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Background: In recent years, an increasing prevalence of obesity in inflammatory bowel disease (IBD) has been observed. However, only a few studies have focused on the impact of overweight and obesity on IBD-related disability., Aims: To identify the factors associated with obese and overweight patients with IBD, including IBD-related disability., Patients and Methods: In this cross-sectional study, we included 1704 consecutive patients with IBD in 42 centres affiliated with the Groupe d'Etude Therapeutique des Affections Inflammatoires du tube Digestif (GETAID) using a 4-page questionnaire. Factors associated with obesity and overweight were assessed using univariate and multivariate analyses (odds ratios (ORs) are provided with 95% confidence intervals)., Results: The prevalence rates of overweight and obesity were 24.1% and 12.2%, respectively. Multivariable analyses were stratified by age, sex, type of IBD, clinical remission and age at diagnosis of IBD. Overweight was significantly associated with male sex (OR = 0.52, 95% CI [0.39-0.68], p < 0.001), age (OR = 1.02, 95% CI [1.01-1.03], p < 0.001) and body image subscore (OR = 1.15, 95% CI [1.10-1.20], p < 0.001) (Table 2). Obesity was significantly associated with age (OR = 1.03, 95% CI [1.02-1.04], p < 0.001), joint pain subscore (OR = 1.08, 95% CI [1.02-1.14], p < 0.001) and body image subscore (OR = 1.25, 95% CI [1.19-1.32], p < 0.001) (Table 3)., Conclusion: The increasing prevalence of overweight and obesity in patients with IBD is associated with age and poorer body image. A holistic approach to IBD patient care should be encouraged to improve IBD-related disability and to prevent rheumatological and cardiovascular complications., Competing Interests: Declaration of Competing Interest Yoram Bouhnik received lecture and consulting fees from Abbvie, Biogaran, Boehringer-Ingelheim, CTMA, Ferring, Gilead, Hospira, ICON, Inception IBD, Janssen, Lilly, Mayoli Spindler, Merck, MSD, Norgine, Pfizer, Robarts Clinical Trials, Roche, Sanofi, Shire, Takeda, UCB and Vifor Pharma. This author has also stock ownership of Inception IBD, San Diego, CA, USA. Melanie Serrero has received lecture or consulting fees from Abbvie, Ferring, Amgen, Celltrion, Janssen, Ferring, Takeda and Tillotts. Jerome Filippi has received lecture and consulting fees from Abbvie, Amgen, Biogen, Ferring, HAC Pharma, Janssen, MSD, Pfizer, Sandoz and Takeda. Xavier Roblin reported a relationship with MSD, Abbvie, Amgen, Sandoz, Pfizer, Takeda and Janssen. Guillaume Bouguen received lecture fees from Abbvie, Ferring, MSD, Takeda and Pfizer and consultant fees from Takeda, Janssen. Denis Franchimont is research director of FNRS; he has received educational grants from Abbvie, Takeda, MSD, and has received honoraria fees for lectures or consultancy from Ferring, Falk, Chiesi, Abbvie, MSD, Centocor, Pfizer, Amgen, Janssen, Mundipharma, Takeda and Hospira. Guillaume Savoye has received lecture fees from Vifor Pharma, Takeda, Pfizer, HAC Pharma, Abbvie, MSD, and Ferring France. This author has also received travel accommodations from Ferring, Abbvie, and MSD France as well as a research grant from Ferring. Anthony Buisson has received research funding from Pfizer, lecture fees from Abbvie, Ferring, Hospira, MSD, Janssen, Sanofi-Aventis, Takeda and Vifor Pharma and consulting fees from Abbvie, Biogen, Janssen, Pfizer and Takeda. Edouard Louis has received fees for: Research Grant: Takeda, Pfizer; Educational Grant: Abbvie, Takeda, Janssen; Speaker Fees: Abbvie, Ferring, MSD, Falk, Takeda, Hospira, Janssen, Pfizer, Celgene; Advisory Board: Abbvie, Ferring, MSD, Takeda, Celgene, Hospira, Janssen; Consultant: Abbvie Stephane Nancey has received consulting fees from Merck, Abbvie, Takeda, Ferring, Norgine, Vifor Pharma, Novartis, Janssen Cilag, Hospira, Takeda and HAC Pharma Vered Abitbol has received lecture fees from Amgen, Biogen, Mylan, Sandoz, Pfizer, Takeda, Janssen, Tillots, Gilead, Ferring Jean-Marie Reimund has received consulting fees from Hospira and Pfizer. This author has also received lectures fees from Abbvie, Biocodex, Ferring, Janssen Cilag, Pfizer and Takeda, as well as travel accommodations from Ferring, Abbvie, MSD, Janssen Cilag, Pfizer, Hospira and Takeda Olivier DeWit declares counseling, boards, transport or personal fees from Abbvie, BMS, Celltrion, Ferring, Galapagos, Janssen, Mylan, Pfizer, and Takeda Lucine Vuitton has received lecture fees from Abbvie, MSD, Takeda, Ferring, Janssen and Pfizer, and research grants from MSD, Takeda and Pfizer. Nicolas Mathieu has received consulting fees from Celltrion, Mylan, MSD, Gilead, Sandoz and lecture fees from Abbvie, Amgen, Biogen, Janssen, MSD, Pfizer, Takeda Laurent Peyrin-Biroulet has received consulting fees from Merck, Abbvie, Janssen, Genentech, Ferring, Norgine, Tillots, Vifor, Shire, Therakos, Pharmacosmos, Pilège, BMS, UCB-Pharma, Hospira, Celltrion, Takeda, Biogaran, Boerhinger-Ingelheim, Lilly, Pfizer, and HAC-Pharma. This author has also received lecture fees from Merck, Abbvie, Takeda, Janssen Cilag, Ferring, Norgine, Tillots, Vifor, Therakos, HAC-Pharma, and Mitsubishi. Cyrielle Gilletta received lecture fees from Abbvie, Takeda, Pfizer and Janssen and consulting fees from Abbvie, Janssen and Takeda. Matthieu Allez has received honoraria from Novo Nordisk, MSD, Abbvie, Ferring, Genentech, Janssen, Pfizer, GSK, Hospira, UCB, Novartis, Takeda, Mayolo-Spindler. Stephanie Viennot has received consulting fees from Abbvie, MSD, Takeda, Vifor Pharma and Ferring. Catherine Le Berre has served as a consultant for Abbvie, Janssen and Gilead; reports receiving payment for lectures from AbbVie, Celltrion, Ferring, Fresenius Kabi, Galapagos, Janssen, MSD, Pfizer and Takeda. Medina Boualit has received travel accommodation from Abbvie, Janssen Takeda and Pfizer. Lucile Boivineau has received consulting fees from Abbvie and Tillotts. Mathurin Fumery has received lecture and consulting fees from Abbvie, MSD, Boehringer, Pfizer, Takeda, Janssen and Ferring. Ludovic Caillo received board and lecture fees from Abbvie, Janssen, Pfizer, Takeda, Amgen David Laharie has received counseling, boards, transports and/or fees from Abbvie, Biogaran, Biogen, Ferring, HAC-pharma, Janssen, MSD, Novartis, Pfizer, Prometheus, Roche, Takeda, Theradiag, Tillots. Maria Nachury has received lecture and consulting fees from Abbvie, Adacyte, Amgen, Arena, Biogen, CTMA, Ferring, Gilead, Janssen, Mayoli Spindler, MSD, Pfizer, Takeda, Viatris Aurelien Amiot has received consulting fees from Abbvie, Hospira, Takeda, Gilead and Biocodex as well as lecture fees and travel accommodations from Abbvie, Janssen, Biocodex, Hospira, Ferring, Takeda and MSD. This author has also received advisory board fees from Gilead, Takeda and Abbvie. No conflicts of interest are claimed by the remaining authors., (Copyright © 2023 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Background & Aims: Fatigue is highly prevalent among patients with inflammatory bowel disease (IBD), and only limited treatment options are available. Based on the hypothetical link between low serum tryptophan concentrations and fatigue, we determined the effect of 5-hydroxytryptophan supplementation on fatigue in patients with inactive IBD., Methods: A multicenter randomized controlled trial was performed at 13 Belgian hospitals, including 166 patients with IBD in remission but experiencing fatigue, defined by a fatigue visual analog scale (fVAS) score of ≥5. Patients were treated in a crossover manner with 100 mg oral 5-hydroxytryptophan or placebo twice daily for 2 consecutive periods of 8 weeks. The primary end point was the proportion of patients reaching a ≥20% reduction in fVAS after 8 weeks of intervention. Secondary outcomes included changes in serum tryptophan metabolites, Functional Assessment of Chronic Illness Therapy Fatigue scale, and scores for depression, anxiety, and stress. The effect of the intervention on the outcomes was evaluated by linear mixed modeling., Results: During 5-hydroxytryptophan treatment, a significant increase in serum 5-hydroxytryptophan (estimated mean difference, 52.66 ng/mL; 95% confidence interval [CI], 39.34-65.98 ng/mL; P < .001) and serotonin (3.0 ng/mL; 95 CI, 1.97-4.03 ng/mL; P < .001) levels was observed compared with placebo. The proportion of patients reaching ≥20% reduction in fVAS was similar in placebo- (37.6%) and 5-hydroxytryptophan (35.6%)-treated patients (P = .830). The fVAS reduction (-0.18; 95% CI, -0.81 to 0.46; P = .581) and Functional Assessment of Chronic Illness Therapy Fatigue scale increase (0.68; 95% CI, -2.37 to 3.73; P = .660) were both comparable between 5-hydroxytryptophan and placebo treatment as well as changes in depression, anxiety, and stress scores., Conclusions: Despite a significant increase in serum 5-hydroxytryptophan and serotonin levels, oral 5-hydroxytryptophan did not modulate IBD-related fatigue better than placebo. (Trial Registration: Belgian Federal Agency for Medication and Health Products, EudraCT number: 2017-005059-10 and ClinicalTrials.gov: NCT03574948, https://clinicaltrials.gov/ct2/show/NCT03574948.)., (Copyright © 2022 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background and Aims: Optimal management of patients with inflammatory bowel disease [IBD] after anti-tumour necrosis factor [TNF] discontinuation due to severe induced skin lesions is unclear. Our study aimed to describe dermatological and IBD evolution after anti-TNF discontinuation for this side effect., Methods: We conducted a multicentre retrospective study including consecutive IBD patients who discontinued anti-TNF due to severe induced skin lesions. Our objectives were to determine factors associated with dermatological remission [complete disappearance of skin lesions] and with IBD relapse in patients with inactive disease at inclusion, notably the impact of an early switch to another biological agent within 3 months of anti-TNF discontinuation., Results: Among the 181 patients [134 women, 160 Crohn's disease] included in the 13 participating centres, dermatological remission occurred in 110 [62%] patients with a median [interquartile range, IQR] interval of 8.0 [6.8-11.0] months. Scalp location was independently associated with less remission of skin lesions (hazard ratio [HR] = 0.64 [95% CI 0.43-0.94], p = 0.02) while early switch was independently associated with a higher probability of remission of skin lesions (HR = 1.64 [95% CI 1.1-2.5], p = 0.02). Among the 148 patients with inactive IBD at inclusion, disease relapse occurred in 75 [51%] patients with a median [IQR] interval of 26.0 [23.0-39.1] months. Survival rates without IBD relapse at 1 year were 85.8% [95% CI 77.5-94.9] in the early switch group and 59.3% [95% CI 48.9-71.9] in the other group [p < 0.01]., Conclusions: Early switch to a new biological is associated with a higher probability of healing of anti-TNF-induced skin lesions and significantly reduces the risk of IBD relapse., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background and Aim: The inflammatory bowel disease [IBD]-disk is a 10-item self-questionnaire that is used to assess IBD-related disability. The aim of the present study was to evaluate this tool in the assessment of IBD daily-life burden., Methods: A 1-week cross-sectional study was conducted in 42 centres affiliated in France and Belgium. Patients were asked to complete the IBD-disk [best score: 0, worst score: 100] and a visual analogue scale [VAS] of IBD daily-life burden [best score: 0, worst score: 10]. Analyses included internal consistency, correlation analysis, and diagnostic performance assessment., Results: Among the 2011 IBD outpatients who responded to the survey [67.8% of the patients had Crohn's disease], 49.9% were in clinical remission. The IBD-disk completion rate was 73.8%. The final analysis was conducted in this population [n = 1455 patients]. The mean IBD-disk score and IBD daily-life burden VAS were 39.0 ± 23.2 and 5.2 ± 2.9, respectively. The IBD-disk score was well correlated with the IBD daily-life burden VAS [r = 0.67; p <0.001]. At an optimal IBD-disk cut-off of 40, the area under the receiver operating characteristic curve [AUROC] for high IBD daily-life burden [VAS >5] was 0.81 (95% confidence interval [CI]: 0.79-0.83; p <0.001)., Conclusions: In a large cohort of patients, the IBD-disk score was well correlated with IBD daily-life burden, and it could be used in clinical practice., (© The Author(s) 2020. Published by Oxford University Press on behalf of European Crohn’s and Colitis Organisation. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Patients' experience with healthcare professionals could influence their clinical outcomes., Aims: To assess inflammatory bowel disease (IBD) patients' experience with their disease, their treatment and their relationship with their physician., Methods: A one-week cross-sectional study was conducted in 42 IBD centres. 2011 consecutive outpatients with IBD completed an anonymous self-report questionnaire assessing their experience with and knowledge of IBD., Results: A quantitative assessment of the doctor-patient relationship revealed that patients' knowledge of IBD and IBD treatment ranged from 7.4 to 8.3 out of 10. In addition to IBD physicians, other sources of information about IBD and current treatment mainly included the internet (80% and 63%, respectively) and general practitioners (61% and 54%). Knowledge about education programmes (28%) was poor, resulting in a lack of willingness to further use these resources (25%). Concerns about IBD treatment were raised in 76% of patients, mostly related to the fear of adverse events (47%) and a lack of efficacy (33%). The need of alternative healthcare professionals was reported by 89% of the sample., Conclusion: In a large cohort of patients, we highlighted gaps in the management of patients with IBD regarding the need for higher-quality information and the implementation of alternative healthcare professionals., (Copyright © 2020 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Background and Study Aims: Vedolizumab (VDZ) is a gutselective integrin inhibitor used to treat Crohn's disease (CD) and ulcerative colitis (UC). This retrospective study assessed effectiveness and treatment persistence of VDZ in a Belgian reallife cohort of CD and UC patients., Patients and Methods: CD and UC patients from 15 Belgian centers, who started VDZ between 01/09/2015 and 31/06/2016 and attended ≥1 visit after the first VDZ infusion, were included. Data were collected before first infusion, at week (W)10, W14 (CD patients only), month (M)6 and last follow-up. Treatment response and remission rates (changes in disease activity scores) and treatment persistence (Kaplan-Meier analysis) were assessed., Results: Of the 348 patients receiving at least one dose of VDZ, 325 (202 CD, 45 biologic-naïve; and 123 UC, 42 biologic-naïve) patients were included in data analyses. At M6, 87.6% (176/201) of CD and 86.1% (105/122) of UC patients were still on VDZ treatment, 75.6% (34/45) and 83.9% (26/31) achieved clinical response, and 66.7% (44/66) and 42.9% (15/35) were in remission. At M6 remission rates was significantly higher while response rates tended to be higher among biologic-naïve versus biologic-failure CD patients., Conclusions: VDZ offers an effective treatment option in real-life settings and treatment effectiveness appears higher in biologic-naïve versus biologic-failure CD patients. (Acta gastroenterol. belg., 2020, 83, 15-23)., (© Acta Gastro-Enterologica Belgica.)

Background: Whether healthcare workers with inflammatory bowel disease (IBD) are at increased risk of severe infection due to daily pathogen exposure is controversial., Aim: To assess the risk of severe infection in healthcare workers with IBD in a large multicentre case-control study., Methods: The study population comprised 482 healthcare workers with IBD from 17 centres who were matched for gender, age, disease subtype and year of diagnosis to 482 controls (non-healthcare workers with IBD). The study period was between the date of diagnosis of IBD and June 2016. Severe infection was defined as any community-acquired infection that required hospitalisation., Results: With a median follow-up of 9.3 years, 139 severe infections were recorded among cases and controls, including 30 Clostridium difficile infections, 33 severe viral infections, nine tuberculosis infections, 21 community-acquired pneumonia and 46 others. No difference was observed between healthcare workers and controls regarding the overall incidence rates of severe infection. An increased risk of tuberculosis was noted in healthcare workers. In multivariate analysis in the entire study population, severe infection was associated with current exposure to corticosteroids (OR = 3.05, 95% CI [2.06-4.52], P < 0.001), immunosuppressants (OR = 1.98, 95% CI [1.38-2.84], P < 0.001) and anti-TNF agents (OR = 2.93, 95% CI [2.02-4.27], P < 0.001) and reduced with Crohn's disease (OR = 0.63, 95% CI [0.43-0.91], P = 0.01)., Conclusions: Healthcare workers with IBD do not have an increased risk of severe infection compared with other patients with IBD, except for tuberculosis. Screening for tuberculosis exposure should be assessed in this high-risk population when treated with anti-TNF agents., (© 2018 John Wiley & Sons Ltd.)

Background and Aims: Acute optic neuritis [ON] is an inflammatory condition affecting the optic nerve. Clinicians should suspect optic neuritis in cases of painful and rapidly progressive loss of central visual field. This condition may be associated with a multitude of diseases, and mostly with multiple sclerosis [MS] where it may present as an initial symptom. The literature reports that optic neuritis and MS occur in patients with inflammatory bowel disease [IBD] before and after the era of anti-tumour necrosis factor-α [TNFα] drugs. At the present moment, there is little consensus for managing this complication, currently treated with corticosteroids and discontinuation of the causative agents., Methods: We collected cases through a retrospective multicentre European Crohn's and Colitis Organisation CONFER [COllaborative Network For Exceptionally Rare case reports] project. We also performed a comprehensive retrospective search of the available literature on this topic., Results: We report herein 12 new cases of ON, including 10 under anti-TNF therapy, collected through the CONFER project. We also compare characteristics of ON associated or not with anti-TNFα agents., Conclusions: The exceptional and current observation of distant family history of MS in 17% of our patients who developed ON, despite the small number and the lack of a control arm, might be an important signal that should be taken into account in our therapeutic strategies in the future., (Copyright © 2016 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background and Aims: TPMT deficiency is associated with azathioprine (AZA)-induced myelosuppression (MS). However, in one previous study, only about ¼ of MS episodes in Crohn's Disease patients under AZA can be attributed to TPMT deficiency. Recently, new TPMT mutations have been described and our aim is to investigate their clinical relevance before and after a first MS episode on thiopurine therapy., Methods: Clinical data from 61 IBD patients having developed MS during AZA therapy were collected. Sequencing analysis was carried out on TPMT cDNA for the presence of all currently known mutations., Results: Only TPMT *2, *3A and *3C mutations were found in this cohort. TPMT mutations were observed in 15 out of 61 patients (25%). Four out of 15 were homozygous for a TPMT mutation (low methylator, LM genotype) and 11 were heterozygous (intermediate methylator, IM genotype). Median delays of MS onset were 2, 2.75 and 6months in the LM, IM and HM (high methylator, wild type TPMT) groups, respectively. After the first MS episode, 36 patients resumed thiopurine treatment of which 13 experienced a second MS episode. This second episode was also rarely associated with TPMT mutations., Conclusions: One quarter of MS episodes during AZA were associated with TPMT deficient genotype. After a first leucopenia episode, thiopurine therapy may be resumed in a majority of patients independently of their TPMT genotype., (Copyright © 2011 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Genome-wide association studies (GWAS) have identified dozens of risk loci for many complex disorders, including Crohn's disease. However, common disease-associated SNPs explain at most ∼20% of the genetic variance for Crohn's disease. Several factors may account for this unexplained heritability, including rare risk variants not adequately tagged thus far in GWAS. That rare susceptibility variants indeed contribute to variation in multifactorial phenotypes has been demonstrated for colorectal cancer, plasma high-density lipoprotein cholesterol levels, blood pressure, type 1 diabetes, hypertriglyceridemia and, in the case of Crohn's disease, for NOD2 (refs. 14,15). Here we describe the use of high-throughput resequencing of DNA pools to search for rare coding variants influencing susceptibility to Crohn's disease in 63 GWAS-identified positional candidate genes. We identify low frequency coding variants conferring protection against inflammatory bowel disease in IL23R, but we conclude that rare coding variants in positional candidates do not make a large contribution to inherited predisposition to Crohn's disease.

Background: Thiopurines (TP) are widely used in the management of inflammatory bowel diseases. Side effects and inefficacy are a major concern as they lead to withdrawal of the drug., Materials and Methods: Tools investigating TP metabolism are useful to avoid inadequate cessation of TP therapy., Results: TP metabolism is complex and many enzymes are involved. Among them, Thiopurine methyl transferase is the only one routinely measured by pheno- or genotyping. A decreased TPMT activity results in a potential overdosing of TP drugs leading to myelotoxicity, whereas an ultra-high activity leads to TP ineffectiveness and overproduction of methylated compounds responsible for hepatotoxicity. TPMT determination prior to TP treatment results in an individual adapted dose. Xanthine oxidase/dehydrogenase (XOD), inosine triphosphate pyrophosphatase (ITPA) and glutathion-S-transferase (GST) are other promising enzyme targets that might help to explain TP efficacy or toxicity. ITPA and GST polymorphisms might potentially be related to some TP side effects, while a XOD inhibition by allopurinol could avoid TP-related hepatotoxicity., Conclusions: Utilization of thiopurine metabolites, 6-thioguanine nucleotides and 6-methylmercaptopurine, is discussed, specifically, in case of thiopurine failure and recommendations are given about their interpretation and potential dose optimization. These enzymes and metabolites tests are complementary to the regular monitoring of blood cells count and liver tests which remains mandatory., (© 2010 The Authors. European Journal of Clinical Investigation © 2010 Stichting European Society for Clinical Investigation Journal Foundation.)

Thiopurines (TP) are widely used in the management of inflammatory bowel diseases. Side-effects and inefficacy are a major concern as they lead to withdrawal of the drug. Tools investigating TP metabolism are useful to avoid inadequate cessation of TP therapy. TP metabolism is complex and many enzymes are involved. Among them, Thiopurine methyltransferase (TPMT) is the only one routinely measured by pheno- or genotyping. In this review, the rationale for TPMT and thiopurine metabolites, 6-thioguanine nucleotides and 6-methylmercaptopurine, determination in clinical practice is discussed, specifically in case of thiopurine failure and recommendations are given about their interpretation and potential dose optimization of TP drugs.

Inflammatory bowel diseases comprise Crohn's disease, ulcerative colitis and indeterminate colitis, generally beginning in young subjects and increasing in frequency in Western countries. Despite their still unknown aetiologies, some pathogenic mechanisms have been elucidated after the recent discovery of numerous susceptibility genes and rare environmental factors. These diseases have a course consisting of episodes of flare-up alternating with periods of remission. Medical treatment for induction of a remission comprises besides aminosalicylates, corticosteroids including budesonide and immunosuppressive drugs, anti-TNF-alpha drugs (infliximab, adalimumab) indicated in case of failure of previous therapies. Surgery is indicated for complications and failure of medical treatment.With current therapy, most of the patients are able to fulfil their familial, social and professional projects.

The inflammatory bowel diseases (IBD) Crohn's disease and ulcerative colitis are common causes of morbidity in children and young adults in the western world. Here we report the results of a genome-wide association study in early-onset IBD involving 3,426 affected individuals and 11,963 genetically matched controls recruited through international collaborations in Europe and North America, thereby extending the results from a previous study of 1,011 individuals with early-onset IBD. We have identified five new regions associated with early-onset IBD susceptibility, including 16p11 near the cytokine gene IL27 (rs8049439, P = 2.41 x 10(-9)), 22q12 (rs2412973, P = 1.55 x 10(-9)), 10q22 (rs1250550, P = 5.63 x 10(-9)), 2q37 (rs4676410, P = 3.64 x 10(-8)) and 19q13.11 (rs10500264, P = 4.26 x 10(-10)). Our scan also detected associations at 23 of 32 loci previously implicated in adult-onset Crohn's disease and at 8 of 17 loci implicated in adult-onset ulcerative colitis, highlighting the close pathogenetic relationship between early- and adult-onset IBD.

This chapter is an overview of the literature on serological markers of inflammatory bowel diseases (IBD), focusing on anti-neutrophil cytoplasm autoantibodies (ANCA) and anti- Saccharomyces cerevisiae mannan antibodies (ASCA). The methodology for ANCA and ASCA testing is first introduced. The value of these markers as diagnostic tools is then discussed. Other chapters are devoted to the potential role of ANCA and ASCA in disease monitoring, disease stratification and as subclinical markers in families. Finally reviewed are other antibodies recently tested in clinical trials such as pancreatic antibodies and antibodies directed against bacterial antigens. The role of these antibodies in the pathophysiology of IBD still needs to be assessed. We also need to identify the ASCA immunogen(s) eliciting the antibody response.