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  • 1
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  Kongress Medizin und Gesellschaft 2007; 20070917-20070921; Augsburg; DOC07gmds278 /20070906/
    Publication Date: 2007-09-07
    Keywords: ddc: 610
    Language: English
    Type: conferenceObject
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  • 2
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  Mainz//2011; 56. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie (gmds), 6. Jahrestagung der Deutschen Gesellschaft für Epidemiologie (DGEpi); 20110926-20110929; Mainz; DOC11gmds180 /20110920/
    Publication Date: 2011-09-20
    Keywords: Apolipoprotein A-IV ; cardiovascular disease ; all-cause mortality ; hemodialysis ; ddc: 610
    Language: English
    Type: conferenceObject
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  • 3
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    German Medical Science GMS Publishing House; Düsseldorf
    In:  Jahrestagung der Gesellschaft für Medizinische Ausbildung (GMA); 20140925-20140927; Hamburg; DOCP417 /20140911/
    Publication Date: 2014-09-12
    Keywords: ddc: 610
    Language: German
    Type: conferenceObject
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  • 4
    Keywords: RECEPTOR ; Germany ; MODEL ; MODELS ; SUPPORT ; COHORT ; DISEASE ; EPIDEMIOLOGY ; POPULATION ; RISK ; GENE ; SAMPLE ; SAMPLES ; ASSOCIATION ; polymorphism ; POLYMORPHISMS ; single nucleotide polymorphism ; score ; PHENOTYPES ; SUBUNIT ; genetics ; smoking ; REGION ; PHENOTYPE ; VARIANT ; DEPENDENCE ; SINGLE NUCLEOTIDE POLYMORPHISMS ; ADDICTION ; SINGLE-NUCLEOTIDE POLYMORPHISMS ; pharmacogenomics ; pharmacology ; smoking cessation ; EXTENT ; Polymorphism,Single Nucleotide ; GENERAL-POPULATION ; genetic association ; NICOTINE DEPENDENCE ; Genetic ; Determination ; CHRNA4 ; Fagerstrom score ; TOBACCO DEPENDENCE
    Abstract: Polymorphisms in the CHRNA4 gene coding the nicotinic acetylcholine receptor subunit alpha 4 have recently been suggested to play a role in the determination of smoking-related phenotypes. To examine this hypothesis, we conducted a genetic association study in three large samples from the German general population (N-1 = 1412; N-2 = 1855; N-3 = 2294). Five single-nucleotide polymorphisms in CHRNA4 were genotyped in 5561 participants, including 2707 heavily smoking cases (regularly smoking at least 20 cigarettes per day) and 2399 never-smoking controls (〈= 100 cigarettes over lifetime). We examined associations of the polymorphisms with smoking case-control status and with the extent of nicotine dependence as measured by the Fagerstrom test of nicotine dependence (FTND) score (N = 1030). The most significant association was observed between rs2236196 and FTND (P = 0.0023), whereas the closely linked rs1044396 had most statistical support in the case-control models (P = 0.0080). The consistent effect estimates across three independent cohorts elaborate on recently published functional studies of rs2236196 from the CHRNA4 3'-untranslated region and seem to converge with accumulating evidence to firmly implicate the variant G allele of this polymorphism in the intensification of nicotine dependence. The Pharmacogenomics Journal (2009) 9, 219-224; doi: 10.1038/tpj.2009.6; published online 17 March 2009
    Type of Publication: Journal article published
    PubMed ID: 19290018
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  • 5
    Keywords: CELLS ; EXPRESSION ; CELL ; COMBINATION ; Germany ; human ; COHORT ; POPULATION ; RISK ; GENE ; PROTEIN ; SAMPLE ; SAMPLES ; DNA ; BINDING ; ASSOCIATION ; polymorphism ; POLYMORPHISMS ; single nucleotide polymorphism ; VARIANTS ; HUMANS ; ASSAY ; PROMOTER ; SNP ; OBESITY ; SINGLE ; VARIANT ; SINGLE NUCLEOTIDE POLYMORPHISMS ; FUNCTIONAL-CHARACTERIZATION ; HAPLOTYPES ; INSULIN-RESISTANCE ; metabolic syndrome ; USA ; REPLACEMENT ; Adiponectin ; STATE ; Luciferase reporter ; PLASMA ADIPONECTIN ; TYPE-2 DIABETIC-PATIENTS ; APM1 GENE ; HYPOADIPONECTINEMIA
    Abstract: OBJECTIVE-Adiponectin (APM1, ACDC) is an adipocyte-derived protein with downregulated expression in obesity and insulin-resistant states. Several potentially regulatory single nucleotide polymorphisms (SNPs) within the APM1 gene promoter region have been associated with circulating adiponectin levels. None of them have been functionally characterized in adiponectin-expressing cells. Hence, we investigated three SNPs (rs16861194, rs17300539, and rs266729) for their influence on adiponectin promoter activity and their association with circulating adiponectin levels. RESEARCH DESIGN AND METHODS-Basal and rosiglitazone-induced promoter activity of different SNP combinations (haplotypes) was analyzed in 3T3-L1 adipocytes using luciferase reporter gene assays and DNA binding studies comparing all possible APM1 haplotypes. This functional approach was complemented with analysis of epidemiological population-based data of 1,692 participants of the MONICA/KORA S123 cohort and 696 participants from the KORA S4 cohort for SNP and haplotype association with circulating adiponectin levels. RESULTS-Major to minor allele replacements of the three SNPs revealed significant effects on promoter activity in luciferase assays. Particularly, a minor variant in rs16861194 resulted in reduced basal and rosiglitazone-induced promoter activity and hypoadiponectinemia in the epidemiological datasets. The haplotype with the minor allele in all three SNPs showed a complete loss of promoter activity, and no subject carried this haplotype in either of the epidemiological samples (combined P value for statistically significant difference from a random sample was 0.006). CONCLUSIONS-Our results clearly demonstrate that promoter variants associated with hypoadiponectinemia in humans substantially affect adiponectin promoter activity in adipocytes. Our combination of functional experiments with epidemiological data overcomes the drawback of each approach alone. Diabetes 58-984-991, 2009
    Type of Publication: Journal article published
    PubMed ID: 19074982
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  • 6
    Abstract: Genetic factors contribute to the overall risk of developing nicotine addiction, which is the major cause of preventable deaths in western countries. However, knowledge regarding specific polymorphisms influencing smoking phenotypes remains scarce. In the present study we provide evidence that a common single nucleotide polymorphism (SNP) in the 5' untranslated region of CHRM2, the gene coding for the muscarinic acetylcholine receptor 2 is associated with nicotine addiction. CHRM2 was defined as a candidate gene for nicotine addiction based on previous evidence that linked variations in CHRM2 to alcohol and drug dependence. A total of more than 5,500 subjects representative of the German population were genotyped and assessed regarding their smoking habits. The impact of three SNPs in CHRM2 on smoking behavior/nicotine addiction was investigated using logistic regression models or a quasi-Poisson regression model, respectively. We found the T allele of SNP rs324650 to be associated with an increased risk of smoking/nicotine dependence according to three different models, the recessive models of regular or heavy smokers vs. never-smokers (odds ratio 1.17 in both analyses) and according to the Fagerström index of nicotine addiction. In the analysis stratified by gender this association was only found in females. Our data provide further evidence that variations in CHRM2 may be associated with the genetic risk of addiction in general or with certain personality traits that predispose to the development of addiction. Alternatively, variations in CHRM2 could modulate presynaptic auto-regulation in cholinergic systems and may thereby affect an individual's response to nicotine more specifically. (c) 2009 Wiley-Liss, Inc.
    Type of Publication: Journal article published
    PubMed ID: 19644963
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  • 7
    Keywords: SIMULATIONS ; Germany ; POPULATION ; GENE ; SAMPLE ; IMPACT ; SIMULATION ; ASSOCIATION ; polymorphism ; single nucleotide polymorphism ; SUSCEPTIBILITY ; FREQUENCIES ; PERFORMANCE ; NUMBER ; genetics ; SNP ; GENOTYPES ; MEASUREMENT ERROR ; genotyping ; UNCERTAINTY ; sensitivity ; SNPs ; methods ; GENOTYPE ; HAPLOTYPE ; HAPLOTYPES ; TESTS ; TRAITS ; LINKAGE PHASE ; genetic association ; Genetic ; MISCLASSIFICATION ; PROBABILITIES ; single nucleotide ; association studies ; genotyping error
    Abstract: P〉Haplotypes are an important concept for genetic association studies, but involve uncertainty due to statistical reconstruction from single nucleotide polymorphism (SNP) genotypes and genotype error. We developed a re-sampling approach to quantify haplotype misclassification probabilities and implemented the MC-SIMEX approach to tackle this as a 3 x 3 misclassification problem. Using a previously published approach as a benchmark for comparison, we evaluated the performance of our approach by simulations and exemplified it on real data from 15 SNPs of the APM1 gene. Misclassification due to reconstruction error was small for most, but notable for some, especially rarer haplotypes. Genotype error added misclassification to all haplotypes resulting in a non-negligible drop in sensitivity. In our real data example, the bias of association estimates due to reconstruction error alone reached -48.2% for a 1% genotype error, indicating that haplotype misclassification should not be ignored if high genotype error can be expected. Our 3 x 3 misclassification view of haplotype error adds a novel perspective to currently used methods based on genotype intensities and expected number of haplotype copies. Our findings give a sense of the impact of haplotype error under realistic scenarios and underscore the importance of high-quality genotyping, in which case the bias in haplotype association estimates is negligible
    Type of Publication: Journal article published
    PubMed ID: 20649529
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  • 8
    Keywords: Germany ; MODEL ; DISEASE ; GENE ; SAMPLE ; IMPACT ; ASSOCIATION ; FREQUENCIES ; PERFORMANCE ; genetics ; RATES ; REPLICATION ; UNCERTAINTY ; transmission/disequilibrium test ; TESTS ; ERROR ; HARDY-WEINBERG EQUILIBRIUM ; ROBUST ; CONTROL GENETIC ASSOCIATION ; MISCLASSIFICATION ; TAGGING SNP SELECTION
    Abstract: Background: We investigated the influence of genotyping errors on the type I error rate and empirical power of two haplotype based association methods applied to candidate regions. We compared the performance of the Mantel Statistic Using Haplotype Sharing and the haplotype frequency based score test with that of the Armitage trend test. Our study is based on 1000 replication of simulated case-control data settings with 500 cases and 500 controls, respectively. One of the examined markers was set to be the disease locus with a simulated odds ratio of 3. Differential and non-differential genotyping errors were introduced following a misclassification model with varying mean error rates per locus in the range of 0.2% to 15.6%. Results: We found that the type I error rate of all three test statistics hold the nominal significance level in the presence of nondifferential genotyping errors and low error rates. For high and differential error rates, the type I error rate of all three test statistics was inflated, even when genetic markers not in Hardy-Weinberg Equilibrium were removed. The empirical power of all three association test statistics remained high at around 89% to 94% when genotyping error rates were low, but decreased to 48% to 80% for high and nondifferential genotyping error rates. Conclusion: Currently realistic genotyping error rates for candidate gene analysis (mean error rate per locus of 0.2%) pose no significant problem for the type I error rate as well as the power of all three investigated test statistics
    Type of Publication: Journal article published
    PubMed ID: 19178712
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  • 9
    Abstract: Recent studies strongly support an association of the nicotinic acetylcholine receptor gene cluster CHRNA5-CHRNA3-CHRNB4 with nicotine dependence (ND). However, the precise genotype-phenotype relationship is still unknown. Clinical and epidemiological data on smoking behavior raise the possibility that the relevant gene variants may indirectly contribute to the development of ND by affecting cognitive performance in some smokers who consume nicotine for reasons of "cognition enhancement." Here, we tested seven single nucleotide polymorphisms (SNPs) rs684513, rs637137, rs16969968, rs578776, rs1051730, rs3743078, rs3813567 from the CHRNA5-CHRNA3-CHRNB4 gene cluster for association with ND, measures of cognitive performance and gene expression. As expected, we found all SNPs being associated with ND in three independent cohorts (KORA, NCOOP, ESTHER) comprising 5,561 individuals. In an overlapping sample of 2,186 subjects we found three SNPs (rs16969968, rs1051730, rs3743078) being associated with cognitive domains from the Wechsler-Adult-Intelligence Scale (WAIS-R)-most notably in the performance subtest "object assembly" and the verbal subtest "similarities." In a refined analysis of a subsample of 485 subjects, two of these three SNPs (rs16969968, rs1051730) were associated with n-back task performance/Continuous Performance Test. Furthermore, two CHRNA5 risk alleles (rs684513, rs637137) were associated with CHRNA5 mRNA expression levels in whole blood in a subgroup of 190 subjects. We here report for the first time an association of CHRNA5-CHRNA3-CHRNB4 gene variants with cognition possibly mediating in part risk for developing ND. The observed phenotype-genotype associations may depend on altered levels of gene expression.
    Type of Publication: Journal article published
    PubMed ID: 20886544
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  • 10
    Keywords: RECEPTOR ; KINASE ; PROTEIN ; ACTIVATION ; CELL-LINES ; METASTASIS ; SIGNALING PATHWAY ; CROSS-TALK ; EXPRESSION PROFILES ; LATE ENDOSOMES
    Abstract: BACKGROUND: The late endosomal LAMTOR complex serves as a convergence point for both the RAF/MEK/ERK and the PI3K/AKT/mTOR pathways. Interestingly, both of these signalling cascades play a significant role in the aetiology of breast cancer. Our aim was to address the possible role of genetic polymorphisms in LAMTOR2 and LAMTOR3 as genetic risk factors for breast cancer. METHODOLOGY/RESULTS: We sequenced the exons and exon-intron boundaries of LAMTOR2 (p14) and LAMTOR3 (MP1) in 50 prospectively collected pairs of cancerous tissue and blood samples from breast cancer patients and compared their genetic variability. We found one single nucleotide polymorphism (SNP) in LAMTOR2 (rs7541) and two SNPs in LAMTOR3 (rs2298735 and rs148972953) in both tumour and blood samples, but no somatic mutations in cancerous tissues. In addition, we genotyped all three SNPs in 296 samples from the Risk Prediction of Breast Cancer Metastasis Study and found evidence of a genetic association between rs148972953 and oestrogen (ER) and progesterone receptor negative status (PR) (ER: OR = 3.60 (1.15-11.28); PR: OR = 4.27 (1.43-12.72)). However, when we additionally genotyped rs148972953 in the MARIE study including 2,715 breast cancer cases and 5,216 controls, we observed neither a difference in genotype frequencies between patients and controls nor was the SNP associated with ER or PR. Finally, all three SNPs were equally frequent in breast cancer samples and female participants (n = 640) of the population-based SAPHIR Study. CONCLUSIONS: The identified polymorphisms in LAMTOR2 and LAMTOR3 do not seem to play a relevant role in breast cancer. Our work does not exclude a role of other not yet identified SNPs or that the here annotated polymorphism may in fact play a relevant role in other diseases. Our results underscore the importance of replication in association studies.
    Type of Publication: Journal article published
    PubMed ID: 23341997
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