Ulcerative Colitis: Thomas G

Hugot JP, Zouali H, Lesage S, Thomas G. · INSERM U434 et Fondation Jean Dausset, Paris, France. · Int J Colorectal Dis. · Pubmed #10207723 No free full text.

Abstract: Inflammatory bowel diseases (IBD) are complex disorders. While the exact etiology of these diseases remains unknown, recent progress in the epidemiology and genetics of IBD has clearly demonstrated both environmental and genetic factors to play a role in the development of the disease, and it is expected that some risk factors are common for both Crohn's disease (CD) and ulcerative colitis (UC). The environmental factor(s) are associated with the Western way of life in the second half of the twentieth century. Cigarette smoking is presently the best known environmental factor. However, the effect of tobacco is opposite in CD and UC. A familial history of IBD is the most important risk factor for developing the disease, suggesting a genetic predisposition to IBD. This hypothesis has recently been confirmed by the localization of at least two susceptibility loci on chromosomes 12 and 16. These genes seem to play a role in both CD and UC. They must now to be identified.

Zouali H, Lesage S, Merlin F, Cézard JP, Colombel JF, Belaiche J, Almer S, Tysk C, O'Morain C, Gassull M, Christensen S, Finkel Y, Modigliani R, Gower-Rousseau C, Macry J, Chamaillard M, Thomas G, Hugot JP, Anonymous00017, Anonymous00018. · Fondation Jean Dausset-CEPH, Paris, France. · Gut. · Pubmed #12477763 links to  free full text

Abstract: BACKGROUND AND AIMS: Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are complex genetic disorders. CARD15/NOD2, a member of the Ced4 superfamily which includes Apaf-1 and CARD4/NOD1, has recently been associated with genetic predisposition to CD but additional genetic factors remain to be identified. Because CARD4/NOD1 shares many structural and functional similarities with CARD15, we tested its putative role in IBD. PATIENTS AND METHODS: The 11 exons of CARD4 were screened for the presence of variants in 63 unrelated IBD patients. The only non-private genetic variation encoding for a substitution in the peptidic chain was genotyped in 381 IBD families (235 CD, 58 UC, 81 mixed, and seven indeterminate colitis families) using a polymerase chain reaction-restriction fragment length polymorphism procedure. Genotyping data were analysed by the transmission disequilibrium test. RESULTS: Five of nine sequence variations identified in the coding sequence of the gene encoded for non-conservative changes (E266K, D372N, R705Q, T787M, and T787K). Four were present in only one family. The remaining variant (E266K), which exhibited an allele frequency of 0.28, was not associated with CD, UC, or IBD. Furthermore, IBD patients carrying sequence variations in their CARD4 gene had a similar phenotype to those with a normal sequence. CONCLUSION: Our results suggest that CARD4 does not play a major role in genetic susceptibility to IBD.

Lesage S, Zouali H, Cézard JP, Colombel JF, Belaiche J, Almer S, Tysk C, O'Morain C, Gassull M, Binder V, Finkel Y, Modigliani R, Gower-Rousseau C, Macry J, Merlin F, Chamaillard M, Jannot AS, Thomas G, Hugot JP, Anonymous00210, Anonymous00211, Anonymous00212. · Fondation Jean Dausset-CEPH, 27 rue Juliette Dodu, 75010 Paris, France. · Am J Hum Genet. · Pubmed #11875755 links to  free full text

Abstract: CARD15/NOD2 encodes a protein involved in bacterial recognition by monocytes. Mutations in CARD15 have recently been found in patients with Crohn disease (CD), a chronic inflammatory condition of the digestive tract. Here, we report the mutational analyses of CARD15 in 453 patients with CD, including 166 sporadic and 287 familial cases, 159 patients with ulcerative colitis (UC), and 103 healthy control subjects. Of 67 sequence variations identified, 9 had an allele frequency >5% in patients with CD. Six of them were considered to be polymorphisms, and three (R702W, G908R, and 1007fs) were confirmed to be independently associated with susceptibility to CD. Also considered as potential disease-causing mutations (DCMs) were 27 rare additional mutations. The three main variants (R702W, G908R, and 1007fs) represented 32%, 18%, and 31%, respectively, of the total CD mutations, whereas the total of the 27 rare mutations represented 19% of DCMs. Altogether, 93% of the mutations were located in the distal third of the gene. No mutations were found to be associated with UC. In contrast, 50% of patients with CD carried at least one DCM, including 17% who had a double mutation. This observation confirmed the gene-dosage effect in CD. The patients with double-dose mutations were characterized by a younger age at onset (16.9 years vs. 19.8 years; P=.01), a more frequent stricturing phenotype (53% vs. 28%; P=.00003; odds ratio 2.92), and a less frequent colonic involvement (43% vs. 62%; P=.003; odds ratio 0.44) than were seen in those patients who had no mutation. The severity of the disease and extraintestinal manifestations were not different for any of the CARD15 genotypes. The proportion of familial and sporadic cases and the proportion of patients with smoking habits were similar in the groups of patients with CD with or without mutation. These findings provide tools for a DNA-based test of susceptibility and for genetic counseling in inflammatory bowel disease.

Hugot JP, Chamaillard M, Zouali H, Lesage S, Cézard JP, Belaiche J, Almer S, Tysk C, O'Morain CA, Gassull M, Binder V, Finkel Y, Cortot A, Modigliani R, Laurent-Puig P, Gower-Rousseau C, Macry J, Colombel JF, Sahbatou M, Thomas G. · Fondation Jean Dausset CEPH, 27 rue J. Dodu 75010 Paris, France. · Nature. · Pubmed #11385576 No free full text.

Abstract: Crohn's disease and ulcerative colitis, the two main types of chronic inflammatory bowel disease, are multifactorial conditions of unknown aetiology. A susceptibility locus for Crohn's disease has been mapped to chromosome 16. Here we have used a positional-cloning strategy, based on linkage analysis followed by linkage disequilibrium mapping, to identify three independent associations for Crohn's disease: a frameshift variant and two missense variants of NOD2, encoding a member of the Apaf-1/Ced-4 superfamily of apoptosis regulators that is expressed in monocytes. These NOD2 variants alter the structure of either the leucine-rich repeat domain of the protein or the adjacent region. NOD2 activates nuclear factor NF-kB; this activating function is regulated by the carboxy-terminal leucine-rich repeat domain, which has an inhibitory role and also acts as an intracellular receptor for components of microbial pathogens. These observations suggest that the NOD2 gene product confers susceptibility to Crohn's disease by altering the recognition of these components and/or by over-activating NF-kB in monocytes, thus documenting a molecular model for the pathogenic mechanism of Crohn's disease that can now be further investigated.

Lesage S, Zouali H, Colombel JF, Belaiche J, Cézard JP, Tysk C, Almer S, Gassull M, Binder V, Chamaillard M, Le Gall I, Thomas G, Hugot JP. · Fondation Jean Dausset/CEPH and Unité INSERM 434, 27 rue Juliette Dodu, 75010 Paris, France. · Gut. · Pubmed #11076876 links to  free full text

Abstract: BACKGROUND AND AIMS: Inflammatory bowel disease (IBD) includes ulcerative colitis and Crohn's disease, both of which are multifactorial diseases involving the interaction of genetic and environmental factors. A region on chromosome 12 centred around the marker locus D12S83 has previously been associated with IBD predisposition. The aim of the study was to investigate this genetic region in an independent panel of European families affected by Crohn's disease. METHODS: A sample of 95 families with two or more affected relatives and 75 simplex nuclear families were genotyped for 19 microsatellite loci located on chromosome 12. A search for linkage and linkage disequilibrium was performed using non-parametric two point and multipoint analyses with the Analyze and Genehunter packages. RESULTS: No evidence of linkage or linkage disequilibrium was observed for any of the marker loci, including D12S83 (p=0.35 for the two point linkage test). Multipoint linkage analysis also failed to reveal positive linkage on chromosome 12. Power calculations allowed us to reject the hypothesis that the genetic region of chromosome 12 centred on D12S83 contains a susceptibility locus with a relative risk (lambda(s)) equal to or greater than 2.0 in these families. CONCLUSION: Failure to detect linkage or linkage disequilibrium in these families suggests that the chromosome 12 locus previously reported to be associated with genetic predisposition to IBD does not play a role in all European family samples. This observation is compatible with heterogeneity in the genetic basis of susceptibility to the disease and/or exposure to various environmental factors among Caucasian families.