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Background: Genome-wide association studies identified a PTGER4 expression-modulating region on chromosome 5p13.1 as Crohn's disease (CD) susceptibility region. The study aim was to test this association in a large cohort of patients with inflammatory bowel disease (IBD) and to elucidate genotypic and phenotypic interactions with other IBD genes. Methodology/Principal Findings: A total of 7073 patients and controls were genotyped: 844 CD and 471 patients with ulcerative colitis and 1488 controls were analyzed for the single nucleotide polymorphisms (SNPs) rs4495224 and rs7720838 on chromosome 5p13.1. The study included two replication cohorts of North American (CD: n = 684; controls: n = 1440) and of German origin (CD: n = 1098; controls: n = 1048). Genotype-phenotype, epistasis and transcription factor binding analyses were performed. In the discovery cohort, an association of rs4495224 (p = 4.10×10-5; 0.76 [0.67-0.87]) and of rs7720838 (p = 6.91×10-4; 0.81 [0.71-0.91]) with susceptibility to CD was demonstrated. These associations were confirmed in both replication cohorts. In silico analysis predicted rs4495224 and rs7720838 as essential parts of binding sites for the transcription factors NF-κB and XBP1 with higher binding scores for carriers of the CD risk alleles, providing an explanation of how these SNPs might contribute to increased PTGER4 expression. There was no association of the PTGER4 SNPs with IBD phenotypes. Epistasis detected between 5p13.1 and ATG16L1 for CD susceptibility in the discovery cohort (p = 5.99×10-7 for rs7720838 and rs2241880) could not be replicated in both replication cohorts arguing against a major role of this gene-gene interaction in the susceptibility to CD. Conclusions/Significance: We confirmed 5p13.1 as a major CD susceptibility locus and demonstrate by in silico analysis rs4495224 and rs7720838 as part of binding sites for NF-κB and XBP1. Further functional studies are necessary to confirm the results of our in silico analysis and to analyze if changes in PTGER4 expression modulate CD susceptibility. [ABSTRACT FROM AUTHOR]

To cite this article: Toncheva AA, Suttner K, Michel S, Klopp N, Illig T, Balschun T, Vogelberg C, von Berg A, Bufe A, Heinzmann A, Laub O, Rietschel E, Simma B, Frischer T, Genuneit J, von Mutius E, Kabesch M. Genetic variants in Protocadherin-1, bronchial hyper-responsiveness, and asthma subphenotypes in German children. Pediatr Allergy Immunol 2012. Abstract Background: Recently, Protocadherin-1 ( PCDH1) was reported as a novel susceptibility gene for bronchial hyper-responsiveness (BHR) and asthma. PCDH1 is located on chromosome 5q31-33, in the vicinity of several known candidate genes for asthma and allergy. To exclude that the associations observed for PCDH1 originate from the nearby cytokine cluster, an extensive linkage disequilibrium (LD) analysis was performed. Effects of polymorphisms in PCDH1 on asthma, BHR, and related phenotypes were studied comprehensively. Methods: Genotype information was acquired from Illumina HumanHap300Chip genotyping, MALDI-TOF MS genotyping, and imputation. LD was assessed by Haploview 4.2 software. Associations were investigated in a population of 1454 individuals (763 asthmatics) from two German study populations [MAGICS and International Study of Asthma and Allergies in Childhood phase II (ISAAC II)] using logistic regression to model additive effects. Results: No relevant LD between PCDH1 tagging polymorphisms and 98 single nucleotide polymorphisms within the cytokine cluster was detected. While BHR was not associated with PCDH1 polymorphisms, significant associations with subphenotypes of asthma were observed. Conclusion: Protocadherin-1 polymorphisms may specifically affect the development of non-atopic asthma in children. Functional studies are needed to further investigate the role of PCDH1 in BHR and asthma development. [ABSTRACT FROM AUTHOR]

We undertook a meta-analysis of six Crohn's disease genome-wide association studies (GWAS) comprising 6,333 affected individuals (cases) and 15,056 controls and followed up the top association signals in 15,694 cases, 14,026 controls and 414 parent-offspring trios. We identified 30 new susceptibility loci meeting genome-wide significance (P < 5 × 10−8). A series of in silico analyses highlighted particular genes within these loci and, together with manual curation, implicated functionally interesting candidate genes including SMAD3, ERAP2, IL10, IL2RA, TYK2, FUT2, DNMT3A, DENND1B, BACH2 and TAGAP. Combined with previously confirmed loci, these results identify 71 distinct loci with genome-wide significant evidence for association with Crohn's disease. [ABSTRACT FROM AUTHOR]

Background: TGR5, the G protein-coupled bile acid receptor 1 (GPBAR1), has been linked to inflammatory pathways as well as bile homeostasis, and could therefore be involved in primary sclerosing cholangitis (PSC) a chronic inflammatory bile duct disease. We aimed to extensively investigate TGR5 sequence variation in PSC, as well as functionally characterize detected variants. Methodology/Principal Findings: Complete resequencing of TGR5 was performed in 267 PSC patients and 274 healthy controls. Six nonsynonymous mutations were identified in addition to 16 other novel single-nucleotide polymorphisms. To investigate the impact from the nonsynonymous variants on TGR5, we created a receptor model, and introduced mutated TGR5 constructs into human epithelial cell lines. By using confocal microscopy, flow cytometry and a cAMP-sensitive luciferase assay, five of the nonsynonymous mutations (W83R, V178M, A217P, S272G and Q296X) were found to reduce or abolish TGR5 function. Fine-mapping of the previously reported PSC and UC associated locus at chromosome 2q35 in large patient panels revealed an overall association between the TGR5 single-nucleotide polymorphism rs11554825 and PSC (odds ratio = 1.14, 95% confidence interval: 1.03-1.26, p = 0.010) and UC (odds ratio = 1.19, 95% confidence interval 1.11- 1.27, p = 8.5×10-7), but strong linkage disequilibrium precluded demarcation of TGR5 from neighboring genes. Conclusions/Significance: Resequencing of TGR5 along with functional investigations of novel variants provided unique insight into an important candidate gene for several inflammatory and metabolic conditions. While significant TGR5 associations were detected in both UC and PSC, further studies are needed to conclusively define the role of TGR5 variation in these diseases [ABSTRACT FROM AUTHOR]

OBJECTIVES:Genetic susceptibility is known to make a major contribution to the pathogenesis of ulcerative colitis (UC). Recently, three studies, including a genome-wide association study (GWAS), reported novel UC risk loci.METHODS:The top-20 single-nucleotide polymorphisms (SNPs) from the first UC-GWAS were genotyped, as part of the study's replication phase, in 561 UC cases and 728 controls from our Dutch UC study sample. We genotyped eight SNPs identified in two more studies, in these individuals, and replicated all significantly associated SNPs in an additional 894 UC cases and 1,174 controls from our Dutch UC study sample. A combined analysis for all patients (n=1,455) and controls (n=1,902) was performed. Dose–response models were constructed with the associated risk alleles.RESULTS:We found 12 SNPs tagging ten loci, including HLA-DRA, IL10, IL23R, JAK2, S100Z, ARPC2, and ECM1, to be associated with UC. We identified 10q26, flagged by the UC-GWAS but not confirmed in its replication phase, as a UC locus and found a trend toward association for GAS7. No association with disease localization or severity was found. The dose–response models show that individuals carrying 11 or more risk alleles have an odds ratio of 8.2 (confidence interval 3.0–22.8) for UC susceptibility.CONCLUSIONS:We confirmed the association of multiple loci with UC in the Dutch population and found evidence for association of 10q26 and a trend suggesting association for GAS7. Genetic models show that multiple risk loci in an individual increase the risk for developing UC. [ABSTRACT FROM AUTHOR]

Inflammatory bowel disease (IBD) typically manifests as either ulcerative colitis (UC) or Crohn's disease (CD). Systematic identification of susceptibility genes for IBD has thus far focused mainly on CD, and little is known about the genetic architecture of UC. Here we report a genome-wide association study with 440,794 SNPs genotyped in 1,167 individuals with UC and 777 healthy controls. Twenty of the most significantly associated SNPs were tested for replication in three independent European case-control panels comprising a total of 1,855 individuals with UC and 3,091 controls. Among the four consistently replicated markers, SNP rs3024505 immediately flanking the IL10 (interleukin 10) gene on chromosome 1q32.1 showed the most significant association in the combined verification samples (P = 1.35 × 10−12; OR = 1.46 (1.31–1.62)). The other markers were located in ARPC2 and in the HLA-BTNL2 region. Association between rs3024505 and CD (1,848 cases, 1,804 controls) was weak (P = 0.013; OR = 1.17 (1.01–1.34)). IL10 is an immunosuppressive cytokine that has long been proposed to influence IBD pathophysiology. Our findings strongly suggest that defective IL10 function is central to the pathogenesis of the UC subtype of IBD. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article which discusses the study conducted by I. Surolia and colleagues, on the disassociation of sialic acid acetylesterase (SIAE) with immunie disease in European ancestry.

Primary sclerosing cholangitis (PSC) is a chronic bile duct disease affecting 2.4-7.5% of individuals with inflammatory bowel disease. We performed a genome-wide association analysis of 2,466,182 SNPs in 715 individuals with PSC and 2,962 controls, followed by replication in 1,025 PSC cases and 2,174 controls. We detected non-HLA associations at rs3197999 in MST1 and rs6720394 near BCL2L11 (combined P = 1.1 × 10−16 and P = 4.1 × 10−8, respectively). [ABSTRACT FROM AUTHOR]

We performed a genome-wide association analysis of 1,897,764 SNPs in 1,043 German ulcerative colitis (UC) cases and 1,703 controls. We discovered new associations at chromosome 7q22 (rs7809799) and at chromosome 22q13 in IL17REL (rs5771069) and confirmed these associations in six replication panels (2,539 UC cases and 5,428 controls) from different regions of Europe (overall study sample Prs7809799 = 8.81 × 10−11 and Prs5771069 = 4.21 × 10−8, respectively). [ABSTRACT FROM AUTHOR]

Following up on recent genome-wide association studies (GWAS) of Crohn's disease, we investigated 50 previously reported susceptibility loci in a German sample of individuals with Crohn's disease (n = 1,850) or ulcerative colitis (n = 1,103) and healthy controls (n = 1,817). Among these loci, we identified variants in 3p21.31, NKX2-3 and CCNY as susceptibility factors for both diseases, whereas variants in PTPN2, HERC2 and STAT3 were associated only with ulcerative colitis in our sample collection. [ABSTRACT FROM AUTHOR]

A correction to the article "Genetic Analysis in A Dutch Study Sample Identifi es More Ulcerative Colitis Susceptibility Loci and Shows Their Additive Role in Disease Risk" that was published in the previous issue is presented.