Differences in Clinical Course, Genetics, and the Microbiome Between Familial and Sporadic Inflammatory Bowel Diseases

Association of inflammatory bowel disease in first-degree relatives with risk of colorectal cancer: A nationwide case-control study in Sweden

This study aims to assess the association between inflammatory bowel disease (IBD) history in first-degree relatives (FDRs) and colorectal cancer (CRC) risk. We conducted a nationwide case-control study in Sweden among 69 659 CRC cases and 343 032 non-CRC controls matched on age, sex, birth year and residence county. Through linkage of multi-generation register and the nationwide ESPRESSO (Epidemiology Strengthened by histoPathology Reports in Sweden) cohort, we ascertained IBD diagnoses among parents, full siblings and offspring of the index individuals. Odds ratios (ORs) of CRC associated with IBD family history were calculated using conditional logistic regression. 2.2% of both CRC cases (1566/69659) and controls (7676/343027) had ≥1 FDR with IBD history. After adjusting for family history of CRC, we observed no increased risk of CRC in FDRs of IBD patients (OR, 0.96; 95%CI, 0.91-1.02). The null association was consistent according to IBD subtype (Crohn's disease or ulcerative colitis), number of FDRs with IBD (1 or ≥ 2), age at first IBD diagnosis in FDRs (<18, 18-39, 40-59 or ≥60 years), maximum location/extent of IBD or FDR relation (parent, sibling or offspring). The null association remained for early-onset CRC (diagnosed at age <50 years). In conclusion, IBD history in FDRs was not associated with an increased risk of CRC. Our findings suggest that extra screening for CRC may not be needed in the offspring, siblings or parents of IBD patients, and strengthen the theory that it is the actual inflammation or atypia of the colon in IBD patients that confers the increased CRC risk.

The genetics of non-monogenic IBD

Inflammatory bowel disease (IBD), with Crohn's disease and ulcerative colitis as main subtypes, is a prototypical multifactorial disease with both genetic and environmental factors involved. Genetically, IBD covers a wide spectrum from monogenic to polygenic forms. In polygenic disease, many genetic variants each contribute a small amount to disease risk. With the advent of genome-wide association studies (GWAS), it became possible to find these variants and corresponding genes, leading so far to the discovery of ca 240 loci associated with IBD. Together, these however explain only 20-25% of the heritability of IBD, leaving a large portion unaccounted for. This missing heritability might be hidden in common variants with even lower effect than the ones currently found through GWAS, but also in rare variants which can be found through large-scale sequencing studies or potentially in multiplex families. In this review, we will give an overview of the current knowledge about the genetics of non-monogenic IBD and how it differs from the monogenic form(s), and future perspectives. The history of IBD genetic studies from twin studies over linkage studies to GWAS, and finally large-scale sequencing studies and the revisiting of multiplex families will be discussed.

Inflammatory bowel disease in families with four or more affected first-degree relatives

BACKGROUND

Family history increases the risk for inflammatory bowel diseases (IBDs). However, data on differences in phenotypic characteristics among patients with a strong family history of IBD are scarce and controversial. The aim of the study was to compare the phenotypic features of IBD patients with four or more affected first-degree relatives with sporadic cases of IBD.

METHODS

Patients with familial and sporadic IBD were identified from the institutional IBD database. IBD patients from families with at least four first-degree affected relatives were selected for analysis and were compared to non-matched sporadic cases with IBD chosen randomly. Comparison for type of IBD (Crohn's disease (CD) vs. ulcerative colitis (UC)), age at onset as well as for disease extent, behavior, extraintestinal manifestations and indicators of severe disease were analyzed.

RESULTS

Thirty-five patients with familial IBD (28 CD, seven UC) were compared to 88 sporadic IBD patients (61 CD, 24 UC and three IBDU). Disease duration was 10.3 ± 8.2 in the familial and 8.0 ± 7.2 years in the sporadic cases, p=.13. The familial cases were younger at diagnosis (19.3 ± 8.6 vs. 25.7 ± 11.8, p=.004). Patients with familial compared to sporadic IBD were significantly more likely to require steroid treatment (80% vs. 54.5%, p=.009), biological treatment (94.3%, vs. 63.6%, p<.001) or surgery (25.7%, vs. 11.4%, p=.048).

CONCLUSIONS

IBD with a very strong positive family history is associated with younger age at onset and a more adverse IBD phenotype compared to sporadic IBD.

The risk of subsequent surgery following bowel resection for Crohn's disease in a national cohort of 19 207 patients

AIM

Surgery is required for most patients with Crohn's disease (CD) and further surgery may be necessary if medical treatment fails to control disease activity. The aim of this study was to characterize the risk of, and factors associated with, further surgery following a first resection for Crohn's disease.

METHODS

Hospital Episode Statistics from England were examined to identify patients with CD and a first recorded bowel resection between 2007 and 2016. Multivariable logistic regression was used to examine risk factors for further resectional surgery within 5 years. Prevalence-adjusted surgical rates for index CD surgery over the study period were calculated.

RESULTS

In total, 19 207 patients (median age 39 years, interquartile range 27-53 years; 55% women) with CD underwent a first recorded resection during the study period. 3141 (16%) underwent a further operation during the study period. The median time to further surgery was 2.4 (interquartile range 1.2-4.6) years. 3% of CD patients had further surgery within 1 year, 14% by 5 years and 23% by 10 years. Older age (≥58), index laparoscopic surgery and index elective surgery (adjusted OR 0.65, 95% CI 0.54-0.77; 0.77, 0.67-0.88; and 0.77, 0.69-0.85; respectively) were associated with a reduced risk of further surgery by 5 years. Prior surgery for perianal disease (1.60, 1.37-1.87), an extraintestinal manifestation of CD (1.51, 1.22-1.86) and index surgery in a high-volume centre for CD surgery (1.20, 1.02-1.40) were associated with an increased risk of further surgery by 5 years. A 25% relative and 0.3% absolute reduction in prevalence-adjusted index surgery rates for CD was observed over the study period.

CONCLUSIONS

Further surgery following an index operation is common in CD. This risk was particularly seen in patients with perianal disease, extraintestinal manifestations and those who underwent index surgery in a high-volume centre.

Genetic and Epigenetic Etiology of Inflammatory Bowel Disease: An Update

Inflammatory bowel disease (IBD) is a chronic disease with periods of exacerbation and remission of the disease. The etiology of IBD is not fully understood. Many studies point to the presence of genetic, immunological, environmental, and microbiological factors and the interactions between them in the occurrence of IBD. The review looks at genetic factors in the context of both IBD predisposition and pharmacogenetics.

Differences in the Intestinal Flora of Patients with Inflammatory Bowel Disease in Southwest China

To study changes in the intestinal flora associated with inflammatory bowel disease (IBD) in the Han population of southwest China, 48 participants were enrolled, 18 of whom had been diagnosed with IBD. Stool samples were collected from the participants. Sequencing of 16S rRNA gene was used to measure and identify the components of the intestinal flora. Diversity analysis and multivariate statistical analysis were conducted to study differences in intestinal flora between patients with IBD and healthy controls. The goods coverage, observed species, Shannon, and Simpson indices of alpha diversity were different (p < 0.05). Beta diversity analysis yielded significant differences between groups (R = 0.5668, p = 0.001 < 0.05). Compared with the composition of the intestinal flora in healthy controls, the relative abundances of Proteobacteria (18.56% vs. 3.56%, p = 0.001) and Fusobacterium (2.08% vs. 0.35%, p = 0.005) were higher in patients with IBD. Therefore, this study provides insight into the role of the microbiome in IBD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-022-01014-z.

Clinical Phenotype and Disease Course of Inflammatory Bowel Disease: A Comparison Between Sporadic and Familial Cases

BACKGROUND

The role of genetic and environmental factors in inflammatory bowel disease's (IBD) clinical course is not fully clear. We aimed to assess the clinical phenotype, disease course, and prognosis of familial IBD in comparison with sporadic cases.

METHODS

We conducted a prospective national matched case-control study of registered IBD patients in the Iranian Registry of Crohn's and Colitis (IRCC) recruited from 2017 until 2020. Sporadic and familial IBD patients were matched based on age, sex, and disease duration. Data on demographics, past medical disease, family history of IBD, disease type, clinical phenotype, extraintestinal manifestations, IBD medications, IBD activity using the IBD-control-8 questionnaire and the Manitoba IBD index, emergency visits in the past 12 months, admissions in the past 3 months, history of colon cancer, IBD-related surgeries, and aggressive phenotype were gathered. Variable distributions were compared between sporadic and familial cases.

RESULTS

Overall, 5231 patients with ulcerative colitis (UC, 18.3% familial) and 1438 patients with Crohn's disease (CD, 16.7% familial) were registered in the IRCC. Age at diagnosis was similar between familial and sporadic cases. After matching, 3523 UC patients and 908 CD patients were enrolled in the study. Extraintestinal manifestations, UC extent, CD location and behavior, anti-TNF use, disease activity, colon cancer, IBD-related surgeries and the aggressive phenotype were similar between these sporadic and familial cases.

CONCLUSIONS

The prevalence of familial UC and CD cases in Iran was more similar to western countries, and family history did not show a predictive value for disease phenotype, course, and outcomes in our study.

Multi-Omics Analysis of Western-style Diet Increased Susceptibility to Experimental Colitis in Mice

Background

Western-style diet (WSD) is associated with inflammatory bowel disease (IBD) prevalence. However, the impact of WSD on IBD development and its underlying mechanism remain unclear. Transcriptomics and metabolomics could be beneficial for identifying key factors in WSD-related experimental IBD susceptibility. However, no such study has been conducted yet. We aimed to analyze the implications of WSD for experimental colitis susceptibility in mice and its underlying mechanism using these high-throughput technologies.

Methods

We fed experimental mice a WSD and a control diet from weaning. After 9 weeks, the mice were treated with 2,4,6 trinitrobenzene sulfonic acid to induce colitis, and the control group was treated with 50% ethanol (commonly used IBD animal model). Genome-wide microarray and liquid chromatography-tandem mass spectrometry were used to identify the differential transcripts and metabolites of experimental colitis with and without pre-illness WSD.

Results

WSD induced more severe inflammation in experimental colitis than the control diet. We found 2540 up-regulated genes and 2737 down-regulated genes in experimental colitis with WSD compared with those for the control diet. In addition, levels of 41 colonic tissue metabolites and 56 serum metabolites showed significant differences. Integrating transcriptomic and metabolomic data, we found major co-expression networks through which WSD promoted experimental IBD susceptibility, including enzymes of biotransformation, glycan synthesis and metabolism, steroid hormone metabolites.

Conclusion

Pre-illness WSD increased experimental colitis susceptibility. Our results could provide important evidences for the potential mechanisms and assist dietary recommendations to better manage IBD.

Increasing rate of a positive family history of inflammatory bowel disease (IBD) in pediatric IBD patients

The role of a positive family history in pediatric inflammatory bowel disease (IBD) in the era of biologic therapy has not been elucidated. We retrospectively reviewed the medical records of children with IBD and retrieved demographic and clinical characteristics, including the presence of a positive family history of IBD, IBD phenotype, disease course, and therapy. Overall, 325 children (age range at diagnosis 11-15 years) were included, of whom 82 (25.2%) had a positive family history. Children diagnosed during 2016-2020 had a higher frequency of positive family history compared to those diagnosed during 2010-2015 (31.8% versus 20.7%, respectively, p = 0.024). Children with a positive family history had a higher risk for a stricturing phenotype than those with a negative family history (11.3% versus 2.8%, respectively, p = 0.052). They more often received nutritional therapy (53.7% versus 36.6%, p = 0.007) and less often received corticosteroids (36.6% versus 52.7%, p = 0.012). More children with a negative family history needed intensification of biologic therapy (p = 0.041).Conclusion: The rate of a positive family history of IBD in the pediatric IBD population is increasing. A positive family history may have some impact upon IBD phenotype but none on IBD outcome. What is Known: •Familial clustering of inflammatory bowel disease (IBD) has been reported in 5%-15% of IBD patients. •The investigation of the impact of a positive family history upon IBD characteristics and severity revealed conflicting results. What is New: •In this cohort of 325 children with IBD, 25.2% had a positive family history. •The rate of a positive family history of IBD in the pediatric IBD population is increasing. •A positive family history may have some impact upon IBD phenotype but none on IBD outcome.

Results of the Seventh Scientific Workshop of ECCO: Precision Medicine in IBD-Prediction and Prevention of Inflammatory Bowel Disease

Inflammatory bowel disease [IBD] is a complex chronic disorder with no clear aetiology and no known cure. Despite recent advances in overall disease management and improved therapeutics, patients with IBD still experience a substantial burden. Furthermore, as the incidence continues to increase in developing areas of the world, it is expected that the burden of IBD to society will increase and exert tremendous pressure on health care systems worldwide. Therefore, new strategies to prevent the global increase of IBD are urgently required. Data are being progressively acquired on the period preceding disease diagnosis, which support the concept that IBD has a preclinical period that may reveal the triggers of disease and may be amenable to early intervention. Having a better knowledge of this preclinical period will increase the potential not only for improved understanding of disease pathogenesis and improved therapeutics, but also for disease prediction and prevention.

Host Genetic and Gut Microbial Signatures in Familial Inflammatory Bowel Disease

INTRODUCTION:

The family history of inflammatory bowel disease (IBD) has been strongly associated with risk of developing IBD. This study aimed to identify the host genetic and gut microbial signatures in familial IBD.

METHODS:

Genetic analyses using genome-wide single nucleotide polymorphism genotyping and whole exome sequencing were performed to calculate weighted genetic risk scores from known IBD-associated common variants and to identify rare deleterious protein-altering variants specific to patients with familial IBD in 8 Korean families that each included more than 2 affected first-degree relatives (FDRs) and their unaffected FDR(s). In parallel, gut microbial community was analyzed by 16S rRNA sequencing of stools from the sample individuals.

RESULTS:

The risk of familial IBD was not well explained by the genetic burden from common IBD-risk variants, suggesting the presence of family-shared genetic and environmental disease-risk factors. We identified 17 genes (AC113554.1, ACE, AKAP17A, AKAP9, ANK2, ASB16, ASIC3, DNPH1, DUS3L, FAM200A, FZD10, LAMA5, NUTM2F, PKN1, PRR26, WDR66, and ZC3H4) that each contained rare, potentially deleterious variants transmitted to the affected FDRs in multiple families. In addition, metagenomic analyses revealed significantly different diversity of gut microbiota and identified a number of differentially abundant taxa in affected FDRs, highlighting 22 novel familial disease-associated taxa with large abundance changes and the previously reported gut dysbiosis including low alpha diversity in IBD and 16 known IBD-specific taxa.

DISCUSSION:

This study identified familial IBD-associated rare deleterious variants and gut microbial dysbiosis in familial IBD.

The Gut Microbial Profile of Preclinical Crohn's Disease Is Similar to That of Healthy Controls

BACKGROUND AND AIMS

It is unclear whether microbial dysbiosis plays an etiologic role in Crohn's disease (CD) or is the result of protracted inflammation. Here, we test the hypothesis that dysbiosis predates clinical CD in asymptomatic first-degree relatives (FDRs) of CD patients: normal (FDR1), with borderline inflammation (FDR2), and with frank, very early inflammation (FDR3).

METHODS

The gut microbial diversity was tested in ileocecal biopsies through next generation sequencing of the 16S rRNA gene in 10 healthy controls (HCs), 22 patients with active, untreated CD, and 25 FDRs (9 FDR1; 12 FDR2; 4 FDR3). The metagenomic functions of 41 microbiome-related processes were inferred by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis.

RESULTS

Compared with HCs, alpha diversity in CD patients was decreased, with an observed decrease in Faecalibacterium prausnitzii and increase in Bacteroides fragilis. In FDRs, microbial diversity was unchanged compared with HCs. In Operational Taxonomic Units and PICRUSt Principal coordinates and component analyses, the ellipse centroid of FDRs was diagonally opposed to that of CD patients, but close to the HC centroid. In both analyses, statistically significant differences in terms of beta diversity were found between CD and HC but not between FDR and HC.

CONCLUSIONS

In FDRs (including FDR3-who bear preclinical/biologic onset disease), we found that the microbial profile is remarkably similar to HC. If confirmed in larger studies, this finding suggests that clinical CD-associated dysbiosis could result from the changed microenvironment due to disease evolution over time.

Diagnosis and natural history of preclinical and early inflammatory bowel disease

Inflammatory bowel disease is a chronic and progressive disorder of the gastrointestinal tract. A relevant proportion of patients develop complicated lesions, defined as strictures, fistulas and/or abscesses already at diagnosis, and this proportion increases over time. The preclinical phase defines the period of time from the appearance of the first immune disturbances until the development of overt disease, and it may be present months to years before the diagnosis. Multiple biomarkers (e.g., C-reactive protein, interleukin-6, fecal calprotectin) and cellular mechanisms (e.g., complement cascade, lysosomes, innate immunity, and glycosaminoglycan metabolism) are already altered during this period. Research in this area allows the description of the initial immune disturbances that may identify potential targets and lead to the development of new drug therapies. During this period, different interventions in high-risk individuals, including drugs or environmental factors, will open the possibility of innovative strategies focused on the reduction of complications, or even prevention trials for inflammatory bowel disease. Here, we review the most relevant findings regarding the characteristics, prevalence and biomarkers associated with preclinical disease, along with their possible use in our future clinical practice.

Concordance regarding disease type and phenotypic characteristics among patients with familial inflammatory bowel disease

BACKGROUND AND AIMS

The phenotypic concordance among familial cases of inflammatory bowel disease (IBD) has been rarely reported. Thus, the present study aimed to evaluate the concordance regarding disease type and phenotypic features in a large cohort of Korean patients with IBD.

METHODS

A total of 6647 patients with IBD who visited the Asan Medical Center between June 1989 and September 2016 were enrolled in the study. When at least two familial cases existed in our cohort, they were included in the concordance analysis (κ index). The concordance between younger and older members for IBD type [Crohn's disease (CD) and ulcerative colitis (UC)] and phenotypic characteristics such as disease extent and location, disease behavior, the use of medication, and need for surgery were evaluated.

RESULTS

A positive family history of IBD was noted in 216 patients with CD (7.0%) and in 238 patients with UC (6.7%). Of all patients, 167 consanguineous pairs in 146 families were identified. The crude concordance rate for IBD type was 82.6% with a κ index of 0.656 [95% confidence interval (CI): 0.545-0.768, good concordance]. There was mild concordance for disease location in CD (κ = 0.256; 95% CI: 0.007-0.505) and for the use of antitumor necrosis factor agents in UC (κ = 0.354; 95% CI: -0.049-0.757). The concordance for IBD type and several phenotypes in first-degree relative pairs was better than that in the entire pairs.

CONCLUSIONS

Disease type and phenotypic characteristics of patients with familial IBD may be anticipated.

Role of Selenoproteins in Bacterial Pathogenesis

The trace element selenium is an essential micronutrient that plays an important role in maintaining homeostasis of several tissues including the immune system of mammals. The vast majority of the biological functions of selenium are mediated via selenoproteins, proteins which incorporate the selenium-containing amino acid selenocysteine. Several bacterial infections of humans and animals are associated with decreased levels of selenium in the blood and an adjunct therapy with selenium often leads to favorable outcomes. Many pathogenic bacteria are also capable of synthesizing selenocysteine suggesting that selenoproteins may have a role in bacterial physiology. Interestingly, the composition of host microbiota is also regulated by dietary selenium levels. Therefore, bacterial pathogens, microbiome, and host immune cells may be competing for a limited supply of selenium. Elucidating how selenium, in particular selenoproteins, may regulate pathogen virulence, microbiome diversity, and host immune response during a bacterial infection is critical for clinical management of infectious diseases.

Molecular Profiling of Inflammatory Bowel Disease: Is It Ready for Use in Clinical Decision-Making?

Inflammatory bowel disease (IBD) is a heterogeneous disorder in terms of age at onset, clinical phenotypes, severity, disease course, and response to therapy. This underlines the need for predictive and precision medicine that can optimize diagnosis and disease management, provide more cost-effective strategies, and minimize the risk of adverse events. Ideally, we can leverage molecular profiling to predict the risk to develop IBD and disease progression. Despite substantial successes of genome-wide association studies in the identification of genetic variants affecting IBD susceptibility, molecular profiling of disease onset and progression as well as of treatment responses has lagged behind. Still, thanks to technological advances and good study designs, predicting phenotypes using genomics and transcriptomics in IBD has been rapidly evolving. In this review, we summarize the current status of prediction of disease risk, clinical course, and response to therapy based on clinical case presentations. We also discuss the potential and limitations of the currently used approaches.

A Distance-Based Kernel Association Test Based on the Generalized Linear Mixed Model for Correlated Microbiome Studies

Researchers have increasingly employed family-based or longitudinal study designs to survey the roles of the human microbiota on diverse host traits of interest (e. g., health/disease status, medical intervention, behavioral/environmental factor). Such study designs are useful to properly control for potential confounders or the sensitive changes in microbial composition and host traits. However, downstream data analysis is challenging because the measurements within clusters (e.g., families, subjects including repeated measures) tend to be correlated so that statistical methods based on the independence assumption cannot be used. For the correlated microbiome studies, a distance-based kernel association test based on the linear mixed model, namely, correlated sequence kernel association test (cSKAT), has recently been introduced. cSKAT models the microbial community using an ecological distance (e.g., Jaccard/Bray-Curtis dissimilarity, unique fraction distance), and then tests its association with a host trait. Similar to prior distance-based kernel association tests (e.g., microbiome regression-based kernel association test), the use of ecological distances gives a high power to cSKAT. However, cSKAT is limited to handling Gaussian traits [e.g., body mass index (BMI)] and a single chosen distance measure at a time. The power of cSKAT differs a lot by which distance measure is used. However, choosing an optimal distance measure is challenging because of the unknown nature of the true association. Here, we introduce a distance-based kernel association test based on the generalized linear mixed model (GLMM), namely, GLMM-MiRKAT, to handle diverse types of traits, such as Gaussian (e.g., BMI), Binomial (e.g., disease status, treatment/placebo) or Poisson (e.g., number of tumors/treatments) traits. We further propose a data-driven adaptive test of GLMM-MiRKAT, namely, aGLMM-MiRKAT, so as to avoid the need to choose the optimal distance measure. Our extensive simulations demonstrate that aGLMM-MiRKAT is robustly powerful while correctly controlling type I error rates. We apply aGLMM-MiRKAT to real familial and longitudinal microbiome data, where we discover significant disparity in microbial community composition by BMI status and the frequency of antibiotic use. In summary, aGLMM-MiRKAT is a useful analytical tool with its broad applicability to diverse types of traits, robust power and valid statistical inference.

Systems biology in inflammatory bowel diseases: on the way to precision medicine

Inflammatory bowel diseases (IBD) are chronic and recurrent inflammatory disorders of the gastrointestinal tract. The elucidation of their etiopathology requires complex and multiple approaches. Systems biology has come to fulfill this need in approaching the pathogenetic mechanisms of IBD and its etiopathology, in a comprehensive way, by combining data from different scientific sources. In combination with bioinformatics and network medicine, it uses principles from computer science, mathematics, physics, chemistry, biology, medicine and computational tools to achieve its purposes. Systems biology utilizes scientific sources that provide data from omics studies (e.g., genomics, transcriptomics, etc.) and clinical observations, whose combined analysis leads to network formation and ultimately to a more integrative image of disease etiopathogenesis. In this review, we analyze the current literature on the methods and the tools utilized by systems biology in order to cover an innovative and exciting field: IBD-omics.

A New Look at Familial Risk of Inflammatory Bowel Disease in the Ashkenazi Jewish Population

BACKGROUND AND AIMS

The inflammatory bowel diseases (IBD) are particularly common among the Ashkenazi Jewish (AJ) population. Population-specific estimates of familial risk are important for counseling; however, relatively small cohorts of AJ IBD patients have been analyzed for familial risk to date. This study aimed to recruit a new cohort of AJ IBD patients, mainly from the UK, to determine the familial occurrence of disease.

METHODS

A total of 864 AJ IBD patients were recruited through advertisements, hospital clinics, and primary care. Participants were interviewed about their Jewish ancestry, disease phenotype, age of diagnosis, and family history of disease. Case notes were reviewed.

RESULTS

The 864 probands comprised 506 sporadic and 358 familial cases, the latter with a total of 625 affected relatives. Of the UK cases, 40% had a positive family history with 25% having at least one affected first-degree relative. These percentages were lower among those recruited through hospital clinics and primary care (33% for all relatives and 22% among first-degree relatives). Examining all probands, the relative risk of IBD for offspring, siblings, and parents was 10.5, 7.4, and 4, respectively. Age of diagnosis was significantly lower in familial versus sporadic patients with Crohn's disease.

CONCLUSIONS

This study reports familial risk estimates for a significant proportion of the AJ IBD population in the UK. The high rate of a positive family history in this cohort may reflect the greater genetic burden for IBD among AJs. These data are of value in predicting the likelihood of future recurrence of IBD in AJ families.