| 1. |
- Burgess, S., et al.
(author)
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Bayesian methods for meta-analysis of causal relationships estimated using genetic instrumental variables
- 2010
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In: Statistics in medicine. - : Wiley. - 1097-0258 .- 0277-6715. ; 29:12, s. 1298-311
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Journal article (peer-reviewed)abstract
- Genetic markers can be used as instrumental variables, in an analogous way to randomization in a clinical trial, to estimate the causal relationship between a phenotype and an outcome variable. Our purpose is to extend the existing methods for such Mendelian randomization studies to the context of multiple genetic markers measured in multiple studies, based on the analysis of individual participant data. First, for a single genetic marker in one study, we show that the usual ratio of coefficients approach can be reformulated as a regression with heterogeneous error in the explanatory variable. This can be implemented using a Bayesian approach, which is next extended to include multiple genetic markers. We then propose a hierarchical model for undertaking a meta-analysis of multiple studies, in which it is not necessary that the same genetic markers are measured in each study. This provides an overall estimate of the causal relationship between the phenotype and the outcome, and an assessment of its heterogeneity across studies. As an example, we estimate the causal relationship of blood concentrations of C-reactive protein on fibrinogen levels using data from 11 studies. These methods provide a flexible framework for efficient estimation of causal relationships derived from multiple studies. Issues discussed include weak instrument bias, analysis of binary outcome data such as disease risk, missing genetic data, and the use of haplotypes.
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| 2. |
- Chen, Tianhui, et al.
(author)
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IGF-I during primiparous pregnancy and maternal risk of breast cancer
- 2010
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In: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 0167-6806 .- 1573-7217. ; 121:1, s. 169-175
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Journal article (peer-reviewed)abstract
- Previously, we reported that insulin-like growth factor (IGF)-I during early pregnancy is positively associated with maternal risk of breast cancer. To further explore this association, we designed a new study limited to women who donated a blood sample during their first pregnancy ending with childbirth. A case-control study was nested within the Northern Sweden Maternity Cohort in which repository since 1975, serum specimens remaining after early pregnancy screening for infectious diseases had been preserved. Study subjects were selected among women who donated a blood sample during the full-term pregnancy that led to the birth of their first child. Two hundred and forty-four women with invasive breast cancer were eligible. Two controls, matching the index case for age and date at blood donation were selected (n = 453). IGF-I was measured in serum samples on an Immulite 2000 analyzer. Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals. A significant positive association of breast cancer with IGF-I was observed, with OR of 1.73 (95% CI: 1.14-2.63) for the top tertile, P < 0.009. Subgroup analyses did not indicate statistical heterogeneity of the association by ages at sampling and diagnosis or by lag time to cancer diagnosis, although somewhat stronger associations with risk were observed in women < or = age 25 at index pregnancy and for cases diagnosed within 15 years of blood donation. The results of the study add further evidence for an adverse effect of elevated IGF-I concentrations during early reproductive life on risk of breast cancer.
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| 3. |
- Chen, Tianhui, et al.
(author)
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Maternal hormones during early pregnancy : a cross-sectional study
- 2010
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In: Cancer Causes and Control. - : Springer Science and Business Media LLC. - 0957-5243 .- 1573-7225. ; 21:5, s. 719-727
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Journal article (peer-reviewed)abstract
- BACKGROUND: Little is known about correlates of first-trimester pregnancy hormones as in most studies maternal hormones have been measured later in gestation. We examined the associations of maternal characteristics and child sex with first-trimester maternal concentrations of four hormones implicated in breast cancer: human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP), insulin-like growth factor (IGF)-I, and IGF-II. METHODS: About 338 serum samples donated to the Northern Sweden Maternity Cohort (NSMC), 1975-2001, during the first trimester of uncomplicated pregnancies, were analyzed for the hormones of interest as a part of a case-control study. The associations of maternal characteristics and child sex with hormone concentrations were investigated by correlation, general linear regression, and multivariate regression models. RESULTS: In the first trimester, greater maternal age was inversely correlated with IGF-I and IGF-II. In comparison with women carrying their first child, already parous women had higher IGF-I but lower hCG. Greater maternal weight and smoking were inversely correlated with hCG. No differences in hormone levels by child sex were observed. CONCLUSIONS: Our analyses indicated that potentially modifiable maternal characteristics (maternal weight and smoking) influence first-trimester pregnancy maternal hormone concentrations.
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| 4. |
- Duell, Eric J., et al.
(author)
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Genetic variation in alcohol dehydrogenase (ADH1A, ADH1B, ADH1C, ADH7) and aldehyde dehydrogenase (ALDH2), alcohol consumption and gastric cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort
- 2012
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In: Carcinogenesis. - Oxford : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 33:2, s. 361-367
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Journal article (peer-reviewed)abstract
- Studies that have examined the association between alcohol consumption and gastric cancer (GC) risk have been inconsistent. We conducted an investigation of 29 genetic variants in alcohol metabolism loci (alcohol dehydrogenase, ADH1 gene cluster: ADH1A, ADH1B and ADH1C; ADH7 and aldehyde dehydrogenase, ALDH2), alcohol intake and GC risk. We analyzed data from a nested case-control study (364 cases and 1272 controls) within the European Prospective Investigation into Cancer and Nutrition cohort. Single nucleotide polymorphisms (SNPs) were genotyped using a customized array. We observed a statistically significant association between a common 3'-flanking SNP near ADH1A (rs1230025) and GC risk [allelic odds ratio (OR)(A v T) = 1.30, 95% confidence interval (CI) = 1.07-1.59]. Two intronic variants, one in ADH1C (rs283411) and one in ALDH2 (rs16941667), also were associated with GC risk (ORT v C = 0.59; 95% CI = 0.38-0.91 and ORT v C = 1.34; 95% CI = 1.00-1.79, respectively). Individuals carrying variant alleles at both ADH1 (rs1230025) and ALDH2 (rs16941667) were twice as likely to develop GC (ORA+T = 2.0; 95% CI = 1.25-3.20) as those not carrying variant alleles. The association between rs1230025 and GC was modified by alcohol intake (< 5 g/day: ORA = 0.89, 95% CI = 0.57-1.39; >= 5 g/day: ORA = 1.45, 95% CI = 1.08-1.94, P-value = 0.05). The association was also modified by ethanol intake from beer. A known functional SNP in ADH1B (rs1229984) was associated with alcohol intake (P-value = 0.04) but not GC risk. Variants in ADH7 were not associated with alcohol intake or GC risk. In conclusion, genetic variants at ADH1 and ALDH2 loci may influence GC risk, and alcohol intake may further modify the effect of ADH1 rs1230025. Additional population-based studies are needed to confirm our results.
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| 5. |
- Eriksson, Catharina, 1955-, et al.
(author)
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Autoantibodies predate the onset of Systemic Lupus Erythematosus in northern Sweden
- 2011
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In: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6354 .- 1478-6362. ; 13:1, s. R30-
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Journal article (peer-reviewed)abstract
- INTRODUCTION: Autoantibodies have a central role in systemic lupus erythematosus (SLE). The presence of autoantibodies preceding disease onset by years has been reported both in patients with SLE and those with rheumatoid arthritis, suggesting a gradual development of these diseases. To identify autoantibodies in a Northern European population predating the onset of symptoms of SLE and their relationship to presenting symptoms.METHODS: The register of patients fulfilling the American College of Rheumatology (ACR) criteria for SLE and with a given date for the onset of symptoms was co-analysed with the register of the Medical Biobank, Umea, Sweden. Thirty-eight patients were identified as having donated blood samples prior to symptom onset. A nested case-control study (1:4) was performed with 152 age- and sex-matched controls identified from within the Biobank register. Antibodies against anti- Sjogren's syndrome antigen A (Ro/SSA) (60 and 52 kDa), anti- Sjogren's syndrome antigen B (La/SSB), anti-Smith antibody (Sm), ribonucleoprotein (RNP), scleroderma-70 (Scl-70), anti- histidyl-tRNA synthetase antibody (Jo-1), double-stranded DNA (dsDNA); Centromere protein B and histones were analysed using the anti-nuclear antibody test II (ANA-II) Plus Test System (Athena Multi-Lyte(R)) on a Bio-Plex Array Reader (Luminex200). ANA were analysed using indirect immunofluorescence on Human Epidermal cells-2 (HEp2-cells) at a sample dilution of 1:100.RESULTS: Autoantibodies against nuclear antigens were detected 5.6 (+/- 4.7; mean +/- SD) years before the onset of symptoms and 8.7 (+/- 5.6) years before diagnosis in 63% of the individuals who subsequently developed SLE. The sensitivity (45.7%) was highest for ANA with a specificity of 95%, followed by anti-dsDNA and anti-Ro/SSA antibodies both with sensitivities of 20.0% at specificities of 98.7% and 97.4%, respectively. The odds ratio (OR) for anti-dsDNA predicting disease was 18.13 (CI 95%; 3.58-91.84), and for ANA 11.5 (CI 95%; 4.54-28.87). Anti-Ro/SSA antibodies appeared first, 6.6 (+/- 2.5) years prior to symptom onset. The mean number of autoantibodies in pre-diseased individuals was 1.4 and after disease onset 3.1 (P< 0.0005). The time predating disease was shorter, and the number of autoantibodies greater, in those individuals with serositis as a presenting symptom in comparison to those with arthritis and skin manifestations.CONCLUSIONS: Autoantibodies against nuclear antigens were detected in individuals developing SLE several years before the onset of symptoms and diagnosis. The most sensitive autoantibodies were ANA, Ro/SSA and dsDNA, with the highest predictive OR for anti-dsDNA antibodies. The first autoantibodies detected were anti-Ro/SSA.
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| 6. |
- Kokkonen, Heidi, et al.
(author)
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Antibodies of IgG, IgA and IgM isotypes against cyclic citrullinated peptide precede the development of rheumatoid arthritis
- 2011
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In: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6354 .- 1478-6362. ; 13:1, s. R13-
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Journal article (peer-reviewed)abstract
- INTRODUCTION: We and others have previously shown that antibodies against cyclic citrullinated proteins (anti-CCP) precede the development of rheumatoid arthritis (RA) and in a more recent study we reported that individuals who subsequently developed RA had increased concentrations of several cytokines and chemokines years before the onset of symptoms of joint disease. Here we aimed to evaluate the prevalence and predictive values of anti-CCP antibodies of IgG, IgM and IgA isotype in individuals who subsequently developed RA and also to relate these to cytokines and chemokines, smoking, genetic factors and radiographic score. METHODS: A case-control study (1:4 ratio) was nested within the Medical Biobank and the Maternity cohorts of Northern Sweden. Patients with RA were identified from blood donors predating the onset of disease by years. Matched controls were selected randomly from the same registers. IgG, IgA and IgM anti-CCP2 antibodies were determined using EliA anti-CCP assay on ImmunoCAP 250 (Phadia AB, Uppsala, Sweden). RESULTS: Of 86 patients with RA identified as blood donors prior to the onset of symptoms, samples were available from 71 for analyses. The median (Q1 to Q3) predating time was 2.5 years (1.1 to 5.9 years). The sensitivity of anti-CCP antibodies in the pre-patient samples was 35.2% for IgG, 23.9% for IgA, and 11.8% for IgM. The presence of IgG and IgA anti-CCP antibodies was highly significant compared with controls. IgG and IgA anti-CCP2 predicted RA significantly in conditional logistic regression models odds ratio (OR) = 94.1, 95% confidence interval (CI) 12.7 to 695.4 and OR = 11.1, 95% CI 4.4 to 28.1, respectively, the IgM anti-CCP showed borderline significance OR = 2.5 95% CI 0.9 to 6.3. Concentrations of all anti-CCP isotypes increased the closer to the onset of symptoms the samples were collected with an earlier and higher increase for IgG and IgA compared with IgM anti-CCP. IgA and IgG anti-CCP positive individuals had different patterns of up-regulated chemokines and also, smoking brought forward the appearance of IgA anti-CCP antibodies in pre-RA individuals. CONCLUSIONS: Anti-CCP2 antibodies of both the IgG and IgA isotypes pre-dated the onset of RA by years; also, both IgG and IgA anti-CCP2 antibodies predicted the development of RA, with the highest predictive value for IgG anti-CCP2 antibodies.
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| 7. |
- Kreimer, Aimée R, et al.
(author)
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Evaluation of human papillomavirus antibodies and risk of subsequent head and neck cancer
- 2013
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In: Journal of Clinical Oncology. - 0732-183X .- 1527-7755. ; 31:21, s. 2708-2715
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Journal article (peer-reviewed)abstract
- PURPOSE:Human papillomavirus type 16 (HPV16) infection is causing an increasing number of oropharyngeal cancers in the United States and Europe. The aim of our study was to investigate whether HPV antibodies are associated with head and neck cancer risk when measured in prediagnostic sera.METHODS:We identified 638 participants with incident head and neck cancers (patients; 180 oral cancers, 135 oropharynx cancers, and 247 hypopharynx/larynx cancers) and 300 patients with esophageal cancers as well as 1,599 comparable controls from within the European Prospective Investigation Into Cancer and Nutrition cohort. Prediagnostic plasma samples from patients (collected, on average, 6 years before diagnosis) and control participants were analyzed for antibodies against multiple proteins of HPV16 as well as HPV6, HPV11, HPV18, HPV31, HPV33, HPV45, and HPV52. Odds ratios (ORs) of cancer and 95% CIs were calculated, adjusting for potential confounders. All-cause mortality was evaluated among patients using Cox proportional hazards regression.RESULTS:HPV16 E6 seropositivity was present in prediagnostic samples for 34.8% of patients with oropharyngeal cancer and 0.6% of controls (OR, 274; 95% CI, 110 to 681) but was not associated with other cancer sites. The increased risk of oropharyngeal cancer among HPV16 E6 seropositive participants was independent of time between blood collection and diagnosis and was observed more than 10 years before diagnosis. The all-cause mortality ratio among patients with oropharyngeal cancer was 0.30 (95% CI, 0.13 to 0.67), for patients who were HPV16 E6 seropositive compared with seronegative.CONCLUSION:HPV16 E6 seropositivity was present more than 10 years before diagnosis of oropharyngeal cancers.
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| 8. |
- Manjer, Jonas, et al.
(author)
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Vitamins B2 and B6 and genetic polymorphisms related to one-carbon metabolism as risk factors for gastric adenocarcinoma in the European prospective investigation into cancer and nutrition.
- 2010
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In: Cancer Epidemiology, Biomarkers and Prevention. - 1055-9965 .- 1538-7755. ; 19:1, s. 28-38
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Journal article (peer-reviewed)abstract
- B vitamins and polymorphisms in genes coding for enzymes involved in one-carbon metabolism may affect DNA synthesis and methylation and thereby be implicated in carcinogenesis. Previous data on vitamins B2 and B6 and genetic polymorphisms other than those involving MTHFR as risk factors for gastric cancer (GC) are sparse and inconsistent. In this case-control study nested within the European Prospective Investigation into Cancer and Nutrition cohort, cases (n = 235) and controls (n = 601) were matched for study center, age, sex, and time of blood sampling. B2 and B6 species were measured in plasma, and the sum of riboflavin and flavin mononucleotide was used as the main exposure variable for vitamin B2 status, whereas the sum of pyridoxal 5'-phosphate, pyridoxal, and 4-pyridoxic acid was used to define vitamin B6 status. In addition, we determined eight polymorphisms related to one-carbon metabolism. Relative risks for GC risk were calculated with conditional logistic regression, adjusted for Helicobacter pylori infection status and smoking status. Adjusted relative risks per quartile (95% confidence interval, P(trend)) were 0.85 (0.72-1.01, 0.06) for vitamin B2 and 0.78 (0.65-0.93, <0.01) for vitamin B6. Both relations were stronger in individuals with severe chronic atrophic gastritis. The polymorphisms were not associated with GC risk and did not modify the observed vitamin-cancer associations. In summary, results from this large European cohort study showed an inverse association between vitamin B2 and GC risk, which is borderline significant, and a significant inverse association between vitamin B6 and GC risk.
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| 9. |
- Neasham, David, et al.
(author)
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Occupation and risk of lymphoma : a multicentre prospective cohort study (EPIC)
- 2011
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In: Occupational and Environmental Medicine. - : BMJ. - 1351-0711 .- 1470-7926. ; 68:1, s. 77-81
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Journal article (peer-reviewed)abstract
- The findings in this current study of a higher risk of NHL among car repair workers and butchers and a higher risk of HL among gasoline station workers suggest a possible role from occupationally related exposures, such as solvents and zoonotic viruses, as risk factors for malignant lymphoma.
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| 10. |
- Salzer, Jonatan, 1981-, et al.
(author)
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Epstein-Barr virus antibodies and vitamin D in prospective multiple sclerosis biobank sampels
- 2013
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In: Multiple Sclerosis Journal. - : Sage Publications. - 1352-4585 .- 1477-0970. ; 19:12, s. 1587-1591
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Journal article (peer-reviewed)abstract
- Background: Increased antibody reactivity against Epstein-Barr Nuclear Antigen-1 (EBNA-1) has been associated with an increased risk for MS, and high levels of 25-Hydroxyvitamin D (25[OH]D) have been associated with a lower risk for MS. Interaction between these two factors has been proposed.Objectives: To examine the association between antibody reactivity against EBNA-1 and five EBNA-1 domains, and the risk for multiple sclerosis (MS), and to examine if these antibodies and 25(OH)D status interact regarding MS risk in prospectively collected blood samples.Methods: Antibody reactivity (as specified above) and 25(OH)D levels were measured using ELISAs in n=192 MS cases and n=384 matched controls. The risk for MS was analysed using matched logistic regression.Results: The risk for MS increased across tertiles of antibody reactivity against EBNA-1, domain EBNA-1402–502, and domain EBNA-1385–420; p trend <0.001. The risk increase was most pronounced for EBNA-1385–420. In young individuals (below median age at sampling, <26.4 years) these associations were stronger, and 25(OH)D levels correlated inversely to antibody reactivity against EBNA-1 and the EBNA-1 domains.Conclusions: We confirm that increased antibody reactivity against EBNA-1 is a risk factor for MS. Our findings in young individuals suggest that 25(OH)D status might influence the immune response towards Epstein-Barr virus, and thereby modulate MS risk.
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