Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0010346 (Crohn's disease)
 21,615 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NOD2, a protein associated with susceptibility to Crohn's disease, confers responsiveness to bacterial preparations of lipopolysaccharide and peptidoglycan, but the precise moiety recognized remains elusive. Biochemical and functional analyses identified muramyl dipeptide (MurNAc-L-Ala-D-isoGln) derived from peptidoglycan as the essential structure in bacteria recognized by NOD2. Replacement of L-Ala for D-Ala or D-isoGln for L-isoGln eliminated the ability of muramyl dipeptide to stimulate NOD2, indicating stereoselective recognition. Muramyl dipeptide was recognized by NOD2 but not by TLR2 or co-expression of TLR2 with TLR1 or TLR6. NOD2 mutants associated with susceptibility to Crohn's disease were deficient in their recognition of muramyl dipeptide. Notably, peripheral blood mononuclear cells from individuals homozygous for the major disease-associated L1007fsinsC NOD2 mutation responded to lipopolysaccharide but not to synthetic muramyl dipeptide. Thus, NOD2 mediates the host response to bacterial muropeptides derived from peptidoglycan, an activity that is important for protection against Crohn's disease. Because muramyl dipeptide is the essential structure of peptidoglycan required for adjuvant activity, these results also have implications for understanding adjuvant function and effective vaccine development.
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PMID:Host recognition of bacterial muramyl dipeptide mediated through NOD2. Implications for Crohn's disease. 1251 69

Current debate focuses on the relevance of linkage disequilibrium (LD), ethnicity and underlying haplotype structure to the search for genes involved in complex disorders. The recently described association between single nucleotide polymorphisms (SNPs) of the CARD15 (NOD2) gene and Crohn's disease (CD) in populations of north-European descent provides a test case that we have subjected to detailed SNP haplotype based analyses. We examined 23 SNPs spanning 290 kb, including CARD15, in large North-European and Korean samples of patients with Crohn's disease and normal controls. In Europeans we confirmed that the three disease-associated SNPs occur independently but share a common background haplotype. This suggests a common origin and the possibility of an undiscovered more strongly predisposing mutation. Korean CD patients present a phenotype identical to the European patients and have not previously been screened for CARD15. The three disease-associated SNPs were absent and there was no evidence of association between CARD15 and CD. Consequently, the disease-associated mutations in the Europeans, which are rare, have arisen recently (after the Asian-European split). Our results highlight important issues relevant to mapping the genes that predispose to complex disorders. First, although ethnically divergent populations may present identical phenotypes they do not necessarily share the same set of predisposing genes. Second, although single-locus tests of association showed consistent association with markers throughout the gene, pair-wise LD between markers (r(2) and D') yielded very little information about actual disease-association. Third, a population comparative approach allowed refining of the marker set through the examination of shared polymorphisms and common LD-groups. This approach, in conjunction with the examination of the mutational steps in a haplotype network, allows unambiguous identification of the potentially causative mutations.
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PMID:Haplotype structure and association to Crohn's disease of CARD15 mutations in two ethnically divergent populations. 1252

Ten years ago Crohn's disease remained a highly complex disorder with an unknown aetiology and a poorly understood pathogenesis. Research in this field had repeatedly confirmed the presence of an activated intestinal immune system but the factors underlying this had not been identified. Since then, the significance of genetic susceptibility has been established and underlined by the discovery of the NOD2 gene. In turn, this has gone on to signal the importance of the innate immune system and the critical relationship between the gut flora and the intestinal mucosa. These factors, together with independent environmental triggers such as cigarette smoking, form the basis of Crohn's disease pathogenesis in the new century.
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PMID:The pathogenesis of Crohn's disease in the 21st century. 1255 95

We have previously reported strong evidence for linkage between IBD1 and Crohn's disease (CD) in Australian Crohn's disease families. Three risk alleles for Crohn's disease, (Arg702Trp (C/T), Gly908Arg (G/C) and 980fs981 (-/C), were recently identified in the CARD15/NOD2 gene on chromosome 16, implicating this as the IBD1 locus. Using a novel diagnostic PCR-RFLP, we have examined the frequency of these alleles in 205 multiplex IBD families, 107 sporadic Crohn's disease cases and 409 normal individuals. We demonstrate that the three risk alleles are more frequent in Crohn's disease, than in controls, with allelic frequencies of 0.11, 0.02 and 0.07 respectively. Heterozygosity for individual variants conferred a three-fold increase in risk for Crohn's disease while substantially higher risks were associated with being homozygous or compound heterozygous. Despite a significantly lower population allele frequency for the frameshift mutation than reported by other groups, we see a similar contribution by this allele to the risk of developing Crohn's disease. While the three risk alleles influence susceptibility to Crohn's disease in Australia, we show that these alleles do not fully explain the linkage evidence and suggest that there are very likely additional IBD1 susceptibility alleles yet to be described in Australian CD at the NOD2 locus. We also show a second linkage peak in Australian CD that provides some support for a second disease susceptibility locus on chromosome 16.
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PMID:CARD15/NOD2 risk alleles in the development of Crohn's disease in the Australian population. 1255 33

The inflammatory bowel diseases (IBD) comprise complex genetic disorders, with multiple contributing genes. Linkage studies have implicated several genomic regions as likely containing IBD susceptibility genes, with some observed uniquely in Crohn's disease (CD) or ulcerative colitis (UC), and others common to both disorders. The best replicated linkage region, IBD1, on chromosome 16q contains the CD susceptibility gene, NOD2/CARD15. NOD2/CARD15 is expressed in peripheral blood monocytes and is structurally related to the plant R proteins, which mediate host resistance to microbial pathogens. Three major coding region polymorphisms within NOD2/CARD15 have been highly associated with CD among patients of European descent. Having one copy of the risk alleles confers a 2-4-fold risk for developing CD, whereas double-dose carriage increases the risk 20-40-fold. All 3 major CD variants exhibit a deficit in NF-kappaB activation in response to bacterial components. Carriage of NOD2/CARD15 risk alleles is associated with ileal location, earlier disease onset, and stricturing phenotype. Other IBD genomic regions include IBD2 on chromosome 12q (observed more in UC), and IBD3, containing the major histocompatibility complex region. A short genomic region has been associated with CD on chromosome 5q, but the precise contributing gene is as yet unidentified. The characterization of additional IBD susceptibility genes could potentially lead to the identification of novel therapeutic agents for IBD, make possible a molecular reclassification of disease, and increase understanding of the contribution of environmental factors (notably, tobacco and the intestinal microbial milieu) to intestinal inflammation.
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PMID:The genetics of inflammatory bowel disease. 1476 96

Crohn disease (CD) exhibits a 2-4-fold increased frequency in Jews as compared with other ethnic/racial groups. Three coding variants of the NOD2/CARD15 have been reported as independent disease-predisposing mutations (DPMs), but these were found in only 30%-40% of patients with CD and could not account for all the linkage between CD and the IBD1 locus. The aim of the present study was to explore whether additional DPMs at the IBD1 locus exist in the high-risk Jewish group. Sixty-four Ashkenazi Jewish and 147 non-Jewish white families were studied. Six microsatellite markers spanning IBD1 were genotyped for linkage analysis in subgroups stratified on NOD2/CARD15 DPM status. SNPs in NOD2/CARD15 (R702W, G908R, 1007fs, and S268P) were then genotyped in family and independent case-control samples. On the basis of initial results, sequencing was done on NOD2/CARD15-translated regions in 12 Jewish individuals. Subsequently, a new NOD2/CARD15 variant was genotyped and analyzed. After excluding the influence of the three DPMs, significant linkage of IBD1 to CD in Jews remained with two peaks at D16S403 (mean allele sharing [MAS] = 0.70] and D16S411 (MAS = 0.59). Further, we observed an increased frequency of a haplotype carrying only the 268S variant in Jewish patients (OR = 3.13, P=.0023) but not in non-Jews, suggesting the existence of a Jewish-specific additional disease-predisposing factor on this haplotype. Sequencing of this haplotype revealed a new variant (IVS8+158; JW1). The 268S-JW1 combination exhibited a further increased risk (OR = 5.75, P=.0005) and the highest population-attributable risk (15.1%) for CD among reported DPMs in Jews. In Ashkenazi Jews, unrecognized population-specific predisposing factor(s) exist on the 268S-JW1 haplotype at the IBD1 locus. This factor may contribute to the higher risk for CD in Ashkenazi Jews as compared with non-Jews.
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PMID:A novel NOD2/CARD15 haplotype conferring risk for Crohn disease in Ashkenazi Jews. 1476 95

Epidemiological and genetic linkage studies have indicated a strong genetic basis for development of inflammatory bowel disease (IBD) which was recently supported by discovery of the Crohn's disease (CD) susceptibility gene termed NOD2/CARD15. We carried out a genome-wide linkage study in Finnish IBD families, providing a particular advantage to map susceptibility genes for ulcerative colitis (UC) within a genetic isolate. Initially, 92 IBD families with 138 affected sib-pairs (ASPs), were genotyped for 429 markers spaced at approximately 10 cM intervals. Next, the loci on chromosomes 2p13-11, 11p12-q13, and 12p13-12 were high-density mapped in the extended family cohort of 130 families with 173 ASPs. In this study, the most significant lod scores were observed for the UC families on chromosome 2p11 (D2S2333), in the vicinity of the REG gene cluster which is strikingly overexpressed in the IBD mucosa. The maximum two-point lod score was 3.34 (dominant model), and the corresponding NPL score 2.61. For UC, the second highest two-point NPL score of 2.00 was observed at proximal 12p13, where also some evidence for linkage disequilibrium emerged (P=0.07 and P=0.007 for the basic and extended IBD cohorts, respectively). The highest two-point NPL score for the CD families was 2.34 at D12S78 (12q23) with significant evidence for linkage disequilibrium (P=0.004), and for the mixed (MX) families 2.07 at D4S406 near the linkage peak reported previously. This study confirmed several of the IBD loci that have previously been reported and gives evidence for new IBD loci on chromosomes 2p11, 11p12-q13, 12p13-12, 12q23, and 19q13.
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PMID:Genome-wide search in Finnish families with inflammatory bowel disease provides evidence for novel susceptibility loci. 1263 58

Linkage of IBD to the pericentromeric region of chromosome 16 has been widely confirmed by analyses of multiple populations. The NOD2 gene is located in the peak region of linkage on chromosome 16 and thought to be involved in the activation of nuclear factor (NF) kappaB in response to bacterial components. Mutations in the NOD2 gene are found to be strongly associated with susceptibility to Crohn's disease (CD). A total of 65 Irish CD families were genotyped to determine if NOD2 mutations conferred susceptibility to CD and the prevalence of these mutations in sporadic and familial forms of the disease. The Irish population is relatively homogenous and thus may provide advantages in genetic studies of complex diseases. We confirmed the IBD1 locus as a susceptibility locus for IBD within the Irish population by linkage analysis followed by linkage disequilibrium studies. No significant evidence of linkage was observed to the previously identified regions on chromosomes 1, 12 and 14. In all, 131 CD affected families were then genotyped for seven of the previously published NOD2 single-nucleotide polymorphisms (SNPs). Allelic transmission distortion was investigated using the pedigree disequilibrium test (PDT). SNP13 (3020insC) was found to be associated with CD (P=0.0186). Patients who possessed a rare allele of SNP8, 12 or 13 presented earlier when compared to patients without rare variants (mean age, 20.1 vs 24 years, P=0.011) and the rare allele of SNP13 was observed to be predominantly linked to ileal disease (P=0.02). This report confirms the importance of NOD2 as a susceptibility gene for CD within the Irish population.
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PMID:Association of NOD2 with Crohn's disease in a homogenous Irish population. 1267 78

Our rapidly expanding understanding of the genetics of inflammatory bowel disease (IBD) has led to important clinical applications. It is becoming apparent that genes help determine the clinical phenotype, intestinal and extraintestinal complications, response to treatment, and drug toxicities in these disorders. For example, NOD2/CARD15 mutations are associated with ileal Crohn's disease, possibly with a fibrosing/obstructing phenotype, but do not influence responses to infliximab treatment. Similarly, certain human leukocyte antigen (HLA) haplotypes are associated with aggressive, extensive ulcerative colitis and strongly influence extraintestinal manifestations of IBD, including uveitis and various forms of arthritis. Expression of the glucocorticoid receptor b determines the clinical response to corticosteroids, whereas genetically regulated levels of enzymes metabolizing 6-mercaptopurine/azathioprine may determine clinical responses and toxicities to these important immunosuppressive agents. Once we have a more sophisticated understanding of the mechanisms of genetic defects in IBD, it may be feasible to restore physiologic function to prevent the onset of disease in susceptible individuals. However, because we do not have the ability to prevent disease at the present time, it is premature to screen offspring and first-degree relatives of IBD patients for the NOD2/CARD15 genotype. One can anticipate that it will become feasible to prospectively determine a patient's genotype and to individualize a drug regimen, leading to highly effective, safe treatments for IBD patients on a rational, rather than empiric, basis.
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PMID:Clinical applications of advances in the genetics of IBD. 1268 84

Inflammatory bowel disease (IBD) clusters within families, suggesting a genetic component to disease pathogenesis. Studies have identified a gene on chromosome 16cen that confers susceptibility to Crohn's disease. The affected gene codes for the NOD2/CARD15 protein, which is involved in the immune system's response to bacterial infection. Multiple mutations have been identified, three of which have been shown to be independently associated with Crohn's disease-arg702trp, gly908arg, and leu1007fsinsC. Taken together, these three variants confer a 15%-20% attributable population risk among cases of familial Crohn's disease, with decreased contribution among the more common sporadic cases of the disease. The presence of an NOD2 risk allele has been shown to be associated with ilial disease as well as an earlier age of disease onset. Further studies are needed to clarify the relationship between IBD genotype and disease behavior.
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PMID:Significant role of genetics in IBD: the NOD2 gene. 1268 85


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