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Query: UMLS:C0010346 (Crohn's disease)
 21,615 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Linkage studies have identified the inflammatory bowel disease (IBD)1 locus on chromosome 16 and the IBD2 locus on chromosome 12 to be involved in Crohn's disease. NOD2/CARD15 was identified as the gene of interest within the IBD1 region. However, linkage to this region could not be explained by NOD2/CARD15 alone. Here we set out to assess the association of additional candidate genes from the IBD1 and IBD2 loci with Crohn's disease using transmission disequilibrium testing in patient-parent triads. No significant association was observed with genetic variants in the genes coding for interleukin-4 receptor gene (IL-4R), CD11B and signal transducer and activator of transcription type 6 (STAT6). Results for IL-4R were not affected by exclusion of all families carrying one of three risk alleles in NOD2. From this we conclude that IL-4R and CD11B in the IBD1 region and STAT6 in the IBD2 region are not involved in Crohn's disease in this Dutch cohort.
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PMID:No evidence for involvement of IL-4R and CD11B from the IBD1 region and STAT6 in the IBD2 region in Crohn's disease. 1457 Dec 75

Strong epidemiological evidence for a genetic contribution to pathogenesis in inflammatory bowel disease (IBD) has stimulated efforts to identify susceptibility genes for both of its major clinical forms, Crohn's disease and ulcerative colitis. Genome scans for linkage have indicated multiple regions of interest, but replication of these has been limited. The detection of linkage on chromosome 16 (IBD1) led to the unequivocal identification of the NOD2 gene (now called CARD15) as a susceptibility gene for Crohn's disease. This seminal discovery has provided proof of principle for positional cloning and candidate gene approaches to identify IBD genes. It has also led to useful strategic insights in complex disease genetics, and generated new directions in the investigation of the molecular pathways to pathogenesis. Linkage and association studies have also provided strong support for IBD susceptibility genes on chromosomes 5q31, 6p21 and 19p, while loci of interest at 3p, 3q and 14q require further follow-up. Although important obstacles to further progress will need to be overcome, the successes of the past 2 years suggest that a detailed description of the genetic basis of inflammatory bowel disease is a realistic goal.
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PMID:Genetics of inflammatory bowel disease: progress and prospects. 1476 25

The past decade has witnessed a tremendous expansion of our knowledge-base of genetics of inflammatory bowel disease. To a large extent, this progress reflects the scientific innovation and impact of the human genome project, which has fueled many laboratory-based studies focusing on the molecular genetics of Crohn's disease and ulcerative colitis. The complementary strategies of genome-wide linkage scanning and candidate gene analysis uncovered a number of genetic loci associated with IBD susceptibility. Notably, the identification of the IBD1 and IBD5 loci is a major scientific discovery. Although many issues related to the function and expression of these genes await elucidation, there is a shared optimism that pivotal clinical applications will emerge from these investigations.
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PMID:Genome scan analyses and positional cloning strategy in IBD: successes and limitations. 1515 26

Observed inflammatory bowel disease (IBD) familial clustering and increased monozygotic twin concordance has led to the hypothesis that genetic loci containing IBD susceptibility genes can be identified by whole genome linkage mapping approaches. Methodology including collecting carefully phenotyped multiplex pedigrees, genotyping using highly informative microsatellite markers and linkage analysis by non-parametric allele sharing methods has been established. Eleven published genome wide screens (GWS) have studied more than 1,200 multiplex IBD pedigrees. Two-thirds of affected relative pairs were Crohn's disease (CD), 20% ulcerative colitis (UC) and the remaining were mixed. Seven loci (IBDI-7) on chromosomes 16q, 12, 6p, 14q, 5q, 19, and 1p have been identified with genome wide significant and independently replicated linkage. Risk alleles/haplotypes have been defined for the IBD1 (CARD15/NOD2), IBD3 (HLA) and IBD5 (5q cytokine cluster) loci. There has been evidence for a second chromosome 16 locus (IBD8) independent of NOD2 that overlaps IBD1 on the pericentromeric p-arm. Several other regions show great promise for containing additional IBD loci, particularly chromosome 3p with genome wide evidence in one study at 3p26 and more centromeric evidence in several other studies, and chromosomes 2q, 3q, 4q, 7, 11p, and Xp each with suggestive evidence of linkage in one and additional evidence in two or more studies. Single GWSs and fine mapping studies containing very large sets of pedigrees and in particular, more UC pedigrees, and the use of creative analytic and disease stratification schemes are required to identify, establish and refine weaker IBD loci.
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PMID:Inflammatory bowel disease gene hunting by linkage analysis: rationale, methodology, and present status of the field. 1529 Sep 27

Inflammatory bowel disease (IBD) has a multifactorial etiology and includes ulcerative colitis (UC) and Crohn's disease (CD). Powerful epidemiologic and genetic studies have provided ample evidence that a subset of both CD and UC are attributable to a likely primary genetic etiology. This is evidenced by the recent identification of the IBD1 gene ( NOD2 ) mutations which show an association with susceptibility to CD. The IBD complex shows a significant increased frequency in Jews when compared to non-Jews. While there is an increased incidence of colorectal cancer (CRC) in patients with IBD, it nevertheless is important to realize that IBD likely accounts for no more than 1-3% of all cases of CRC in Ashkenazi Jews. Importantly, however, awareness of the increased CRC risk in IBD may aid immeasurably in preventive interventions. The molecular pathway leading to CRC in IBD appears to differ from the well-known adenoma-to-CRC sequence, given the fact that these cancers appear to arise from either flat, dysplastic tissue or dysplasia-associated lesions or masses (DALMs). An important model, but by no means an absolute one, for colon carcinogenesis in IBD follows progression from an absence of dysplasia, to indefinite dysplasia, to low-grade dysplasia, on to high-grade dysplasia, and ultimately to invasive CRC. This carcinogenic process relates to the disease duration with respect to the extent of colonic involvement and may also involve primary sclerosing cholangitis. Given this knowledge of an increased risk for CRC in UC and CD, surveillance colonoscopy should initially be performed 8-10 years after onset of symptoms as opposed to diagnosis, and it should be performed 1-2 years after 8 years of disease in patients with pancolitis or after 15 years in those with left-sided colitis. A search for dysplasia of colonic mucosa with biopsies performed in all four quadrants every 10 cm throughout the colon is exceedingly important. Additional biopsies should be taken of any flat lesions, masses, or strictures. Prophylactic colectomy may then be indicated when severe dysplasia is confirmed by knowledgeable pathologists.
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PMID:Inflammatory bowel disease in Ashkenazi Jews: implications for familial colorectal cancer. 1551 46

Research efforts in the inflammatory bowel diseases have been uniquely successful in identifying genetic linkage regions likely containing susceptibility genes for Crohn's disease and ulcerative colitis. In two of these regions, definitive gene associations have been established, namely for the NOD2/CARD15 gene on chromosome 16 (IBD1) and the OCTN1/SLC22A4-OCT/SLC22A5 genes on chromosome 5q (IBD5), both conferring increased risk for developing Crohn's disease. Recently, significant gene associations have been reported for additional genes, including DLG5, MDR1, and TLR4 as well. The NOD2/CARD15 gene mutations are associated with ileal disease location and a modestly earlier age of onset compared with NOD2/CARD15 wild-type Crohn's disease patients. Future progress in the genetics of inflammatory bowel disease will likely involve systematic phenotyping, including the incorporation of clinical subtypes and novel biomarkers. The ultimate goal of genetic research in inflammatory bowel disease is to identify the earliest biologic pathways that are altered, resulting in disease pathogenesis. Identification of these key pathways will potentially highlight novel therapeutic targets.
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PMID:Advances in the genetics of inflammatory bowel disease. 1552 76

The classification of ulcerative colitis (UC), Crohn disease (CD), and indeterminate colitis (IC) as forms of inflammatory bowel disease (IBD) is based on clinical, radiological, and histological criteria. The genetic basis of IBD is well founded, and susceptibility loci have been identified on several different chromosomes. We aimed to define genotype-phenotype relationships and interactions with the IBD susceptibility gene CARD15for various IBD susceptibility loci (IBD1, IBD2, IBD5, IBD6, IBD7, and chromosome 4) by characterizing previously described peak LOD score short tandem repeat (STR) markers. The study population consisted of 484 severely affected Caucasian patients with IBD, 144 healthy controls, and 348 nonaffected first-degree relatives of IBD patients. Associations were defined with the use of population- and family-based methodology. Correction for multiple testing was performed with a method based on an experimental false discovery rate. We provide novel evidence to show that IBD2 is involved in susceptibility to IC and terminal ileal CD in this population, with overrepresentation of IBD2 STR D12S83 (GenBank Z16592.1) allele 7 (g.49_60del[CA](6)) in IC (q = 0.038, P = 0.014) and underrepresentation of allele 8 (g.51_60del[CA](5)) in terminal ileal CD (q = 0.038, P = 0.016). The association of IBD2 with IC was confirmed by family-based testing. We also provide novel evidence to show that IBD5 is involved in susceptibility to IC and colonic/ileocolonic CD in this population, with overrepresentation of IBD5 STR D5S1984 (GenBank Z52623.1) allele 5 (g.183_186del[CA](2)) in both IC (q = 0.040, P = 0.005) and colonic/ileocolonic CD (q = 0.040, P = 0.004). Evidence is also given for potential interactions between CARD15and IBD2/IBD5. Other findings include an association of IBD2 with UC, and an association of IBD1 with terminal ileal and colonic/ileocolonic CD.
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PMID:Characterization of genotype-phenotype relationships and stratification by the CARD15 variant genotype for inflammatory bowel disease susceptibility loci using multiple short tandem repeat genetic markers. 1564 11

Genomewide searches have identified about a dozen genomic regions potentially containing inflammatory bowel disease (IBD) susceptibility loci. Although some were observed in more than one genome scan or in replication studies, no one locus has been identified in all studies. This apparent lack of consistency is explained by the modest effect of most genetic loci in complex traits and by the modest power and the sampling variance of individual family-based studies. Despite these challenges, the field of IBD genetics found convincing evidence of linkage and, more recently, of genetic sequence variants that are strongly associated with disease. The first example was that of the IBD1 locus on chromosome 16, a linkage region confirmed by a large multicentre study, for which the CARD 15 gene was identified--using independent association strategies-as being a gene contributing to Crohn's disease susceptibility. Despite these advances, a number of questions still remain: (1) What is the best approach to identify the remaining IBD susceptibility loci? (2) How do we prove causality for any given gene or genetic variant? (3) How can we best use this information to obtain an understanding of the biological mechanisms underlying disease susceptibility and to identify useful markers of disease progression and response to therapy?
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PMID:Progress towards identifying inflammatory bowel disease susceptibility genes. 1566 31

Crohn's disease (CD) is a heterogeneous disorder. A genetic linkage to chromosome 16 (IBD1) has been previously observed and replicated in unrelated populations. Recently, in this region, NOD2/CARD15 has been identified as a susceptibility gene. The aim of this report is to determine whether this gene is implicated in CD in a Tunisian population. One hundred thirty patients with CD and 90 healthy individuals were genotyped for the three common NOD2 variants (C2104T in exon 4, G2722C in exon 8, and 3020insC in exon 11). Furthermore, the 11 exons of the NOD2 gene were sequenced in 20 patients with CD. Results showed that the frequency of the CARD15 variants in the Tunisian population is significantly lower than that observed in the European and American population. Direct sequencing of CARD15 did not permit us to identify a characteristic mutation in our population. No association was confirmed between CD and the NOD2 gene in our Tunisian population. Furthermore, the NOD2/CARD15 gene has a variable association with CD in different populations. These results indicate the genetic variation of CD in different ethnic groups.
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PMID:CARD15/NOD2 in a Tunisian population with Crohn's disease. 1571 50

The field of inflammatory bowel disease genetics plays a leading role in the genetics of complex traits. One of the first genetic loci for a complex trait to be identified by genome-wide linkage scans and confirmed by multiple studies was IBD1 for Crohn's disease. Shortly after this initial success, a second susceptibility locus, the IBD5 risk haplotype, was discovered and unequivocally replicated. In this review, we examine the genetics and potential functional implications of the IBD5 locus on disease susceptibility, prognosis, classification, and treatment. In addition, we discuss the challenges faced when the region identified by association contains multiple genes that are not easily separated by recombination-the primary tool of the human geneticist.
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PMID:Role of the IBD5 susceptibility locus in the inflammatory bowel diseases. 1653 25


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