Genetic modifiers of radon-induced lung cancer risk: a genome-wide interaction study in former uranium miners.

PURPOSE: Radon is a risk factor for lung cancer and uranium miners are more exposed than the general population. A genome-wide interaction analysis was carried out to identify genomic loci, genes or gene sets that modify the susceptibility to lung cancer given occupational exposure to the radioactive gas radon. METHODS: Samples from 28 studies provided by the International Lung Cancer Consortium were pooled with samples of former uranium miners collected by the German Federal Office of Radiation Protection. In total, 15,077 cases and 13,522 controls, all of European ancestries, comprising 463 uranium miners were compared. The DNA of all participants was genotyped with the OncoArray. We fitted single-marker and in multi-marker models and performed an exploratory gene-set analysis to detect cumulative enrichment of significance in sets of genes. RESULTS: We discovered a genome-wide significant interaction of the marker rs12440014 within the gene CHRNB4 (OR = 0.26, 95% CI 0.11-0.60, p = 0.0386 corrected for multiple testing). At least suggestive significant interaction of linkage disequilibrium blocks was observed at the chromosomal regions 18q21.23 (p = 1.2 × 10-6), 5q23.2 (p = 2.5 × 10-6), 1q21.3 (p = 3.2 × 10-6), 10p13 (p = 1.3 × 10-5) and 12p12.1 (p = 7.1 × 10-5). Genes belonging to the Gene Ontology term "DNA dealkylation involved in DNA repair" (GO:0006307; p = 0.0139) or the gene family HGNC:476 "microRNAs" (p = 0.0159) were enriched with LD-blockwise significance. CONCLUSION: The well-established association of the genomic region 15q25 to lung cancer might be influenced by exposure to radon among uranium miners. Furthermore, lung cancer susceptibility is related to the functional capability of DNA damage signaling via ubiquitination processes and repair of radiation-induced double-strand breaks by the single-strand annealing mechanism.

Two-locus approach of segregation and linkage analysis in the study of complex traits.

A two-locus segregation and linkage-analysis approach was used to characterize the genetic control of a complex trait (Q1) and to localize the genes that have detectable effects. The results suggested that a two-locus Mendelian model fit the data significantly better than a one-locus model. The linkage results based on the most parsimonious two-locus model revealed linkage of Q1 to two areas (MG2 and MG3), while there was less evidence for linkage using one-locus models. Results also suggested that the subphenotypes (Q2 and Q3) provided useful information for further analysis of Q1 using two-locus models.

Drug survival, efficacy and toxicity of monotherapy with a fully human anti-tumour necrosis factor-alpha antibody compared with methotrexate in long-standing rheumatoid arthritis.

OBJECTIVES: To compare the 48-week drug survival, efficacy and toxicity of monotherapy with a fully human anti-tumour necrosis factor-alpha (TNF-alpha) monoclonal antibody (moAb) and methotrexate (MTX) in patients with active long-standing rheumatoid arthritis (RA). Secondary aims were to identify potential predictors for clinical response. METHODS: Patients with RA, enrolled in phase I trials with a human anti-TNF-alpha moAb and followed for at least 48 weeks at our centre, were compared with patients receiving MTX monotherapy without folate supplementation. The first 6 weeks of anti-TNF therapy were placebo-controlled and followed by an open-label study. Patients treated with MTX participated in a 48-week, double-blind, phase III study of MTX alone vs MTX with folate supplementation, which was co-ordinated by our department. The studies with anti-TNF-alpha and MTX were performed in the same period and had very similar inclusion, exclusion, response and stop criteria. RESULTS: Sixty-one patients treated with anti-TNF-alpha moAb were compared with 137 receiving MTX monotherapy. At baseline, patients in the anti-TNF-alpha group had a longer disease duration (median 108 vs 50 months, P=0.0001) and a more protracted history of second-line anti-rheumatic drugs than those treated with MTX (median 4 vs 1, P=0.0001). The 48-week dropout rate was lower among patients treated with anti-TNF (23 vs 45% in the MTX group, P<0.005). Proportional hazard analysis showed a significantly lower dropout risk among anti-TNF-treated patients [relative risk (95% confidence interval): 0.28 (0.12-0.6) uncorrected and 0.17 (0.06-0.45) corrected for confounders). The 48-week area under the curve for the disease activity score (DAS) was smaller in the anti-TNF-alpha group than in the MTX group (P=0.005). The percentage of responders was higher in the anti-TNF-alpha group over the whole study period. The median percentage of visits in which a patient fulfilled the European League Against Rheumatism (EULAR) response criteria was 83% in the anti-TNF-alpha group vs 40% in the MTX group (P=0.0001). Clinical and demographic characteristics were, in general, poor predictors for response to therapy at week 48. The clinical response after the first anti-TNF-alpha dose tended to increase the chance of prolonged efficacy of this approach [relative risk (95% confidence interval): 2 (0.75-6.0)]. The previous number of second-line drugs was the only predictive variable for response to MTX to which it was inversely related [relative risk (95% confidence interval): -0.71 (-0.57 to -0.88)]. CONCLUSIONS: In patients with active, long-standing RA, blocking TNF-alpha is more effective and better tolerated than MTX monotherapy. An early response increases the chance of a sustained effect of anti-TNF-alpha. In contrast to MTX, the response to anti-TNF-alpha is not affected by previous disease-modifying anti-rheumatic drug history.