Genetic factors conferring an increased susceptibility to develop Crohn's disease also influence disease phenotype: results from the IBDchip European Project.

OBJECTIVE: Through genome-wide association scans and meta-analyses thereof, over 70 genetic loci (Crohn's disease (CD) single nucleotide polymorphisms (SNPs)) are significantly associated with CD. We aimed to investigate the influence of CD-SNPs and basic patient characteristics on CD clinical course, and develop statistical models to predict CD clinical course. DESIGN: This retrospective study included 1528 patients with CD with more than 10 years of follow-up from eight European referral hospitals. CD outcomes of interest were ileal (L1), colonic (L2) and ileocolonic disease location (L3); stenosing (B2) or penetrating behaviour (B3); perianal disease; extraintestinal manifestations; and bowel resection. A complicated disease course was defined as stenosing or penetrating behaviour, perianal disease and/or bowel resection. Association between CD-SNPs or patient characteristics and specified outcomes was studied. RESULTS: Several CD-SNPs and clinical characteristics were statistically associated with outcomes of interest. The NOD2 gene was the most important genetic factor, being an independent predictive factor for ileal location (p=2.02 × 10(-06), OR=1.90), stenosing (p=3.16 × 10(-06), OR=1.82) and penetrating (p=1.26 × 10(-02), OR=1.25) CD behaviours, and need for surgery (p=2.28 × e-05, OR=1.73), and as such was also the strongest factor associated with a complicated disease course (p=6.86 × 10(-06), OR=2.96). Immunomodulator (azathioprine/6-mercaptopurine and methotrexate) use within 3 years after diagnosis led to a reduction in bowel stenoses (p=1.48 × 10(-06), OR=0.35) and surgical rate (p=1.71 × 10(-07), OR=0.34). Association between each outcome and genetic scores, created using significant SNPs in the univariate analysis, revealed large differences in the probability of developing fistulising disease (IL23R, LOC441108, PRDM1, NOD2; p=9.64e-4, HR=1.43), need for surgery (IRGM, TNFSF15, C13ORF31, NOD2; p=7.12 × 10(-03), HR=1.35), and stenosing disease (NOD2, JAK2, ATG16L1; p=3.01 × 10(-02), HR=1.29) among patients with low and high score. CONCLUSIONS: This large multicentre cohort study has found several genetic and clinical factors influencing the clinical course of CD. NOD2 and early immunomodulator use are the clinically most meaningful predictors for its clinical course.

Subclinical mucosal inflammation in diarrhea-predominant irritable bowel syndrome (IBS) in a tropical setting.

BACKGROUND AND AIMS: There is evidence for low-grade inflammation in the pathophysiology of post-infectious irritable bowel syndrome (IBS). We assessed the degree of subclinical intestinal mucosal inflammation in diarrhea-predominant IBS (IBS-D) in a tropical setting. MATERIAL AND METHODS: In a prospective study over 1 year, we investigated 49 patients with IBS-D (cases; median age 34 years (range 18-59); M:F 36:13), diagnosed on Rome III criteria. 14 individuals with a family history of colon cancer (median age 46.5 years (range 23-56); M:F 6:8) were selected as controls. Stools of cases and controls were tested for calprotectin. During colonoileoscopy, serial biopsies were obtained. Mucosal mast cells, neutrophils, eosinophils and lymphocytes/plasma cell infiltrate were quantified. Tissue expression of IL-8 and IL-10 was assessed in biopsies by semi-quantitative RT-PCR. RESULTS: A history suggestive of an episode of infectious diarrhea (ID) was present in 16/49 cases and 0/14 controls (p = 0.013). In cases, there were significantly more mucosal mast cells in the ileum and all segments of colon and significantly more eosinophils in the cecum. Tissue expression of IL-8 was significantly higher and IL-10 significantly lower in cases compared with controls (target/standard cDNA ratio, median (range) IL-8: 1.25 (0.75-2) vs. 0.85 (0.63-1.3), p < 0.0001, Mann-Whitney U test; IL-10: 0.33 (0-0.63) vs. 0.55 (0.5-0.7), p < 0.0001). There was a significant inverse correlation between IL-8 and IL-10 expression (Pearson correlation, (-) 0.509; p < 0.01). CONCLUSION: There was evidence of subclinical intestinal mucosal inflammation in patients with IBS-D. The finding of increased eosinophils is novel, and may be of special relevance to IBS-D in the tropics.

The IL-23/IL-17 pathway in inflammatory bowel disease.

The etiology of inflammatory bowel disease is unknown but available evidence suggests that a deregulated immune response towards the commensal bacterial flora is responsible for intestinal inflammation in genetically predisposed individuals. IL-23 promotes expansion and maintenance of Th17 cells, which secrete the proinflammatory cytokine IL-17 and have been implicated in the pathogenesis of many chronic inflammatory disorders. Recent studies have shown that IL-23 also acts on cells of the innate immune system that can contribute to inflammatory cytokine production and tissue inflammation. A role for the IL-23/IL-17 pathway in the pathogenesis of chronic intestinal inflammation in inflammatory bowel disease has emerged from both animal and human studies. Here we aim to review the recent advances in this rapidly moving field.

Comprehensive, quantitative mapping of T cell epitopes in gluten in celiac disease.

Celiac disease is a genetic condition that results in a debilitating immune reaction in the gut to antigens in grain. The antigenic peptides recognized by the T cells that cause this disease are incompletely defined. Our understanding of the epitopes of pathogenic CD4(+ )T cells is based primarily on responses shown by intestinal T-cells in vitro to hydrolysates or polypeptides of gluten, the causative antigen. A protease-resistant 33-amino acid peptide from wheat alpha-gliadin is the immunodominant antigen, but little is known about the spectrum of T cell epitopes in rye and barley or the hierarchy of immunodominance and consistency of recognition of T-cell epitopes in vivo. We induced polyclonal gluten-specific T cells in the peripheral blood of celiac patients by feeding them cereal and performed a comprehensive, unbiased analysis of responses to all celiac toxic prolamins, a class of plant storage protein. The peptides that stimulated T cells were the same among patients who ate the same cereal, but were different after wheat, barley and rye ingestion. Unexpectedly, a sequence from omega-gliadin (wheat) and C-hordein (barley) but not alpha-gliadin was immunodominant regardless of the grain consumed. Furthermore, T cells specific for just three peptides accounted for the majority of gluten-specific T cells, and their recognition of gluten peptides was highly redundant. Our findings show that pathogenic T cells in celiac disease show limited diversity, and therefore suggest that peptide-based therapeutics for this disease and potentially other strongly HLA-restricted immune diseases should be possible.

Genome-wide association study of ulcerative colitis identifies three new susceptibility loci, including the HNF4A region.

Ulcerative colitis is a common form of inflammatory bowel disease with a complex etiology. As part of the Wellcome Trust Case Control Consortium 2, we performed a genome-wide association scan for ulcerative colitis in 2,361 cases and 5,417 controls. Loci showing evidence of association at P < 1 x 10(-5) were followed up by genotyping in an independent set of 2,321 cases and 4,818 controls. We find genome-wide significant evidence of association at three new loci, each containing at least one biologically relevant candidate gene, on chromosomes 20q13 (HNF4A; P = 3.2 x 10(-17)), 16q22 (CDH1 and CDH3; P = 2.8 x 10(-8)) and 7q31 (LAMB1; P = 3.0 x 10(-8)). Of note, CDH1 has recently been associated with susceptibility to colorectal cancer, an established complication of longstanding ulcerative colitis. The new associations suggest that changes in the integrity of the intestinal epithelial barrier may contribute to the pathogenesis of ulcerative colitis.

Contribution of histological, serological, and genetic factors to the clinical heterogeneity of adult-onset coeliac disease.

OBJECTIVE: Although the factors predisposing to coeliac disease (CD) are largely understood, it remains unclear what determines the clinical heterogeneity of the disease. The aim of this study was to explore the contribution of histological, serological, and genetic factors to disease presentation. MATERIAL AND METHODS: The study was designed as a retrospective chart review of 384 unrelated Caucasian patients diagnosed with CD after the age of 16 at a single UK centre. RESULTS: We found that 8.8% of IgA-competent CD patients were endomysial antibody (EMA)-negative. Compared with the EMA-positive group, EMA-negative CD patients had a lower prevalence of iron deficiency (52.0% versus 72.6%, p=0.03) and Marsh IIIb-c lesions (66.7% versus 85.3%, p=0.03). Histological severity at diagnosis correlated with anaemia (p<0.01), folate deficiency (p<0.01), and iron deficiency (p=0.05), but no other laboratory or clinical features. Compared with human leucocyte antigen (HLA)-DQ2.5-positive patients, those carrying HLA-DQ2.2 were similar in terms of all the characteristics we considered, whereas those carrying HLA-DQ8 had a lower frequency of EMA positivity (62.5% versus 92.6%, p<0.01). The proportion of EMA-positive patients increased with frequency of the HLA-DQB1*0201 allele (76.7% versus 92.3% versus 96.4% for 0 versus 1 versus 2 alleles, p<0.01); no other evidence of a gene-dose effect of HLA-DQB1*0201 was observed. CONCLUSIONS: Histological severity at diagnosis of CD is associated with anaemia and some micronutrient deficiencies, but no other clinical features. The proportion of EMA-positive patients is higher amongst those carrying HLA-DQ2 than in those carrying HLA-DQ8, and is highest in HLA-DQ2 homozygotes. We found no correlation between frequency of the HLA-DQ alleles encoding HLA-DQ2.5 and CD severity.

Characterization of inflammatory bowel disease with urinary metabolic profiling.

OBJECTIVES: Distinguishing between the inflammatory bowel disease (IBD), Crohn's disease (CD), and ulcerative colitis (UC) is important for both management and prognostic reasons. Discrimination using noninvasive techniques could be an adjunct to conventional diagnostics. Differences have been shown between the intestinal microbiota of CD and UC patients and controls; the gut bacteria influence specific urinary metabolites that are quantifiable using proton high-resolution nuclear magnetic resonance (NMR) spectroscopy. This study tested the hypothesis that such metabolites differ between IBD and control cohorts, and that using multivariate pattern-recognition analysis, the cohorts could be distinguished by urine NMR spectroscopy. METHODS: NMR spectra were acquired from urine samples of 206 Caucasian subjects (86 CD patients, 60 UC patients, and 60 healthy controls). Longitudinal samples were collected from 75 individuals. NMR resonances specific for metabolites influenced by the gut microbes were studied, including hippurate, formate, and 4-cresol sulfate. Multivariate analysis of all urinary metabolites involved principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA). RESULTS: Hippurate levels were lowest in CD patients and differed significantly between the three cohorts (P<0.0001). Formate levels were higher and 4-cresol sulfate levels lower in CD patients than in UC patients or controls (P=0.0005 and P=0.0002, respectively). PCA revealed clustering of the groups; PLS-DA modeling was able to distinguish the cohorts. These results were independent of medication and diet and were reproducible in the longitudinal cohort. CONCLUSIONS: Specific urinary metabolites related to gut microbial metabolism differ between CD patients, UC patients, and controls. The emerging technique of urinary metabolic profiling with multivariate analysis was able to distinguish these cohorts.

Association between genetic variants in myosin IXB and Crohn's disease.

BACKGROUND: Genetic variation in myosin IXB (MYO9B) was found to be associated with ulcerative colitis (UC) in a recent collaborative study. A nonsynonymous single nucleotide polymorphism (SNP) rs1545620 at the 3' end of the gene was found to be significantly associated with UC and weakly associated with Crohn's disease (CD). The aim of our current study was to replicate these findings in an independent UC cohort and to investigate association with CD. We also investigated subphenotype association and interactions with CARD15, IL23R, ATG16L1, and the IBD5 risk haplotype. METHODS: In all, 652 CD patients, 650 UC patients, and 1190 controls were genotyped for 8 MYO9B SNPs. Haplotype testing, epistasis testing with known polymorphisms, and subphenotype analysis were performed. RESULTS: An intronic SNP rs2305767 in the MYO9B gene was associated with inflammatory bowel disease (IBD) overall (corrected P-value 0.002, odds ratio [OR] 0.76, 95% confidence interval [CI] 0.67-0.86). On individual disease analysis an association was found with CD (corrected P-value 0.001, OR 0.62, 95% CI 0.53-0.73) but not with UC. Analysis of the common MYO9B haplotypes showed significant association for CD and UC alone and IBD overall. No subphenotypic association was found. These data support an association between CD and SNPs in MYO9B independent of the established effects of SNPs in CARD15, IL23R, ATG16L1, and the IBD5 haplotype. There was no evidence of epistasis between SNPs in MYO9B and these established genes. CONCLUSIONS: MYO9B variants may be involved in IBD pathogenesis.

Investigation of Crohn's disease risk loci in ulcerative colitis further defines their molecular relationship.

BACKGROUND & AIMS: Identifying shared and disease-specific susceptibility loci for Crohn's disease (CD) and ulcerative colitis (UC) would help define the biologic relationship between the inflammatory bowel diseases. More than 30 CD susceptibility loci have been identified. These represent important candidate susceptibility loci for UC. Loci discovered by the index genome scans in CD have previously been tested for association with UC, but those identified in the recent meta-analysis await such investigation. Furthermore, the recently identified UC locus at ECM1 requires formal testing for association with CD. METHODS: We analyzed 45 single nucleotide polymorphisms, tagging 29 of the loci recently associated with CD in 2527 UC cases and 4070 population controls. We also genotyped the UC-associated ECM1 variant rs11205387 in 1560 CD patients and 3028 controls. RESULTS: Nine regions showed association with UC at a threshold corrected for the 29 loci tested (P < .0017). The strongest association (P = 4.13 x 10(-8); odds ratio = 1.27) was identified with a 170-kilobase region on chromosome 1q32 that contains 3 genes. We also found association with JAK2 and replicated a recently reported association with STAT3, further implicating the role of this signaling pathway in inflammatory bowel disease. Additional novel UC susceptibility genes were LYRM4 and CDKAL1. Twenty of the loci were not associated with UC, and several appear to be specific to CD. ECM1 variation was not associated with CD. CONCLUSIONS: Collectively, these data help define the genetic relationship between CD and UC and characterize common, as well as disease-specific mechanisms of pathogenesis.

Pneumococcal infection in patients with coeliac disease.

OBJECTIVES: Some patients with coeliac disease are hyposplenic. Splenectomy is a risk factor for pneumococcal infection. Our objective was to determine the risk of invasive pneumococcal disease - septicaemia, pneumonia or meningitis - in patients with coeliac disease. METHODS: We analysed routinely collected, linked statistical records of hospital admission to study the risk of pneumococcal infection in patients with coeliac disease, in patients who underwent splenectomy and in a comparison cohort. The main outcome measure was the rate ratio for pneumococcal infection in the coeliac and splenectomized cohorts, compared with the comparison cohort. We undertook the study using linked records in two temporally and geographically distinct populations: the Oxford region (1963-1999) and the whole of England (1998-2003). RESULTS: The rate ratio of pneumococcal infection in patients with coeliac disease was 2.06 (95% confidence interval, 1.27-3.15) in the Oxford population and 1.61 (1.36-1.90) in England as a whole. As a comparison, the rate ratios in splenectomized patients were 3.40 (2.44-4.60) and 3.32 (2.80-3.90) in the Oxford and England populations, respectively. The increased rate ratio in coeliac patients persisted beyond the first year after diagnosis of the coeliac disease. The period covered by the Oxford study was mainly before the widespread availability of pneumococcal vaccination; but the availability of pneumococcal vaccine was widespread during the time of the English study. CONCLUSION: Some patients with coeliac disease have an elevated risk of invasive pneumococcal disease.

Genetic determinants of ulcerative colitis include the ECM1 locus and five loci implicated in Crohn's disease.

We report results of a nonsynonymous SNP scan for ulcerative colitis and identify a previously unknown susceptibility locus at ECM1. We also show that several risk loci are common to ulcerative colitis and Crohn's disease (IL23R, IL12B, HLA, NKX2-3 and MST1), whereas autophagy genes ATG16L1 and IRGM, along with NOD2 (also known as CARD15), are specific for Crohn's disease. These data provide the first detailed illustration of the genetic relationship between these common inflammatory bowel diseases.

Two-stage candidate gene study of chromosome 3p demonstrates an association between nonsynonymous variants in the MST1R gene and Crohn's disease.

BACKGROUND: Genomewide linkage studies identified chromosome 3p21 as an IBD locus. Genomewide association studies have supported this locus and the Wellcome Trust Case Control Consortium (WTCCC) study narrowed it to a 0.6 Mb region. Our objectives were to perform a 2-stage candidate gene association study of the 3p locus and to identify linkage disequilibrium (LD) between significant single-nucleotide polymorphisms (SNPs) and an Oxfordshire subset (n = 282) of the WTCCC as well as the HapMap SNPs. METHODS: A total of 197 SNPs in 53 genes from the 3p locus were genotyped on the Illumina platform in a screening cohort of 469 Crohn's disease (CD) patients and 461 controls. Significant associations were then genotyped on the iPLEX platform in the original as well as a second cohort of 139 CD patients, 670 ulcerative colitis (UC) patients, and 1131 controls. All cases and controls were Caucasian and from the Oxfordshire region of the UK. RESULTS: An intronic SNP rs1128535 in the TRAIP gene was associated with CD in the screening and validation cohorts (combined [n = 608] P = 0.0004 [corrected 0.002], odds ratio [OR] 0.77, 95% confidence interval [CI], 0.67-0.89]). No association was seen for UC. Epistasis was seen with the common CARD15 mutations (P = 0.00003 [corrected 0.0006], OR 0.48, 95% CI, 0.34-0.68). No LD was demonstrated with the WTCCC SNPs. Strong LD was demonstrated with 2 nonsynonymous HapMap SNPs in the MST1R gene in an adjacent LD block to the peak WTCCC association, suggesting a distinct association signal. CONCLUSIONS: The LD with these functional MST1R variants implicate this gene as having a possible role in CD pathogenesis.

Indeterminate colitis: a review of the concept--what's in a name?

The precise diagnosis of colitis cannot always be established with the available diagnostic tools. The subgroup of patients with an uncertain diagnosis has been classified as "indeterminate colitis" (IC). The definition of "indeterminate," however, has changed over the years. Originally, IC was proposed by pathologists for colectomy specimens, usually from patients operated on for severe colitis, showing overlapping features of ulcerative colitis (UC) and Crohn's disease (CD). Later, the same terminology was used for patients showing no clear clinical, endoscopic, histologic, and other features allowing a diagnosis of either UC or CD. Therefore, it is difficult to compare different studies. An International Organization of Inflammatory Bowel Diseases (IOIBD) working party confirmed 1) the ambiguous nature of the term, and 2) proposes an updated classification for the category of patients with an unclear diagnosis. According to this, the term IBD unclassified (IBDU) is confirmed, as suggested by the Montreal Working Party 2005 for patients with clinically chronic colitis, that clearly have IBD but when definitive features of CD or UC are absent. In resected specimens the term "colitis of uncertain type or etiology" (CUTE) is preferred. It is accepted that most of the time this may have a prefix, such as severe, chronic. The classification of IBD varies when based only on biopsies rather than on a colectomy specimen. The vast majority of these have severe colitis. For those that cannot bear to abandon the highly ambiguous term IC, if it is used at all, this is where it can be used parenthetically.

Sequence variants in the autophagy gene IRGM and multiple other replicating loci contribute to Crohn's disease susceptibility.

A genome-wide association scan in individuals with Crohn's disease by the Wellcome Trust Case Control Consortium detected strong association at four novel loci. We tested 37 SNPs from these and other loci for association in an independent case-control sample. We obtained replication for the autophagy-inducing IRGM gene on chromosome 5q33.1 (replication P = 6.6 x 10(-4), combined P = 2.1 x 10(-10)) and for nine other loci, including NKX2-3, PTPN2 and gene deserts on chromosomes 1q and 5p13.

Contribution of the novel inflammatory bowel disease gene IL23R to disease susceptibility and phenotype.

BACKGROUND: A North American genome-wide single nucleotide polymorphism (SNP) association study identified IL23R as a novel inflammatory bowel disease (IBD) susceptibility gene. Association was reported with multiple risk variants in the centromeric portion of IL23R in 3 large independent cohorts. The aims of this study were to replicate the association of IL23R with Crohn's disease (CD), examine subphenotype relationships, and look for evidence of epistasis with the known CD susceptibility gene CARD15 and susceptibility haplotype IBD5 in a large collection of CD patients. We further investigated the relationship between IL23R and ulcerative colitis (UC). METHODS: In all, 604 CD and 647 UC patients who had been rigorously phenotyped and who had been recruited from a single UK center were used in this study. Controls were either spouses of patients (141) or were recruited from well-person clinics (993). Eight SNPs were genotyped using MassArray (Sequenom). All 8 SNPs genotyped were significantly associated with CD. RESULTS: The association with the nonsynonymous SNP rs11209026 was confirmed (P=6.65x10(-6), odds ratio [OR], 0.43, 95% confidence interval [CI]: 0.29-0.64). The most significant SNP in our study was rs7517847 (P=4.9x10(-9), OR 0.65, 0.56-0.75), which is statistically independent of rs11209026. Preliminary evidence suggests an epistatic interaction with the IBD5 risk haplotype. The effects of mutations in this IL23R appear weaker in UC (P=0.008, OR 0.63, 0.45-0.89 and 0.005 OR, 0.81, 0.71-0.94, respectively). No subphenotype associations were identified. CONCLUSIONS: We confirmed the findings that IL23R is a susceptibility gene for IBD with suggestive epistasis with the IBD5 locus in the CD population.

Confirmation of the role of ATG16L1 as a Crohn's disease susceptibility gene.

BACKGROUND: A German genome-wide nonsynonymous single nucleotide polymorphism (nsSNP) association study identified ATG16L1 as a Crohn's disease (CD) susceptibility gene. The association appeared to be confined to the nsSNP rs2,241,880 and was confirmed in 2 German independent case-control collections (combined P = 4.0 x 10(-8), odds ratio [OR] 1.45; 95% confidence interval [CI]: 1.21-1.74), a CD transmission disequilibrium test (TDT) collection, and an independent UK cohort. A weak statistical interaction with CARD15 was demonstrated. No association with ulcerative colitis (UC) was demonstrated. The aims of the study were to replicate the association with CD, examine subphenotype associations and statistical interactions with CARD15, IL23R, and the IBD5 risk haplotype, as well as explore the association with UC. METHODS: The study included 645 CD and 676 UC rigorously phenotyped patients recruited from a single UK center. Unaffected controls comprised either spouses of patients (141) or individuals recruited from well-person clinics (1,049). The nsSNP rs2,241,880 was genotyped using MassArray (Sequenom). RESULTS: A strong association with CD was demonstrated (P = 2.33 x 10(-7), OR 1.45 [1.25-1.67]), but no significant association was demonstrated with any subphenotype. We failed to replicate the reported interaction between rs2,241,880 and the CARD15 low-risk haplotypes dd and Dd. No significant statistical interaction with the 3 known CD susceptibility genes was seen. No association with UC susceptibility (P = 0.37, OR 1.06 [0.93-1.22]), or any UC subphenotype was identified. CONCLUSIONS: We confirmed the findings that ATG16L1 is a CD susceptibility gene and found no evidence of interaction with CARD15, IL23R, or IBD5.

Prevalence of CARD15/NOD2 mutations in Caucasian healthy people.

BACKGROUND: Crohn's disease (CD) has been associated with CARD15/NOD2 mutations in Caucasians. The R702W, G908R, and 1007fs mutations represent 82% of the mutated chromosomes. The relative risk of developing CD in homozygous or compound heterozygous people has been estimated as between 10 and 40 times that of the general population. This high risk may support the opinion that CARD15/NOD2 variants are strong CD risk factors at the individual and population levels. SUBJECTS AND METHODS: The allele and genotype frequencies were calculated for the R702W, G908R, and 1007fs mutations in 3,575 Caucasian healthy controls recruited by 15 groups distributed on three continents. Geographic homogeneity was tested and the observed proportion of double mutants was compared with the expected value using chi2 tests. RESULTS: The allele frequencies of the R702W, G908R, and 1007fs mutations were 4.3% (3.6-4.9), 1.2% (0.8-1.6), and 2.3% (1.8-2.8), respectively, with large geographic fluctuations of the G908R, 1007fs, and wild-type alleles (P<0.0001). At the population level, no simple relationship was observed between mutation frequencies and the disease incidences in the studied populations. At the individual level, no significant deficit of double-dose mutation carriers among healthy controls was found, providing strong evidence that the penetrances of the most at-risk genotypes are low. CONCLUSION: Altogether, these data confirm that CARD15/NOD2 acts in interaction with other unknown risk cofactors.

TUCAN (CARD8) genetic variants and inflammatory bowel disease.

BACKGROUND & AIMS: The identification of the association between Crohn's disease (CD) and NOD2 (CARD15) confirmed both the heritability of CD and highlighted the role of the nuclear factor kappaB (NFkappaB) pathway in disease pathogenesis. Other susceptibility loci exist. TUCAN (CARD8) is located beneath a CD peak of linkage on chromosome 19q. TUCAN is expressed in the gut and is a negative regulator of NFkappaB, making it an excellent candidate gene for gastrointestinal inflammation. METHODS: Ten single nucleotide polymorphisms (SNP) across TUCAN were genotyped in 365 controls, 372 patients with CD, and 373 patients with ulcerative colitis. A diagnostic panel for CD was constructed using smoking status and TUCAN, NOD2, IBD5, NOD1, and TNFSF15 data. RESULTS: We demonstrate significant association between a TUCAN SNP and CD (OR 1.35, P = .0083). The association was more pronounced with disease affecting sites other than the colon (odds ratio, 1.52) and NOD2-negative CD (odds ratio, 1.50). Combination of these data with smoking and NOD2, IBD5, NOD1, and TNFSF15 status demonstrated very strong associations with CD and high sensitivities (96.3%), specificities (99.4%), and likelihood ratios (12.8) for CD, although further work will be needed before this model can be translated into direct clinical utility. CONCLUSIONS: We have shown an association between a likely functional polymorphism in TUCAN and CD. The combination of these data in a genetic panel suggests that clinicians may soon be able to translate genetic advances into direct benefits for patients.

Fistulating anal Crohn's disease: results of combined surgical and infliximab treatment.

INTRODUCTION: Infliximab is a monoclonal antibody against tumor necrosis factor-alpha, which has been shown to be effective in fistulating Crohn's disease. The safety of infliximab in patients with potential perianal sepsis is uncertain. This study was designed to assess the safety and outcome of infliximab therapy combined with surgery for patients with fistulating anal Crohn's disease. METHODS: All patients receiving infliximab for fistulating anal Crohn's disease between 2000 and 2004 were studied. Patients' demographics, clinical findings, magnetic resonance imaging, and examination under anesthesia were recorded. Perianal Crohn's disease activity index before and 8 to 12 weeks after three infusions of infliximab (5 mg/kg) were recorded. Routine policy was to insert drainage seton sutures at the time of preinfliximab examination under anesthesia and then remove it after the second infusion. Complications of treatment and outcome at the last clinic follow-up were recorded. RESULTS: Twenty-two patients underwent infliximab treatment (6 males; median age, 35 (range, 16-60) years). Twenty-one patients had preinfliximab examination under anesthesia: 12 required abscess drainage; 17 had at least one drainage seton suture inserted. Fourteen patients underwent pretreatment magnetic resonance imaging to identify clinically occult collections. All but one patient were established on immunomodulator therapy before infliximab treatment. Perianal Crohn's disease activity index improved significantly after infliximab infusion (preinfusion: median, 11, range, 8-17; postinfusion: median, 8, range, 5-16; P<0.001). There were no serious complications of infliximab treatment. At median follow-up of 21 (range, 4-31) months, only four patients achieved sustained fistula healing. Five patients have required defunctioning or proctectomy. Four patients have required repeated infusions of infliximab. CONCLUSIONS: Infliximab therapy in combination with examination under anesthesia/seton drainage is a safe and effective short-term treatment for fistulating anal Crohn's disease. Long-term fistula healing rates are low.

Therapy Insight: pyoderma gangrenosum-old disease, new management.

Well-designed studies that help guide physicians to apply the optimal therapeutic strategy for the management of pyoderma gangrenosum are lacking in the literature. A multidisciplinary approach is paramount for the effective management of this condition, with close involvement of a wound-care specialist and a microbiologist. Treatment should be stepwise in nature. Local wound care, avoidance of trauma and the application of local steroid or tacrolimus ointment are the first-line treatments. Steroid therapy is the most widely published effective therapy for achieving resolution of pyoderma gangrenosum, although there is growing evidence for the efficacy of infliximab in refractory cases. Other therapies such as dapsone and clofazamine should be left as third-line agents for refractory pyoderma gangrenosum, while novel treatments such as granulocyte apheresis should only be used under trial conditions, to gain an objective evaluation of their efficacy. This article reviews the published treatment strategies in current use, and aims to guide the effective management of pyoderma gangrenosum.