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Genotype-phenotype analysis of the Crohn's disease susceptibility haplotype on chromosome 5q31.

ABSTRACT: BACKGROUND AND AIMS:Recent molecular data suggest that genetic factors may underlie the disease heterogeneity observed in both ulcerative colitis (UC) and Crohn's disease (CD). A locus on chromosome 5q has been implicated in susceptibility to CD, and recently refined by linkage disequilibrium mapping to a conserved 250 kb haplotype (5q31). No data regarding the contribution of this locus to clinical phenotype exist. In this case control study, we investigated the contribution of this haplotype to both susceptibility and phenotype of CD and UC. PATIENTS AND METHODS:We studied 330 Caucasian CD and 457 UC patients recruited from a single UK centre. Association with disease susceptibility and phenotype was analysed with haplotypes reconstructed from three single nucleotide polymorphisms chosen to span this susceptibility region. Evidence for possible genetic epistasis between IBD5 and NOD2/CARD15 was sought. RESULTS:Linkage disequilibrium across this region was confirmed, with two haplotypes comprising 88% of all chromosomes. Susceptibility to CD, but not to UC, was associated with homozygosity for a common haplotype, H2 (p(c)=0.002; relative risk (RR) 2.0). Genotype-phenotype analyses demonstrated that this association was particularly strong in patients with perianal disease (p(c)=0.0005; RR 1.7), especially in individuals homozygous for this haplotype (p(c)=0.0005; RR 3.0). Importantly, no association with H2 was found in 186 patients without perianal disease. No evidence of epistasis between IBD5 and NOD2/CARD15 was demonstrated. CONCLUSIONS:The IBD5 risk haplotype is associated with CD only. Genotype-phenotype analysis reveals that the strongest association is observed in patients with perianal CD. While the precise gene involved is unclear, these data provide further molecular evidence for a genetic basis of the clinical heterogeneity of CD.

SUBMITTER: Armuzzi A

PROVIDER: S-EPMC1773736 | biostudies-literature | 2003 Aug

REPOSITORIES: biostudies-literature

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Genotype-phenotype analysis of the Crohn's disease susceptibility haplotype on chromosome 5q31.

Armuzzi A A Ahmad T T Ling K-L KL de Silva A A Cullen S S van Heel D D Orchard T R TR Welsh K I KI Marshall S E SE Jewell D P DP

Gut 20030801 8

<h4>Background and aims</h4>Recent molecular data suggest that genetic factors may underlie the disease heterogeneity observed in both ulcerative colitis (UC) and Crohn's disease (CD). A locus on chromosome 5q has been implicated in susceptibility to CD, and recently refined by linkage disequilibrium mapping to a conserved 250 kb haplotype (5q31). No data regarding the contribution of this locus to clinical phenotype exist. In this case control study, we investigated the contribution of this hap ...[more]

PMID: 12865271

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Project description:AimTo investigate genotype-phenotype correlations in patients with perianal Crohn's disease (PCD) in order to determine which factors predispose to development of perianal disease in Crohn's patients.MethodsSeven-hundred and ninety-five Caucasian individuals (317 CD patients and 478 controls without inflammatory bowel disease, IBD) were prospectively enrolled into a clinical/genetic database. Demographic and clinical data, as well as peripheral blood leukocyte DNA were obtained from all patients. The following were evaluated: three NOD2/CARD15 polymorphisms: R702W, G908R, and 1007insC; five IL-23r risk alleles: rs1004819, rs10489629, rs2201841, rs11465804, and rs11209026; a well-characterized single-nucleotide polymorphism (SNP) on the IBD5 risk haplotype (OCTN1) and two peripheral tag SNPs (IGR2060 and IGR3096).ResultsPCD occurred in 147 (46%) of CD patients. There was no significant difference in the age at disease diagnosis between non-PCD and PCD patients (33 vs. 29 years, respectively). PCD patients were more likely to have disease located in the colon and ileocolic regions (79 PCD vs. 57% non-PCD; n = 116 vs. n = 96; p < 0.001), whereas patients with non-PCD were more likely to have Crohn's within the terminal ileum and upper gastrointestinal tract (43% non-PCD vs. 21% PCD; n = 73 vs. n = 31; p < 0.05). Thirty-four percent of patients with PCD required a permanent ileostomy (n = 50) compared to only 4% of non-PCD patients (n = 6; p < 0.05). Mutations in CARD15/NOD2 and IL-23r were risk factors for CD overall; however, in contrast to prior reports, in this patient population, OCTN1 and IGR variations within the IBD5 haplotype were not significant predictors of PCD.ConclusionColon/ileocolic CD location appears to be a significant predictor of perianal manifestations of CD. Patients with PCD are more likely to require permanent fecal diversion. We did not identify any genetic variations or combination of clinical findings and genetic variations within the CARD15/NOD2, IL-23r, and OCTN1 genes or IGR that were predictive of PCD.

Dataset Information

Genotype-phenotype analysis of the Crohn's disease susceptibility haplotype on chromosome 5q31.

Publications

Genotype-phenotype analysis of the Crohn's disease susceptibility haplotype on chromosome 5q31.

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