ≥6 folate pathway risk alleles demonstrated a 9.5 point lower mean TMTA score (P = 0.06) and 14.5 point lower TMTB score (P = 0.002) than survivors with <6 risk alleles. CONCLUSIONS: Folate pathway polymorphisms are associated with deficits in attention and processing speed after childhood ALL therapy.

Estimating individual risk for lung cancer.

Lung cancer risk prediction models hold the promise of improving patient care and streamlining research. The ultimate goal of these models is to inform clinicians as to which interventions their individual patients should receive to reduce lung cancer-associated morbidity and mortality. In this paper, we discuss the history and current state of lung cancer prediction models, focusing on three models: the Bach model, the Spitz model, and the Liverpool Lung Project (LLP) model. We also discuss the prospects for further development of improved prediction models for lung cancer risk. Although current models can identify those smokers at highest risk for lung cancer, these models are presently of limited use in the clinical setting. Nevertheless, lung cancer risk prediction models can be used during study enrollment to select more appropriate study subjects, and may eventually be useful in identifying patients for lung cancer screening or to receive chemoprevention.

Evaluation of Changes in Skin and Joint Outcomes and Associated Treatment Changes in Psoriatic Arthritis (PsA): Experience From the Corrona PsA/SpA Registry.

OBJECTIVE: To characterize skin severity and joint activity outcomes and associated treatment changes in patients with psoriatic arthritis (PsA) through 12 months of follow-up after enrollment in the Corrona Psoriatic Arthritis/Spondyloarthritis (PsA/SpA) Registry. METHODS: Patients ≥ 18 years of age with a diagnosis of PsA and a history of psoriasis between March 21, 2013, and September 30, 2016, were enrolled (n = 647). Demographics, clinical features, and treatment characteristics were collected and stratified by skin severity and joint activity. Change in joint and skin from enrollment to the 12-month visit was classified by change in category of Clinical Disease Activity Index (CDAI) or body surface area (BSA). Tests of association evaluated the relationship between changes in therapy and changes in skin severity and joint activity. RESULTS: Patients with improvement in both joint activity and skin severity saw the largest median reduction in both CDAI and BSA, while those who worsened in both had the greatest median increase in both CDAI and BSA. The majority of PsA patients (> 50%) had no change in skin severity regardless if they had reduced therapy (50%), no therapy changes (54%), or increased therapy (56%; P = 0.5875). However, there was a significant association between changes in therapy and changes in joint activity (P < 0.001). Patients who increased therapy were more likely to have improvement in joint activity (32%) compared to patients who reduced therapy (22%) or had no therapy changes (11%). CONCLUSION: The clinical implication for our findings suggests the assessment and incorporation of both skin and joint components may be advisable.

Gamma-radiation sensitivity and polymorphisms in RAD51L1 modulate glioma risk.

BACKGROUND: DNA strand breaks pose the greatest threat to genomic stability. Genetically determined mutagen sensitivity predisposes individuals to a variety of cancers, including glioma. However, polymorphisms in DNA strand break repair genes that may determine mutagen sensitivity are not well studied in cancer risk, especially in gliomas. METHODS: We correlated genotype data for tag single-nucleotide polymorphisms (tSNPs) of DNA strand break repair genes with a gamma-radiation-induced mutagen sensitivity phenotype [expressed as mean breaks per cell (B/C)] in samples from 426 glioma patients. We also conducted analysis to assess joint and haplotype effects of single-nucleotide polymorphisms (SNPs) on mutagen sensitivity. We further validate our results in an independent external control group totaling 662 subjects. RESULTS: Of the 392 tSNPs examined, we found that mutagen sensitivity was modified by one tSNP in the EME2 gene and six tSNPs in the RAD51L1 gene (P < 0.01). Among the six RAD51L1 SNPs tested in the validation set, one (RAD51L1 rs2180611) was significantly associated with mutagen sensitivity (P = 0.025). Moreover, we found a significant dose-response relationship between the mutagen sensitivity and the number of adverse tSNP genotypes. Furthermore, haplotype analysis revealed that RAD51L1 haplotypes F-A (zero adverse allele) and F-E (six adverse alleles) exhibited the lowest (0.42) and highest (0.93) mean B/C values, respectively. A similar dose-response relationship also existed between the mutagen sensitivity and the number of adverse haplotypes. CONCLUSION: These results suggest that polymorphisms in and haplotypes of the RAD51L1 gene, which is involved in the double-strand break repair pathway, modulate gamma-radiation-induced mutagen sensitivity.

Pooling dietary data using questionnaires with open-ended and predefined responses: implications for comparing mean intake or estimating odds ratios.

In the current era of diet-gene analyses, large sample sizes are required to uncover the etiology of complex diseases. As such, consortia form and often combine available data. Food frequency questionnaires, which commonly use 2 different types of responses about the frequency of intake (predefined responses and open-ended responses), may be pooled to achieve the desired sample size. The common practice is to categorize open-ended responses into the predefined response categories. A problem arises when the predefined categories are noncontiguous: possible open-ended responses may fall in gaps between the predefined categories. Using simulated data modeled from frequency of intake among 1,664 controls in a lung cancer case-control study at The University of Texas M. D. Anderson Cancer Center (Houston, Texas, 2000-2005), the authors describe the effect of different categories of open-ended responses that fall in between noncontiguous, predefined response sets on estimates of the mean difference in intake and the odds ratios. A significant inflation of false positives appears when comparing mean differences of intake, while the bias in estimating odds ratios may be acceptably small. Therefore, if pooling data cannot be restricted to the same type of response, inferences should focus on odds ratio estimation to minimize bias.