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  • Inherited determinants of Crohn's disease and ulcerative colitis phenotypes [Elektronski vir] : a genetic association study
    Cleynen, Isabelle ...
    Background Crohn's disease and ulcerative colitis are the two major forms of inflammatory bowel disease; treatment strategies have historically been determined by this binary categorisation. Genetic ... studies have identified 163 susceptibility loci for inflammatory bowel disease, mostly shared between Crohn's disease and ulcerative colitis. We undertook the largest genotype association study, to date, in widely used clinical subphenotypes of inflammatory bowel disease with the goal of further understanding the biological relations between diseases. Methods This study included patients from 49 centres in 16 countries in Europe, North America, and Australasia. We applied the Montreal classification system of inflammatory bowel disease subphenotypes to 34819 patients (19713 with Crohn's disease, 14683 with ulcerative colitis) genotyped on the Immunochip array. We tested for genotype-phenotype associations across 156154 genetic variants. We generated genetic risk scores by combining information from all known inflammatory bowel disease associations to summarise the total load of genetic risk for a particular phenotype. We used these risk scores to test the hypothesis that colonic Crohn's disease, ileal Crohn's disease, and ulcerative colitis are all genetically distinct from each other, and to attempt to identify patients with a mismatch between clinical diagnosis and genetic risk profile. Findings After quality control, the primary analysis included 29838 patients (16902 with Crohn's disease, 12597 with ulcerative colitis). Three loci (NOD2, MHC, and MST1 3p21) were associated with subphenotypes of inflammatory bowel disease, mainly disease location (essentially fixed over time; median follow-up of 10-5 years). Little or no genetic association with disease behaviour (which changed dramatically over time) remained after conditioning on disease location and age at onset. The genetic risk score representing all known risk alleles for inflammatory bowel disease showed strong association with disease subphenotype (p=1 65X1078), even after exclusion of NOD2, MHC, and 3p21 (p=9 23 x 10 18). Predictive models based on the genetic risk score strongly distinguished colonic from ileal Crohn's disease. Our genetic risk score could also identify a small number of patients with discrepant genetic risk profiles who were significantly more likely to have a revised diagnosis after follow-up (p=6%8%%%10%4). Interpretation Our data support a continuum of disorders within inflammatory bowel disease, much better explained by three groups (ileal Crohn's disease, colonic Crohn's disease, and ulcerative colitis) than by Crohn's disease and ulcerative colitis as currently defined. Disease location is an intrinsic aspect of a patient's disease, in part genetically determined, and the major driver to changes in disease behaviour over time.
    Source: The Lancet [Elektronski vir]. - ISSN 1474-547X (Vol. 387, iss. 10014, 2016, str. 156-167)
    Type of material - e-article
    Publish date - 2016
    Language - english
    COBISS.SI-ID - 512567352

    Link(s):

    http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(15)00465-1/abstract
    DOI

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