Thomas Fiedler

Heterozygosity for IL23R p.Arg381Gln confers a protective effect not only against Crohn’s disease but also ulcerative colitis

Background  A recent study reported that a non‐synonymous single nucleotide polymorphism (rs11209026, p.Arg381Gln) located in the IL23R gene is a protective marker for inflammatory bowel disease.

DLG5 Variants in Inflammatory Bowel Disease

OBJECTIVES:Genetic variants within DLG5 were recently reported to be associated with inflammatory bowel disease (IBD). The aim of our study was to test for allelic and haplotype associations of six DLG5 variants in 668 IBD patients from two European populations. Furthermore, we evaluated whether DLG5 variants alter gastrointestinal permeability in Crohns disease (CD).METHODS:Six DLG5 variants (p.R30Q, p.P1371Q, p.G1066G, rs2289308, DLG_e26, p.D1507D) were genotyped in two study populations: (1) German IBD patients (CD n = 250; ulcerative colitis (UC) n = 150) and German healthy controls (n = 422); (2) Hungarian IBD patients (CD n = 144; UC n = 124) and Hungarian healthy controls (n = 205). Subtyping analysis was performed in respect of CARD15 mutations and clinical characteristics. We also tested for differences within DLG5 genotypes in German CD patients with respect to gastroduodenal and intestinal permeability measured by triple-sugar-test.RESULTS:Allele as well as genotype frequencies of DLG5 variants did not differ between IBD patients and controls in either study population. Indeed, the p.R30Q polymorphism was found more frequently in controls than in patients. The distribution of DLG5 genotypes in German and Hungarian CD patients with CARD15 mutations was not different from patients without mutated CARD15. We did also not observe any association between DLG5 variants and clinical parameters. Importantly, DLG5 variants were not associated with gastroduodenal or intestinal permeability.CONCLUSIONS:We could not replicate that DLG5 is a relevant disease susceptibility gene for IBD in German or Hungarian subjects. In addition, we have no evidence that DLG5 variants are involved in altered gastrointestinal permeability in CD.

Introducing Genetic Testing for Adult-Type Hypolactasia

Background and Aims: To evaluate genotyping for two DNA variants (c.1993+327C>T and c.1438+117G>A), recently found to be associated with adult-type hypolactasia, in the diagnosis of lactose intolerance. Methods: In total, 166 consecutive patients with gastrointestinal symptoms mimicking hypolactasia admitted to the clinic between March 2002 and December 2002 were included. Genotyping for the two DNA variants (c.1993+327C>T and c.1438+117G>A) and standard H2 breath test was performed. Results: Among 116 patients with positive H2 breath test, the c.1993+327C variantwas detectablein 106 (91.4%) patients. Among 50 patients with negative H2 breath test, the c.1993+327Cvariantwas seen in 2 patients. Sensitivity, specificity, positive and negative predictive values for the c.1993+327C variant were 91.4, 96.0, 98.1 and 82.8%, respectively. Genotyping for the c.1438+117G variant did not bring any additional information. Among 4 of the 10 patients with positive H2 breath test but negative for the c.1993+327C and the c.1438+117G variant,further evaluation revealed other diseases known to cause secondary hypolactasia such as celiac disease and short bowel syndrome. Conclusion: In symptomatic patients, genotyping for the DNA variant c.1993+327C is a reliable test for adult-type hypolactasia with high sensitivity and specificity and thus provides a new tool in the diagnostic workup of hypolactasia.

Possible role of MDR1 two-locus genotypes for young-age onset ulcerative colitis but not Crohn's disease

BackgroundThe role of the single nucleotide polymorphisms (SNPs) on positions 2677G>T/A and 3435C>T of the multi-drug-resistance gene 1 (MDR1) in inflammatory bowel disease (IBD) remains unclear.AimsTo further elucidate the potential impact of MDR1 two-locus genotypes on susceptibility to IBD and disease behaviour.Patients and methodsThree hundred eighty-eight German IBD patients [244 with Crohn’s disease (CD), 144 with ulcerative colitis (UC)] and 1,005 German healthy controls were genotyped for the two MDR1 SNPs on positions 2677G>T/A and 3435C>T. Genotype–phenotype analysis was performed with respect to disease susceptibility stratified by age at diagnosis as well as disease localisation and behaviour.ResultsGenotype distribution did not differ between all UC or CD patients and controls. Between UC and CD patients, however, we observed a trend of different distribution of the combined genotypes derived from SNPs 2677 and 3435 (χ2 = 15.997, df = 8, p = 0.054). In subgroup analysis, genotype frequencies between UC patients with early onset of disease and controls showed significant difference for combined positions 2677 and 3435 (χ2 = 16.054, df = 8, p = 0.034 for age at diagnosis ≥25, lower quartile). Herein the rare genotype 2677GG/3435TT was more frequently observed (odds ratio = 7.0, 95% confidence interval 2.5 – 19.7). In this group severe course of disease behaviour depended on the combined MDR1 SNPs (χ2 = 16.101, df = 6, p = 0.017 for age at diagnosis ≥25). No association of MDR1 genotypes with disease subgroups in CD was observed.ConclusionsWhile overall genotype distribution did not differ, combined MDR1 genotypes derived from positions 2677 and 3435 are possibly associated with young age onset of UC and severe course of disease in this patient group.

The c.1-260C>T promoter variant of CD14 but not the c.896A>G (p.D299G) variant of toll-like receptor 4 (TLR4) genes is associated with inflammatory bowel disease.

Background: Inflammatory bowel disease (IBD) results from an aberrant immune response to the indigenous intestinal flora in genetically susceptible hosts. Therefore, the study of candidate genes involved in host pathogen interactions is of key interest. Methods: In this two-center, retrospective German and Hungarian cohort study, patients with Crohn’s disease (CD) (n = 379; German n = 235, Hungarian n = 144) and ulcerative colitis (UC) (n = 263; German n = 145, Hungarian n = 118) and healthy controls (n = 605; German n = 403, Hungarian n = 202) were genotyped for the presence of the CD14 c.1-260C>T promoter variant and the TLR4 c.896A>G (p.D299G) variant by melting curve analysis using fluorescence resonance energy transfer probes. Data were stratified according to the presence of NOD2 (CARD15) mutations and a detailed genotype-phenotype analysis was performed. Results: In the German cohort the CD14 single-nucleotide polymorphism was associated with UC, but not CD (UC p = 0.016 vs. CD p = 0.190), while the opposite was found in the Hungarian cohort (UC p = 0.083 vs. CD p = 0.019). No association of IBD with the TLR4 single-nucleotide polymorphism was found in either cohort (UC p = 0.430, CD p = 0.783 vs. UC p = 0.745, CD p = 0.383). Conclusion: IBD appears to be associated with the CD14 c.1-260C>T promoter variant in Germans and Hungarians, but not with the TLR4 c.896A>G (p.D299G) variant.

No association of the CARD8 (TUCAN) c.30T>A (p.C10X) variant with Crohn's disease: a study in 3 independent European cohorts.

Background: A recent study reported that the c.30T>A (p.Cys10Ter; rs2043211) variant, in the CARD8 (TUCAN) gene, is associated with Crohns disease (CD). The aim of this study was to analyze the frequency of p.C10X in 3 independent European (IBD) cohorts from Germany, Hungary, and the Netherlands. Methods: We included a European IBD cohort of 921 patients and compared the p.C10X genotype frequency to 832 healthy controls. The 3 study populations analyzed were: (1) Germany [CD, n = 317; ulcerative colitis (UC), n = 180], (2) Hungary (CD, n = 149; UC, n = 119), and (3) the Netherlands (CD, n = 156). Subtyping analysis was performed in respect to NOD2 variants (p.Arg702Trp, p.Gly908Arg, c.3020insC) and to clinical characteristics. Ethnically matched controls were included (German, n = 413; Hungarian, n = 202; Dutch, n = 217). Results: We observed no significant difference in p.C10X genotype frequency in either patients with CD or patients with UC compared with controls in all 3 cohorts. Conversely to the initial association study, we found a trend toward lower frequencies of the suggestive risk wild type in CD from the Netherlands compared with controls (P = 0.14). We found neither evidence for genetic interactions between p.C10X and NOD2 nor the C10X variant to be associated with a CD or UC phenotype. Conclusions: Analyzing 3 independent European IBD cohorts, we found no evidence that the C10X variant in CARD8 confers susceptibility for CD.

A study in three European IBD cohorts confirms that the ATG16L1 c.898A > G (p.Thr300Ala) variant is a susceptibility factor for Crohn’s disease

BACKGROUND AND AIMS A recent study reported that a nonsynonymous SNP rs2241880 (c.898A>G, p.Thr300Ala) within ATG16L1 confers susceptibility to Crohns disease (CD). We analyzed ATG16L1 c.898A>G in three independent European inflammatory bowel disease (IBD) cohorts from Germany, Hungary and the Netherlands. METHODS In total, we included 910 European IBD patients and compared the ATG16L1 c.898A>G genotype frequency with 707 ethnically matched healthy controls. We included patients from 3 populations originating from Germany (CD n=310; ulcerative colitis [UC] n=179), Hungary (CD n=147; UC n=117), and the Netherlands (CD n=157). Subtyping analysis was performed in respect to CARD15 alterations and clinical characteristics. RESULTS We found a highly significant association of c.898A>G to CD. The association was significant (p=0.0005) for the total CD cohort but also for the individual populations from Germany (p=0.02) and Netherlands (p=0.02) whereas in the Hungarian CD patients a clear trend was observed (p=0.19; OR 1.227, 95% CI 0.910; 1.654). No association was found between c.898A>G and UC. No statistical interactions were observed between ATG16L1 c.898A>G and CARD15 variants. Furthermore no association to a CD subphenotype was detected. CONCLUSIONS We confirm that ATG16L1 variant c898A>G confers a risk variant for CD but is not associated with a distinct CD phenotype.

Contents Vol. 76, 2007

C. Beglinger, Basel (Switzerland) B. Göke, Munich (Germany) International Journal of Gastroenterology Founded as ‘Archiv für Verdauungskrankheiten’ 1895 by I. Boas Continued as ‘Gastroenterologia’ 1939–1967 Former Editors: P. Morawitz (1934–1936), R. Staehelin (1937–1943), A. Hurst (1940–1945), W. Löffl er (1943–1961), T.C. Hunt (1947–1967), N. Henning (1953–1962), B. Ihre (1953–1967), H. Bartelheimer (1963–1967), M. Demole (1963–1971), H. Kapp (1968–1970), R. Lambert (1972–1978), W. Creutzfeldt (1979–1992), R. Arnold (1993–2003)