Crohn's disease: concordance for site and clinical type in affected family members--potential hereditary influences

A Systematic Review on the Increasing Incidence of Inflammatory Bowel Disease in Southeast Asia: Looking Beyond the Urbanization Phenomenon

The incidence of inflammatory bowel disease (IBD) has been increasing in Southeast Asia (SEA) in tandem with its economic growth and urbanization over the past 2 decades. Specific characteristics of IBD in SEA are similar to East Asia and the West, such as the declining ratio of ulcerative colitis to Crohn's disease. However, exceptionally low familial aggregation is seen. Smoking is also not a common risk factor in patients with Crohn's disease. The incidence of perianal disease is higher in SEA than in Australia and is comparable to the West. In a multiracial population, such as Singapore and Malaysia, Indians have the highest incidence and prevalence rates, which are likely to be due to important putative mutations. For instance, a higher frequency of the NOD2 predisposing mutation SNP5 and IBD risk allele IGR2198a and IGR2092a were found in Indians. Although differences in the genetic constitution play an important role in the epidemiology and prognosis of IBD in SEA, the emergence of this disease offers a unique opportunity to identify potential exposomes that contribute to its pathogenesis.

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.

Emerging inflammatory bowel disease demographics, phenotype, and treatment in South Asia, South-East Asia, and Middle East: Preliminary findings from the Inflammatory Bowel Disease-Emerging Nations' Consortium

BACKGROUND AND AIM

Inflammatory bowel disease (IBD) is emerging in the newly industrialized countries of South Asia, South-East Asia, and the Middle East, yet epidemiological data are scarce.

METHODS

We performed a cross-sectional study of IBD demographics, disease phenotype, and treatment across 38 centers in 15 countries of South Asia, South-East Asia, and Middle East. Intergroup comparisons included gross national income (GNI) per capita.

RESULTS

Among 10 400 patients, ulcerative colitis (UC) was twice as common as Crohn's disease (CD), with a male predominance (UC 6678, CD 3495, IBD unclassified 227, and 58% male). Peak age of onset was in the third decade, with a low proportion of elderly-onset IBD (5% age > 60). Familial IBD was rare (5%). The extent of UC was predominantly distal (proctitis/left sided 67%), with most being treated with mesalamine (94%), steroids (54%), or immunomodulators (31%). Ileocolic CD (43%) was the commonest, with low rates of perianal disease (8%) and only 6% smokers. Diagnostic delay for CD was common (median 12 months; interquartile range 5-30). Treatment of CD included mesalamine, steroids, and immunomodulators (61%, 51%, and 56%, respectively), but a fifth received empirical antitubercular therapy. Treatment with biologics was uncommon (4% UC and 13% CD), which increased in countries with higher GNI per capita. Surgery rates were 0.1 (UC) and 2 (CD) per 100 patients per year.

CONCLUSIONS

The IBD-ENC cohort provides insight into IBD in South-East Asia and the Middle East, but is not yet population based. UC is twice as common as CD, familial disease is uncommon, and rates of surgery are low. Biologic use correlates with per capita GNI.

Very early onset inflammatory bowel disease in a South Asian country where inflammatory bowel disease is emerging: a distinct clinical phenotype from later onset disease

BACKGROUND/AIMS

Information on pediatric inflammatory bowel disease (PIBD) and very early onset IBD (VEOIBD) are sparse in India, where IBD is emerging. We aimed to evaluate characteristics of VEOIBD and later onset PIBD (LO-PIBD) in India.

METHODS

We performed retrospective analysis of a large, prospectively maintained IBD registry. PIBD was divided in to VEOIBD ( < 6 years) and LO-PIBD (6-17 years). Demographic data, disease characteristics and treatment were compared between the PIBD groups and with other Asian/Western studies as well as the adult patients of the registry.

RESULTS

Of 3,752 IBD patients, 292 (7.8%) had PIBD (0-17 years) (175 Crohn's disease [CD], 113 ulcerative colitis [UC], 4 IBD-undifferentiated; 22 VEOIBD [7.5%], and 270 LO-PIBD [92.5%]). VEOIBD patients had more severe disease compared to LO-PIBD in both UC (P= 0.003) and CD (P< 0.001). Familial IBD was more common in VEOIBD (13.6%) compared to LO-PIBD (9.2%). Ileal disease (L1) was an independent risk factor for diagnostic delay in pediatric CD. Diagnostic delay ( > 6 months) was significantly lower in VEOIBD (40.9%) than in LO-PIBD (78.8%) (P< 0.001). Compared to other Asian and Western studies, extensive UC (72.5%) and complicated CD (stricturing/penetrating: 42.7%) were relatively more common. Perianal CD was relatively less frequent (7.4%). PIBD had a significantly higher number of complicated and ileal CD and extensive UC comparison to adult cohort of the registry.

CONCLUSIONS

VEOIBD has more aggressive phenotype than LO-PIBD. Disease appears distinct from other Asian and Western studies and adult onset disease, with more complicated CD and extensive UC.

Review article: distinctions between ileal and colonic Crohn's disease: from physiology to pathology

BACKGROUND

Ileal and colonic Crohn's disease seem to be two separate entities.

AIMS

To describe the main physiological distinctions between the small and the large intestine and to analyse the differences between ileal and colonic Crohn's disease.

METHODS

The relevant literature was critically examined and synthesised.

RESULTS

The small and large intestine have fundamental distinctions (anatomy, cellular populations, immune defence, microbiota). The differences between ileal and colonic Crohn's disease are highlighted by a heterogeneous body of evidence including clinical features (natural history of the disease, efficacy of treatments, and monitoring), epidemiological data (smoking status, age, gender) and biological data (genetics, microbiota, immunity, mesenteric fat). However, the contribution of these factors to disease location remains poorly understood.

CONCLUSION

The classification of ileal and colonic Crohn's disease as distinct subphenotypes is well supported by the literature. Understanding of these differences could be exploited to develop more individualised patient care.

Long-term Disease Course of Crohn's Disease: Changes in Disease Location, Phenotype, Activities, and Predictive Factors

Crohn's disease (CD) is a chronic destructive inflammatory bowel disease that affects young people and is associated with significant morbidity. The clinical spectrum and disease course of CD are heterogeneous and often difficult to predict based on the initial presentation. In this article, changes in the disease location, behavior, clinical course during long-term follow-up, and predictive factors are reviewed. Generally, four different patterns of clinical course are discussed: remission, stable disease, chronic relapsing disease, and chronic refractory disease. Understanding the long-term disease course of CD is mandatory to reveal the underlying pathophysiology of the disease and to move toward a more optimistic disease course, such as remission or stability, and less adverse outcomes or devastating sequelae.

Incidence of pediatric inflammatory bowel disease within the Vaccine Safety Datalink network and evaluation of association with rotavirus vaccination

BACKGROUND

Recent studies have reported an increase in Inflammatory bowel disease (IBD) incidence in young children, highlighting the need to better understand risk factors for the development of IBD. Licensed for use in infants in 2006, the oral, live-attenuated rotavirus vaccine has biologic plausibility for instigating inflammation of the gut mucosa as a pathway to immune dysregulation.

METHODS

Over a ten-year period, we evaluated incidence of IBD within a cohort of children under the age of ten, enrolled in seven integrated healthcare delivery systems. We conducted a nested case-control study to evaluate the association between rotavirus vaccination and IBD using conditional logistic regression. Cases were confirmed via medical record review and matched to non-IBD controls on date of birth, sex, and study site.

RESULTS

Among 2.4 million children under the age of 10 years, 333 cases of IBD were identified with onset between 2007 and 2016. The crude incidence of IBD increased slightly over the study period (p-value for trend = 0.046). Of the 333 cases, 227 (68%) were born prior to 2007. Forty-two cases born in 2007 or later, with continuous enrollment since birth were included in the case-control study and matched to 210 controls. The adjusted odds ratio for any rotavirus vaccination in IBD cases, compared to matched controls, was 0.72 (95% confidence interval 0.19-2.65).

CONCLUSIONS

Data from this large pediatric cohort demonstrate a small overall increase in IBD incidence in young children over a ten-year period. The data suggest that rotavirus vaccination is not associated with development of IBD.

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.

Familial aggregation of inflammatory bowel disease in India: prevalence, risks and impact on disease behavior

Background/Aims

Information about familial aggregation of inflammatory bowel disease (IBD) in Asia is limited. We aimed to analyze the prevalence and risk of familial IBD in an Indian cohort and compare familial and sporadic cases.

Methods

Familial IBD cases were identified from a large prospectively maintained IBD registry. The prevalence of IBD in first- and seconddegree relatives of index cases was evaluated. The disease behavior was compared to that of sporadic cases.

Results

Total 3,553 patients (ulcerative colitis [UC], 2,053; Crohn’s disease [CD], 1,500) were included. Familial IBD was noted in 4.13% of CD and 4.34% of UC patients. Family history was commoner in pediatric group (< 18 years) (P= 0.0002; odds ratio [OR], 2.8; 95% confidence interval [CI], 1.6–4.8). Majority had paternal transmission (UC, 67.42%; CD, 70.97%). Concordance of disease type was higher in UC (79.7%) compared to CD (37.1%). Familial IBD was associated with higher cumulative relapse rate (CD, P< 0.001; UC, P< 0.001), higher cumulative rate of surgery (CD, P< 0.001; UC, P< 0.001) and higher rate of biologic use (CD, P= 0.010; UC, P= 0.015). Pan-colitis was higher in familial UC (P= 0.003; OR, 1.935; 95% CI, 1.248–3.000). Fistulizing disease was commoner in familial CD (P= 0.041; OR, 2.044; 95% CI, 1.030–4.056).

Conclusions

The prevalence of familial IBD in India appears comparable to rest of Asia but lower than the West. It is associated with a younger age of onset, higher incidence of pan-colitis in UC and fistulizing complications in CD. Familial IBD has higher cumulative relapse, surgery and biologic use rates. Hence, family history of IBD could have important prognostic implications.

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

BACKGROUND AND AIM

Family history is the strongest risk factor for developing Crohn's disease [CD] or ulcerative colitis [UC]. We investigated whether the proximity of relationship with the affected relative and concordance for type of inflammatory bowel disease [IBD] modifies the effect of family history on phenotype and disease severity.

METHOD

This cross-sectional study included patients with a confirmed diagnosis of IBD in a clinical registry. Family history of IBD was assessed by a questionnaire ascertaining presence of disease in a first-first-degree, second-second-degree or distant relative. Our primary outcomes were disease phenotype as per the Montreal classification and severity measured by need for immunomodulator, biologic, or surgical therapy. Genotyping was performed on the Immunochip and faecal samples were subjected to 16S rRNA microbiome sequencing.

RESULTS

Our study included 2136 patients with IBD [1197 CD, 939 UC]. Just under one-third [32%] of cases ere familial IBD [17% first-degree, 21% second-degree]. Familial IBD was diagnosed at an earlier age, both in CD [26 vs 28 years, p = 0.0006] and UC [29 vs 32 years, p = 0.01]. Among CD patients, a positive family history for CD was associated with an increased risk for complicated disease in the presence of an affected family member (odds ratio [OR] 1.48, 95% confidence interval [CI] 1.07-2.03). However, this effect was significant only for first-degree relatives [OR 1.82, 95% CI 1.19-2.78].

CONCLUSIONS

A family history of CD in first-degree relatives was associated with complicated CD. Family history discordant for type of IBD or in distant relatives did not influence disease phenotype or natural history.

Specificities of presentation of Crohn's disease in childhood

The incidence of inflammatory bowel disease in the pediatric population has increased in the last years. The most common form of inflammatory bowel disease is Crohn's disease and, according to its form and age of presentation, it is possible to predict the evolution of the disease.

Familial and ethnic risk in inflammatory bowel disease

Familial aggregation in inflammatory bowel disease (IBD) has been established for several decades, reflecting shared genetic and environmental susceptibility. A positive family history remains the strongest recognizable risk factor for the development of IBD and is reported in around 8-12% of IBD patients. Crohn’s disease shows a more frequent familial pattern than ulcerative colitis. The risk of developing IBD in first-degree relatives of an affected proband is increased 4- to 8-fold. The risk for twins and children born from couples who both have IBD is also substantially higher; a cumulative effect of the number of family members affected has been described, with the highest incidence being described for families with three or more affected members. Herein, we review the available evidence regarding familial IBD, and briefly discuss the variation of IBD across different races and ethnicities, hoping to provide a useful update and a practical guide that can serve clinicians as a guide for counseling.

Disease severity and treatment requirements in familial inflammatory bowel disease

PURPOSE

Several studies demonstrate an increased prevalence and concordance of inflammatory bowel disease among the relatives of patients. Other studies suggest that genetic influence is over-estimated. The aims of this study are to evaluate the phenotypic expression and the treatment requirements in familial inflammatory bowel disease, to study the relationship between number of relatives and degree of kinship with disease severity and to quantify the impact of family aggregation compared to other environmental factors.

METHODS

Observational analytical study of 1211 patients followed in our unit. We analyzed, according to the existence of familial association, number and degree of consanguinity, the phenotypic expression, complications, extraintestinal manifestations, treatment requirements, and mortality. A multivariable analysis considering smoking habits and non-steroidal-anti-inflammatory drugs was performed.

RESULTS

14.2% of patients had relatives affected. Median age at diagnosis tended to be lower in the familial group, 32 vs 29, p = 0.07. In familial ulcerative colitis, there was a higher proportion of extraintestinal manifestations: peripheral arthropathy (OR = 2.3, p = 0.015) and erythema nodosum (OR = 7.6, p = 0.001). In familial Crohn's disease, there were higher treatment requirements: immunomodulators (OR = 1.8, p = 0.029); biologics (OR = 1.9, p = 0.011); and surgery (OR = 1.7, p = 0.044). The abdominal abscess increased with the number of relatives affected: 5.1% (sporadic), 7.0% (one), and 14.3% (two or more), p=0.039. These associations were maintained in the multivariate analysis.

CONCLUSIONS

Familial aggregation is considered a risk factor for more aggressive disease and higher treatment requirements, a tendency for earlier onset, more abdominal abscess, and extraintestinal manifestations, remaining a risk factor analyzing the influence of some environmental factors.

Crohn's Disease of the Colon, Rectum, and Anus

There is no cure for Crohn disease. Newer treatments, such as biological therapy, have led to an improved quality of life. This article focuses on the surgical management of Crohn disease of the colon, rectum, and anus. Restorative and nonrestorative surgical options for colonic Crohn disease are discussed. Treatment options for perianal Crohn disease are also reviewed.

Inflammatory bowel disease

Scandinavian researchers have contributed to the present understanding of inflammatory bowel disease (IBD). Important epidemiological data and family risk factors have been reported from all the Nordic countries, original twin studies mainly from Denmark and Sweden, and relationships to cancer and surgery mostly from Sweden. In collaboration with the industry, development of medical compounds was for a long time in the front line of international research, and the Scandinavian countries participated in the clinical breakthrough of biologic treatment. At present, many Nordic centers are working in the forefront of IBD research. An increasing number of young investigators have entered the scene along with the extended distribution of University clinics and research laboratories in these countries. This presentation of IBD gives a brief overview in the fields of clinical epidemiology and molecular biology. Many areas are covered by International collaborations with partners from Nordic centers. IBD was a topic focused by the founders of Scandinavian Journal of Gastroenterology. After 50 years one may state that the journal's history reflects important pieces of scientific knowledge within these diseases. The early scope of Johannes Myren for IBD was shown through his work in the original World Association of Gastroenterology (OMG), and after 50 years we can clearly support the view that global perspectives in IBD are increasingly important.

Identification of risk loci for Crohn's disease phenotypes using a genome-wide association study

BACKGROUND & AIMS

Crohn's disease is a highly heterogeneous inflammatory bowel disease comprising multiple clinical phenotypes. Genome-wide association studies (GWASs) have associated a large number of loci with disease risk but have not associated any specific genetic variants with clinical phenotypes. We performed a GWAS of clinical phenotypes in Crohn's disease.

METHODS

We genotyped 576,818 single-nucleotide polymorphisms in a well-characterized cohort of 1090 Crohn's disease patients of European ancestry. We assessed their association with 17 phenotypes of Crohn's disease (based on disease location, disease behavior, disease course, age at onset, and extraintestinal manifestations). A total of 57 markers with strong associations to Crohn's disease phenotypes (P < 2 × 10(-4)) were subsequently analyzed in an independent replication cohort of 1296 patients of European ancestry.

RESULTS

We replicated the association of 4 loci with different Crohn's disease phenotypes. Variants in MAGI1, CLCA2, 2q24.1, and LY75 loci were associated with a complicated stricturing disease course (Pcombined = 2.01 × 10(-8)), disease location (Pcombined = 1.3 × 10(-6)), mild disease course (Pcombined = 5.94 × 10(-7)), and erythema nodosum (Pcombined = 2.27 × 10(-6)), respectively.

CONCLUSIONS

In a GWAS, we associated 4 loci with clinical phenotypes of Crohn's disease. These findings indicate a genetic basis for the clinical heterogeneity observed for this inflammatory bowel disease.

Family history of inflammatory bowel disease among patients with ulcerative colitis: a systematic review and meta-analysis

BACKGROUND AND AIMS

Despite numerous shared susceptibility loci between Crohn's disease and ulcerative colitis, the prevalence of family history among ulcerative colitis patients is not well-established and considered to be less prevalent. A systemic review and meta-analysis were conducted to estimate the prevalence of family history of inflammatory bowel disease in ulcerative colitis patients, and its effect on disease outcomes.

METHODS

PubMED was searched to identify studies reporting the prevalence of family history of inflammatory bowel disease among ulcerative colitis patients. Definitions of family history, study type, and subtypes of family history prevalence were abstracted, as were disease outcomes including age at ulcerative colitis diagnosis, disease location, surgery and extraintestinal manifestations. Pooled prevalence estimates were calculated using random effects models.

RESULTS

Seventy-one studies (86,824 patients) were included. The prevalence of a family history of inflammatory bowel disease in ulcerative colitis patients was 12% (95% confidence interval [CI] 11 to 13%; range 0-39%). Family history of ulcerative colitis (9%; 22 studies) was more prevalent than Crohn's disease (2%; 18 studies). Patients younger than 18years of age at time of diagnosis had a greater family history of inflammatory bowel disease (prevalence 15%, 95% CI: 11-20%; 13 studies). There were no differences in disease location, need for surgery, or extraintestinal manifestations among those with a family history, although very few studies reported on these outcomes.

CONCLUSIONS

Overall, 12% of ulcerative colitis patients have a family history of inflammatory bowel disease, and were more likely to have a family history of ulcerative colitis than Crohn's disease. Pediatric-onset ulcerative colitis patients were more likely to have a family history of inflammatory bowel disease.

The association between race and Crohn's disease phenotype in the Western Cape population of South Africa, defined by the Montreal Classification System

Background

Inter-racial differences in disease characteristics and in the management of Crohn's disease (CD) have been described in African American and Asian subjects, however for the racial groups in South Africa, no such recent literature exists.

Methods

A cross sectional study of all consecutive CD patients seen at 2 large inflammatory bowel disease (IBD) referral centers in the Western Cape, South Africa between September 2011 and January 2013 was performed. Numerous demographic and clinical variables at diagnosis and date of study enrolment were identified using an investigator administered questionnaire as well as clinical examination and patient case notes. Using predefined definitions, disease behavior was stratified as ‘complicated’ or ‘uncomplicated’.

Results

One hundred and ninety four CD subjects were identified; 35 (18%) were white, 152 (78%) were Cape Coloured and 7(4%) were black. On multiple logistic regression analysis Cape Coloureds were significantly more likely to develop ‘complicated’ CD (60% vs. 9%, p = 0.023) during the disease course when compared to white subjects. In addition, significantly more white subjects had successfully discontinued cigarette smoking at study enrolment (31% vs. 7% reduction, p = 0.02). No additional inter-racial differences were found. A low proportion of IBD family history was observed among the non-white subjects.

Conclusions

Cape Coloured patients were significantly more likely to develop ‘complicated’ CD over time when compared to whites.

Phenotypic concordance in familial inflammatory bowel disease (IBD). Results of a nationwide IBD Spanish database

BACKGROUND & AIMS

Disease outcome has been found to be poorer in familial inflammatory bowel disease (IBD) than in sporadic forms, but assessment of phenotypic concordance in familial IBD provided controversial results. We assessed the concordance for disease type and phenotypic features in IBD families.

METHODS

Patients with familial IBD were identified from the IBD Spanish database ENEIDA. Families in whom at least two members were in the database were selected for concordance analysis (κ index). Concordance for type of IBD [Crohn's disease (CD) vs. ulcerative colitis (UC)], as well as for disease extent, localization and behaviour, perianal disease, extraintestinal manifestations, and indicators of severe disease (i.e., need for immunosuppressors, biological agents, and surgery) for those pairs concordant for IBD type, were analyzed.

RESULTS

798 out of 11,905 IBD patients (7%) in ENEIDA had familial history of IBD. Complete data of 107 families (231 patients and 144 consanguineous pairs) were available for concordance analyses. The youngest members of the pairs were diagnosed with IBD at a significantly younger age (p<0.001) than the oldest ones. Seventy-six percent of pairs matched up for the IBD type (κ=0.58; 95%CI: 0.42-0.73, moderate concordance). There was no relevant concordance for any of the phenotypic items assessed in both diseases.

CONCLUSIONS

Familial IBD is associated with diagnostic anticipation in younger individuals. Familial history does not allow predicting any phenotypic feature other than IBD type.

Prediction of Crohn’s disease aggression through NOD2/CARD15 gene sequencing in an Australian cohort

AIM: To investigate the association between mutations in oligomerisation domain 2/caspase recruitment domains 15 (NOD2/CARD15) and the natural history of Crohn’s disease (CD) to identify patients who would benefit from early aggressive medical intervention.

METHODS: We recruited thirty consecutive unrelated CD patients with a history of ileo-caecal or small bowel resection during the period 1980-2000; Fifteen patients of these had post-operative relapse that required further surgery and fifteen did not. Full sequencing of the NOD2/CARD15 gene using dHPLC for exons 3, 5, 7, 10 and 12 and direct sequencing for exons 2, 4, 6, 8, 9 and 11 was conducted. CD patients categorized as carrying variants were anyone with at least 1 variant of the NOD2/CARD15 gene.

RESULTS: About 13.3% of the cohort (four patients) carried at least one mutant allele of 3020insC of the NOD2/CARD15 gene. There were 20 males and 10 females with a mean age of 43.3 years (range 25-69 years). The mean follow up was 199.6 mo and a median of 189.5 mo. Sixteen sequence variations within the NOD2/CARD15 gene were identified, with 9 of them occurring with an allele frequency of greater than 10 %. In this study, there was a trend to suggest that patients with the 3020insC mutation have a higher frequency of operations compared to those without the mutation. Patients with the 3020insC mutation had a significantly shorter time between the diagnosis of CD and initial surgery. This study included Australian patients of ethnically heterogenous background unlike previous studies conducted in different countries.

CONCLUSION: These findings suggest that patients carrying NOD2/CARD15 mutations follow a rapid and more aggressive form of Crohn’s disease showing a trend for multiple surgical interventions and significantly shorter time to early surgery.

The influence of CTGF single-nucleotide polymorphisms on outcomes in Crohn's disease

OBJECTIVE

To examine the association between single-nucleotide polymorphisms (SNPs) in CTGF (connective tissue growth factor) and patient outcomes after terminal ileal resection for Crohn's disease.

BACKGROUND

The primary indication for intestinal resection in Crohn's disease is fibrostenotic terminal ileal disease. CTGF is a cytokine overexpressed in the intestine of patients with Crohn's disease that influences outcomes in other disease processes.

METHODS

DNA was extracted from formalin-fixed, paraffin-embedded tissue from 147 patients with Crohn's disease who had undergone terminal ileal resection between 1981 and 2009. Genotyping was performed for 4 CTGF SNPs (rs9402373, rs12526196, rs6918698, and rs9399005), which modulate nuclear factor binding and CTGF production, and a smad3 SNP (rs17293632) involved in the CTGF pathway. Patients were phenotyped using the Montreal Disease Classification.

RESULTS

Sixty-seven of 147 patients (45.6%) were male; the mean age at diagnosis was 30.3 ± 12.6 years and the mean follow-up duration was 8.3 ± 7.1 years. Genotype-phenotype analysis demonstrated that the rs6918698GG genotype was associated with an older age of disease onset [>40 years; 30.6% vs 13.2%; odds ratio (OR): 2.891; 95% confidence interval (CI): 1.170-7.147). The rs9402373CC genotype was positively associated with type B1 disease (50.7% vs 26.3%; OR: 2.876; 95% CI: 1.226-6.743) and negatively associated with B2 disease (37.0% vs 65.0%; OR: 0.317; 95% CI: 0.144-0.699). None of the 5 SNPs assessed influenced clinical or surgical recurrence of Crohn's disease after intestinal resection. On multivariate analysis, male sex odds ratio (OR): 0.235; 95% CI: 0.073-0.755; P = 0.015] and never having smoked tobacco (OR: 0.249; 95% CI: 0.070-0.894; P = 0.033) reduced the risk, whereas having a prior appendectomy increased the risk (OR: 5.048; 95% CI: 1.632-15.617; P = 0.005) of surgical recurrence.

CONCLUSIONS

These data implicate the rs6918698GG genotype with an age of disease onset of greater than 40 years in Crohn's disease whereas the rs9402373CC genotype is associated with a nonstricturing, nonpenetrating disease phenotype. CTGF SNPs do not influence the rate of recurrence after terminal ileal resection for Crohn's disease.

The effect of NOD2 polymorphism on postsurgical recurrence in Crohn's disease: a systematic review and meta-analysis of available literature

BACKGROUND

Up to 70% of patients requiring surgery for Crohn's disease (CD) develop recurrence within 10 years. Unequivocal markers predicting recurrence are needed to tailor postoperative therapy appropriately. NOD2 (nucleotide-binding oligomerization domain 2) polymorphisms increase the risk of developing CD; however, their ability to predict recurrence is uncertain. This study aims to determine the association between NOD2 variants and surgical recurrence after initial disease-modifying surgery.

METHODS

A comprehensive search for published series comparing the effect of NOD2 polymorphisms on postoperative surgical recurrence in patients with CD was performed. Random-effects methods were used to combine data.

RESULTS

Six cohort studies comprising 1003 patients with CD were included. A total of 340 patients (33.9%) expressed at least 1 of the 3 common NOD2 polymorphisms. The 1003 patients underwent surgical resection with 335 (33%) developing surgical recurrence. Of 340 NOD2-expressing patients, 130 (39%) required further resection, whereas 202 of 663 patients (30.5%) without the variant underwent repeat resection. NOD2 was not significantly associated with surgical recurrence (odds ratio: 1.58, 95% confidence interval: 0.97-2.57, P = 0.064), most likely because of study heterogeneity (Cochran Q: 12.36, P = 0.030, I: 59.6%). The sensitivity of any mutation in predicting disease recurrence was 39.7% and specificity was 69%, with the area under the receiver operating characteristic curve being 0.64.

CONCLUSIONS

Patients with CD with a NOD2 polymorphism do not have an increased risk of surgical recurrence compared with patients without the variant. These data provide insufficient evidence to support postoperative medical prophylaxis based solely on the presence of NOD2 polymorphism.

Inflammatory bowel disease in Asia: a systematic review

The incidence and prevalence of inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC), are lower in Asia than in the West. However, across Asia the incidence and prevalence of IBD has increased rapidly over the last two to four decades. These changes may relate to increased contact with the West, westernization of diet, increasing antibiotics use, improved hygiene, vaccinations, or changes in the gut microbiota. Genetic factors also differ between Asians and the Caucasians. In Asia, UC is more prevalent than CD, although CD incidence is rapidly increasing in certain areas. There is a male predominance of CD in Asia, but a trend towards equal sex distribution for UC. IBD is diagnosed at a slightly older age than in the West, and there is rarely a second incidence peak as in the West. A positive family history is much less common than in the West, as are extra-intestinal disease manifestations. There are clear ethnic differences in incidence within countries in Asia, and an increased incidence in IBD in migrants from Asia to the West. Research in Asia, an area of rapidly changing IBD epidemiology, may lead to the discovery of critical etiologic factors that lead to the development of IBD.

Role of genetic and environmental factors in British twins with inflammatory bowel disease

BACKGROUND

Twin studies provide insight into the complex interaction between genetic and environmental factors in the development of inflammatory bowel disease (IBD). We assessed associations between childhood environmental factors and development of Crohn's disease (CD) and ulcerative colitis (UC) in twins.

METHODS

Questionnaires on clinical demographics and exposure to environmental factors were sent to twins with IBD, their healthy co-twins, and their doctors. Kappa statistics were used to examine agreement between twin pairs and odds ratios were calculated by conditional logistic regression.

RESULTS

In all, 250 IBD twin pairs (122 CD; 125 UC; 3 CD/UC; 28 concordant pairs) were analyzed. Concordant monozygotic twins with CD showed good agreement for disease location (κ 0.88; 95% confidence interval [CI]: 0.45-1.00), disease behavior (κ 1.00; 95% CI: 0.43-1.00), and moderate agreement for age at diagnosis and need for medical and surgical therapy. Concordant monozygotic twins with UC showed good agreement for disease extent (κ 0.60; CI 0.13-1.00) and use of thiopurines (κ 0.73; CI 0.10-1.00). In discordant twins, symptomatic childhood mumps infection (odds ratio [OR], 3.8; 95% CI, 1.2-11.3) and oral contraceptives (OR, 4.0; 1.1-14.2) were associated with CD. Smoking was associated with CD (OR, 4.3; 95% CI, 1.9-9.8) but inversely associated with UC (OR, 0.3; 95% CI, 0.1-0.9). Both CD and UC twins had suffered more "gastroenteritis" and spent more time with animals than their co-twins.

CONCLUSIONS

Disease phenotype in CD and disease extent in UC appeared to be genetically influenced. Smoking is a risk factor for CD but is protective for UC. Early exposure to "infections" during childhood may be associated with the development of IBD.

Chronic nonspecific multiple ulcer of the small intestine segregates in offspring from consanguinity

BACKGROUND AND AIMS

Chronic nonspecific multiple ulcer of the small intestine is a recently proposed enteropathy characterized by persistent blood and protein loss from the small-bowel. We examined possible segregation of the disease in family pedigrees.

METHODS

All cases of the disease diagnosed at our institution were reviewed with respect to particular focuses on the presence of close consanguinity in the families, the enteroscopic findings and the long-term clinical course. The diagnosis was based on persistent occult gastrointestinal bleeding and hypoproteinemia for more than 5 years, and irregularly shaped shallow ulcers in the ileum.

RESULTS

During a 45-year-period, 13 patients were diagnosed as having the disease. There were 11 females and 2 males, with ages ranging from 8 to 37 years at the time of the initial presentation and with those from 13 to 38 years at the diagnosis. Enteroscopy performed in 11 patients with a time duration ranging from 0.5 to 44 years after the diagnosis revealed active ileal ulcers in 10 patients. Parents' consanguineous marriage was verified in 6 patients, two of whom also had siblings with the enteropathy. Another patient without consanguinity had a sibling with protein-losing enteropathy.

CONCLUSION

Chronic nonspecific multiple ulcer of the small intestine seems to segregate in offspring from consanguineous marriage.

Familial aggregation in inflammatory bowel disease: Is it genes or environment?

Inflammatory bowel disease (IBD) develops in genetically susceptible individuals due to the influence of environmental factors, leading to an abnormal recognition of microbiota antigens by the innate immune system which triggers an exaggerated immune response and subsequent bowel tissue damage. IBD has been more frequently found in families, an observation that could be due to either genetic, environmental or both types of factors present in these families. In addition to expanding our knowledge on IBD pathogenesis, defining the specific contribution to familial IBD of each one of these factors might have also clinical usefulness. We review the available evidence on familial IBD pathogenesis.

Prevalence of irritable bowel syndrome (IBS) in first-degree relatives of patients with inflammatory bowel disease (IBD)

BACKGROUND

Epidemiological studies have shown a greater prevalence of irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) among first-degree relatives of patients diagnosed of these diseases. However, it is not known whether relatives of patients with IBD have a greater prevalence of IBS than the general population.

AIMS

To analyse the prevalence of IBS among first-degree relatives by consanguinity (parents, siblings and offspring) and affinity (spouses) of patients with IBD.

MATERIALS AND METHODS

A prevalence study was conducted identifying 490 relatives of 91 patients with IBD. Of these, 404 met inclusion criteria; and 360 (response rate: 89.1%) answered the questionnaires. Subjects were invited to participate in the study through index cases (patients with IBD). The following variables were collected: age, sex, history of digestive diseases, kinship and cohabitation with the index case. The relatives completed a questionnaire to identify those who met Rome I and Rome II criteria for IBS.

RESULTS

The overall prevalence of IBS among the first-degree relatives of patients with IBD was 49.4% and 10% according to Rome I and Rome II criteria respectively. IBS prevalence was higher in first-degree blood relatives than in spouses of patients (Rome I: 53.1% vs 29.1%, p=0.001; Rome II: 10.8% vs 5.4%, NS). No differences were found in IBS prevalence depending on whether relatives were living with the index case or not.

CONCLUSION

IBS prevalence in first-degree relatives of patients with IBD is elevated. It is significantly greater in blood relatives, which suggests involvement of genetic and psychological factors rather than environmental factors.

NOD2 mutations and anti-Saccharomyces cerevisiae antibodies are risk factors for Crohn's disease in African Americans

OBJECTIVES

NOD2 mutations and anti-Saccharomyces cerevisiae antibodies (ASCAs) are established risk factors of Crohn's disease (CD) in whites but have not been assessed in African-American (AA) adults with CD.

METHODS

AAs with CD and controls were recruited by the Mid-Atlantic African-American IBD Study as part of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) IBD Genetics Consortium. Genotyping for the three common CD NOD2 mutations (Leu1007fsinsC, G908R/2722g>c, and R702W/2104c>t) and ASCA enzyme-linked immunosorbent assays were performed in 183 AA CD patients and in 143 controls. Logistic regression was used to calculate adjusted odds ratios (ORs) for the association between ASCA and disease phenotype.

RESULTS

ASCA sensitivity and specificity values were 70.5 and 70.4%, respectively. On univariate analysis, ASCA was significantly associated with younger age at diagnosis, ileal involvement, and complicated (stricturing/penetrating) behavior. On multivariate analysis, ASCA titer (per 25 Units) was associated with ileal involvement (OR 1.18, 95% confidence interval (CI): 1.04-1.34), complicated behavior (OR 1.13, 95% CI: 1.01-1.28), and surgery (hazard ratio: 1.11, 95% CI: 1.02-1.21). Cigarette smoking and CD family history were also significantly associated with surgery. NOD2 carriers (all heterozygotes) were more common among CD cases than controls (8.2 vs. 2.1%; OR 4.17%, 95% CI: 1.18-14.69). The NOD2 mutation population attributable risk was 6.2%.

CONCLUSIONS

In comparison with whites, ASCA in AAs has a similar sensitivity but a lower specificity for CD. ASCA is associated with ileal involvement, complicated behavior, and surgery in AAs with CD. NOD2 is a risk gene for AA CD, although mutation frequency and population attributable risk are much lower than in whites.

Familial aggregation and antimicrobial response dose-dependently affect the risk for Crohn's disease

BACKGROUND

An increased risk of Crohn's disease (CD) has been reported consistently in first-degree relatives of patients. Our aim was to test whether a combination of CD-associated genes involved in innate immunity and/or antibody responses to microbial antigens may be valuable in identifying healthy relatives at risk.

METHODS

We investigated 86 families from Belgium and northern France, 45 with at least 3 first-degree relatives with CD, 24 with a single case, and 17 control families without inflammatory bowel disease (IBD). The cohort consisted of 186 CD patients, 290 healthy relatives, and 142 controls (total 618). Genetic (NOD2, NOD1, TLR4, CARD8) and serologic markers (ASCA, ACMA, ALCA, ACCA, ASigmaMA, OmpC, CBir1, I2) were determined in all subjects. All Belgian families were prospectively followed up for 54 months.

RESULTS

In multiple-affected families, an increment of affected first-degree relatives and of positive antibodies were additive risks factors for CD (P < 0.0001), independent of NOD2 mutations. When comparing subjects from multiple-affected families, having 3 additional first-degree relatives with CD and 1 additional positive antibody increased the odds for CD to 9.19 (95% confidence interval [CI]: 4.07-20.80). After a follow-up of 54 months among all Belgian families, a total of 4 new diagnoses of IBD were confirmed in the multiple-affected families only, resulting in a 57-fold increase in incidence within multiple-affected families compared to the known incidence of IBD in our region.

CONCLUSIONS

We found an additive risk increment for CD in subjects from multicase families per additional affected relative and per additional positive antibody, independent of NOD2. Furthermore, a very high disease incidence was observed in these multiple-affected families.

Update on genetics in inflammatory disease

Crohn's disease and ulcerative colitis are chronic inflammatory disorders caused by a disruptive interaction between the immune system and gut luminal factors. Although the exact aetiology of IBD remains unclear, accumulating data, including genome-wide association studies (GWAS), have advanced our understanding of the immunopathogenesis. This review highlights the role in gut homeostasis and IBD pathogenesis. It focuses on past and recent advances in our understanding of IBD, including genetics and immunobiology. Recently published GWAS have confirmed earlier findings related to the NOD2 gene and the IBD5 locus. In addition, over 30 novel loci have been identified. Several promising associations between Crohn's disease and gene variants have been identified and replicated, the two most widely replicated being variants in the IL23R and ATG16L1 genes. These findings highlight and further support the importance of the immune system and its interactions with the intestinal flora in the pathogenesis of inflammatory bowel disease.

Epidemiology of inflammatory bowel disease in a German twin cohort: results of a nationwide study

BACKGROUND

Genetic predisposition as a cause of inflammatory bowel disease (IBD) has been proven by both family and twin studies and genetic variants associated with the disease have been identified. The aim of our study was to determine the concordance rates for IBD in German twin pairs and to evaluate clinical characteristics of concordant and discordant twin pairs.

METHODS

Patients with IBD were asked to participate and complete a questionnaire that contained questions about zygosity, demographic data, and medical history.

RESULTS

A total of 189 twin pairs in which at least 1 member had IBD were recruited (68 monozygotic and 121 dizygotic pairs). Within monozygotic pairs, 11 out of 31 (35%) were concordant for Crohn's disease (CD) and 6 out of 37 (16%) for ulcerative colitis (UC). Two of the 58 (3%) dizygotic pairs with CD and 1 out of 63 (2%) dizygotic pairs with UC were concordant for the disease. In 14 out of 20 (70%) discordant monozygotic CD pairs and 25 out of 31 (81%) discordant monozygotic pairs with UC, the first-born was affected by IBD. For discordant dizygotic twins, the first in birth order had IBD in 33 out of 56 (59%) pairs with CD and 40 out of 62 (64.5%) pairs with UC.

CONCLUSIONS

This study confirms a stronger genetic influence in CD than in UC. The high preponderance in being affected of the first-born twin and the fact that concordance was only 35% for CD and 16% for UC monozygotic twins highlight the important role of environmental trigger factors.

Testing concordance of clinical characteristics in familial studies with application to inflammatory bowel diseases

The etiology of chronic Inflammatory Bowel Diseases (IBD) remains unknown, with both genetic and environmental risk factors having been implicated. A recent collaborative study of IBD provides clinical data from families with three or more affected first-degree relatives. The scientific question is whether specific clinical characteristics aggregate among affected individuals within families. Gastroenterological researchers have examined the number of concordant familial pairs in familial aggregation studies, but methods and results have been discrepant. This article investigates concepts of concordance and gives a comprehensive statistical treatment for testing concordance of various clinical traits in familial studies. For dichotomous traits, the distribution of this statistic under the null hypothesis of no familial aggregation is obtained by three methods: asymptotic, probability generating function, and permutation. The permutation method is extended to analyze aggregation for non-dichotomous traits and co-aggregations between two traits. We apply the permutation method to analyze the aforementioned multiply-affected IBD family data. Evidence is found for familial clustering of various traits, some of which are not revealed in existing studies. Such analyses provide a basis for investigating the dependence of trait aggregation upon genetic or environmental risk factors.

Longitudinal concordance for clinical characteristics in a Swedish-Danish twin population with inflammatory bowel disease

BACKGROUND

The genetic influence on disease course in inflammatory bowel disease (IBD) remains unknown. We therefore aimed to study longitudinal concordance for clinical characteristics and longitudinal stability using the Montreal Classification in an IBD twin population.

METHODS

A total of 158 twins with ulcerative colitis (UC) (18 belonging to 9 concordant monozygotic pairs) and 141 twins with Crohn's disease (CD) (34 belonging to 17 concordant monozygotic pairs) were enrolled. Medical notes were scrutinized for clinical characteristics at diagnosis and after 10 years. Using the binominal distribution, we tested the hypothesis that clinical characteristics were independent within individuals in disease concordant monozygotic pairs.

RESULTS

In CD, location was identical in 11/17 monozygotic concordant pairs at diagnosis (P = 0.008) and in 11/16 pairs after 10 years (P = 0.02). Behavior at diagnosis was identical in 13/17 pairs (P = 0.03) and in 11/16 pairs after 10 years (P = 0.01). Monozygotic UC twins were concordant (within 5 years) for age at diagnosis (6/9 pairs; P < 0.001) and symptomatic onset (4/9 pairs; P = 0.02) but not for extent of disease at diagnosis or after 10 years. The Montreal Classification did not demonstrate longitudinal stability, either regarding location or behavior of CD or extent of UC.

CONCLUSIONS

The high phenotypic concordance, both at diagnosis and longitudinally, in monozygotic twins with CD supports a genetic influence not only on disease occurrence but also on disease course. This contrasts with UC, where the genetic impact appears less. Montreal Classification characteristics changed over time and should be used cautiously.

Genome-wide gene expression differences in Crohn's disease and ulcerative colitis from endoscopic pinch biopsies: insights into distinctive pathogenesis

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) are inflammatory bowel diseases (IBD) with variable, overlapping clinical features and complex pathophysiologies.

METHODS

To identify pathogenic processes underlying these disease subtypes, we used single endoscopic pinch biopsies to elucidate patterns of gene expression in active and inactive areas of UC and CD and compared these to infectious colitis and healthy control samples.

RESULTS

Unsupervised classification of a total of 36 samples yielded promising separation between the affected IBD, unaffected IBD, non-IBD colitis, and normal control samples, suggesting each sample type had a distinctive gene expression pattern. Genes differentially expressed in the CD samples compared to in the controls were related to IFNgamma-inducible TH1 processes (IFITM1, IFITM3, STAT1, and STAT3) and antigen presentation (TAP1, PSME2, PSMB8). The most noticeable change in the UC samples was reduced expression of genes regulating biosynthesis, metabolism, and electrolyte transport (HNF4G, KLF5, AQP8, ATP2B1, and SLC16A). Twenty-five percent of genes down-regulated in the UC samples were also down-regulated in the infectious colitis samples. Unaffected biopsy samples of IBD patients also registered differences expression of genes compared to in the normal controls. Of these differentially expressed genes, only 2 were up-regulated, PSKH1, a regulator of mRNA processing, and PPID, a suppressor of apoptosis.

CONCLUSIONS

The study shows that the gene expression patterns of IBD, CD in particular, are quite different from those of infectious colitis, highlighting distinctive expression of genes and pathways in UC and CD.

CARD15 mutations in Dutch familial and sporadic inflammatory bowel disease and an overview of European studies

OBJECTIVES

The single nucleotide variations R702W, G908R and L1007fs in the CARD15 gene have been found to be independently associated with Crohn's disease. The aim of this study was to evaluate the prevalence of these gene variations in Dutch multiple inflammatory bowel disease-affected families, in sporadic inflammatory bowel disease patients and in healthy controls.

METHODS

Dutch Caucasians from multiple inflammatory bowel disease-affected families were recruited, including 78 probands with Crohn's disease, 34 probands with ulcerative colitis and 71 inflammatory bowel disease-affected and 100 non-affected family members. In addition, 45 sporadic inflammatory bowel disease patients (36 Crohn's disease and nine ulcerative colitis), and 77 unrelated healthy controls were included. Genomic DNA was isolated to determine CARD15 R702W, G908R and L1007fs. For these mutations, we evaluated disease susceptibility and correlation with inflammatory bowel disease phenotypes.

RESULTS

In all included unrelated inflammatory bowel disease-affected probands, the R702W, G908R and L1007fs allele frequencies were 8.8, 6.1 and 11.0%, respectively, for Crohn's disease, and 4.7, 0 and 2.3% for ulcerative colitis. In controls, the allele frequencies were 5.9, 0.7 and 1.9%, respectively. G908R and L1007fs were associated with Crohn's disease (P=0.006 and 0.001, respectively). Compound heterozygotes for any of the three mutations were 11 (9.2%) in Crohn's disease patients, but none in ulcerative colitis patients nor controls. Carriage of CARD15 mutations was not associated with familial disease (P>or=0.38). Inflammatory bowel disease-affected family members of Crohn's disease probands carrying L1007fs, however, were carriers significantly more often than expected (P<0.001). In Crohn's disease patients, a significant trend was found between carriage of at least one CARD15 mutation and between carriage of L1007fs and behaviour of disease, including more carriers with stricturing and even more with penetrating disease (P=0.006 and 0.017, respectively).

CONCLUSION

In the Dutch population, CARD15 G908R and L1007fs are associated with Crohn's disease. Although no difference was found between sporadic and familial cases, in L1007fs-positive multiple affected families the inflammatory bowel disease-affected relatives are more likely than expected to carry this mutation. In Crohn's disease, carriage of at least one CARD15 mutation is associated with a more complicated disease behaviour.

Genome-wide association study identifies new susceptibility loci for Crohn disease and implicates autophagy in disease pathogenesis

We present a genome-wide association study of ileal Crohn disease and two independent replication studies that identify several new regions of association to Crohn disease. Specifically, in addition to the previously established CARD15 and IL23R associations, we identified strong and significantly replicated associations (combined P < 10(-10)) with an intergenic region on 10q21.1 and a coding variant in ATG16L1, the latter of which was also recently reported by another group. We also report strong associations with independent replication to variation in the genomic regions encoding PHOX2B, NCF4 and a predicted gene on 16q24.1 (FAM92B). Finally, we demonstrate that ATG16L1 is expressed in intestinal epithelial cell lines and that functional knockdown of this gene abrogates autophagy of Salmonella typhimurium. Together, these findings suggest that autophagy and host cell responses to intracellular microbes are involved in the pathogenesis of Crohn disease.

Genome-wide association study identifies new susceptibility loci for Crohn disease and implicates autophagy in disease pathogenesis

We present a genome-wide association study of ileal Crohn disease and two independent replication studies that identify several new regions of association to Crohn disease. Specifically, in addition to the previously established CARD15 and IL23R associations, we identified strong and significantly replicated associations (combined P < 10(-10)) with an intergenic region on 10q21.1 and a coding variant in ATG16L1, the latter of which was also recently reported by another group. We also report strong associations with independent replication to variation in the genomic regions encoding PHOX2B, NCF4 and a predicted gene on 16q24.1 (FAM92B). Finally, we demonstrate that ATG16L1 is expressed in intestinal epithelial cell lines and that functional knockdown of this gene abrogates autophagy of Salmonella typhimurium. Together, these findings suggest that autophagy and host cell responses to intracellular microbes are involved in the pathogenesis of Crohn disease.

Antibodies to saccharomyces cerevisiae in Crohn's disease: higher titers are associated with a greater frequency of mutant NOD2/CARD15 alleles and with a higher probability of complicated disease

BACKGROUND

Both antibodies to Saccharomyces cerevisiae (ASCA) and carriage of two mutated NOD2/CARD15 alleles are associated with ileal Crohn's disease (CD) and complications requiring bowel surgery. We assessed the ASCA titer as a marker of CD clinical behavior.

METHODS

In a cross-sectional study, we phenotyped 117 unrelated CD patients. Titers (Units, U) of ASCA IgG and IgA were measured and patients were genotyped for three high-risk NOD2/CARD15 alleles. Multiple logistic regression and Cox regression analyses were used to assess the association of factors to CD phenotype and time to surgery.

RESULTS

ASCA seropositivity was associated with younger age at diagnosis, ileal disease, and complicated (stricturing or penetrating) behavior. There was a dose-response between the number of mutant NOD2/CARD15 alleles and the prevalence and titers of ASCA. The ASCA titer and tobacco use were associated with ileal disease independently of NOD2/CARD15 status. The ASCA titer (odds ratio (OR): 2.7 per 25 U, 95% confidence interval (CI): 1.5-46.7) and ileal disease were associated with stricturing/penetrating behavior, independently of NOD2/CARD15 status. Patients with ileal CD and ASCA titers of 41 U and 60 U needed 10 and 5 years of disease, respectively, to accumulate a 50% risk of complications.

CONCLUSIONS

ASCA+ patients had a greater frequency of mutant NOD2/CARD15 alleles. Nonetheless, higher ASCA titers were associated with higher probabilities of ileal CD and stricturing/penetrating behavior independently of NOD2/CARD15 status. Higher ASCA titers were associated with more rapid development of complications. This quantitative marker may prove useful in risk-stratifying patients to more aggressive antiinflammatory therapies.

Molecular pathogenesis of inflammatory bowel disease: genotypes, phenotypes and personalized medicine

Crohn's disease (CD) and ulcerative colitis (UC), also known as inflammatory bowel diseases (IBD), are characterized by chronic inflammation of the gastrointestinal tract. IBD is among the few complex diseases for which several genomic regions and specific genes have been identified and confirmed in multiple replication studies. We will review the different loci implicated in disease risk in the context of three proposed mechanisms leading to chronic inflammation of the gut mucosa: 1) deregulation of the innate immune response to enteric microflora or pathogens; 2) increased permeability across the epithelial barrier; and 3) defective regulation of the adaptive immune system. As our knowledge of genetic variation, analytical approaches and technology improves, additional genetic risk factors are expected to be identified. With the identification of novel risk variants, additional pathophysiological mechanisms are likely to emerge. The resulting discoveries will further our molecular understanding of IBD, potentially leading to improved disease classification and rational drug design. Moreover, these approaches and tools can be applied in the context of variable drug response with the goal of providing more personalized clinical management of patients with IBD.

Association of the organic cation transporter OCTN genes with Crohn's disease in the Spanish population

The SLC22A4 and SLC22A5 genes within the IBD5 risk locus encode the organic cation transporters OCTN1 and OCTN2. Two variants, 1672C>T in SLC22A4 and -207G>C in SLC22A5, were shown to alter these genes' functions and were identified as genetic susceptibility factors for Crohn's disease (CD). We pursued to check both putative etiologic variants in an independent population through a case-control study with 309 Spanish CD patients and 408 ethnically matched healthy subjects. Both polymorphisms were found in partial linkage disequilibrium (D'=0.86). The separate analysis of each OCTN variant evidenced no association. However, when the simultaneous presence of mutant variants in both genes was analyzed, an effect on CD susceptibility was observed (P=0.026, odds ratio (OR) (95% confidence interval (CI))=1.59 (1.03-2.45)). The previously described predisposition conferred by the 5q31-risk haplotype increased in the absence of the etiologic 1672T and -207C alleles (P=0.0006, OR (95% CI)=10.14 (1.97-98.04)). Moreover, the risk contributed by these polymorphisms was higher in the IBD5 wild-type population (P=0.003, OR (95% CI)=2.65 (1.32-5.35)), arguing against the exclusive etiological role of the OCTN variants. The haplotype pattern inferred led to the consideration of these variants as susceptibility markers only in a defined genetic context. Our data support the interpretation of the 1672C>T SLC22A4 and -207G>C SLC22A5 polymorphisms as genetic markers of susceptibility/protection haplotypes.

Genetic variants and the risk of Crohn's disease: what does it mean for future disease management?

Genetic research in inflammatory bowel disease, especially in Crohn's disease, has made significant progress during recent years. There have been > 10 total genome scans that have been performed, and susceptibility loci on several chromosomes have been identified. Together with candidate gene studies, these scans have led to the identification of several susceptibility genes, with CARD15 being the most important. These genetic data have already provided important insights into the pathophysiology of inflammatory bowel disease and are stimulating future research. On the other hand, genotype-phenotype associations have illustrated the heterogenic nature of the disease. Although the clinical application of this knowledge is so far limited, there is significant optimism that an individual management of patients based on genetic data will be possible in the near future.

Family and twin studies in inflammatory bowel disease

Studies examining the inheritance of inflammatory bowel disease (IBD) within different family groups have been the basis for recent molecular advances in the genetics of IBD. The derived heritability in Crohn’s disease (CD) is higher than in many other complex diseases. The risk of IBD is highest in first-degree relatives of a CD proband, but first-degree relatives of a proband suffering from ulcerative colitis (UC) and more distant relatives are also at increased risk. Disease concordance rates in IBD have been examined in multiplex families and in three large European twin studies.

Do patients with inflammatory bowel disease want genetic testing?

BACKGROUND

Inflammatory bowel disease (IBD) is a complex genetic disorder characterized by nonmendelian inheritance, incomplete penetrance, and disease susceptibility but not disease certainty. Genotype and phenotype associations are described, but the level of interest of patients with IBD in genetic testing for themselves or at-risk family members remains unknown. Thus, the goal of this study was to assess the interest of patients with IBD in genetic testing and their willingness to accept the uncertainty inherent in complex genetics.

MATERIALS AND METHODS

Consecutive outpatients with IBD were recruited to complete a 57-item self-administered survey. The survey included a layperson explanation of the limits of IBD genetics. A 5-point Likert scale was used to determine willingness to undergo genetic testing to determine diagnosis, prognosis, and treatment; to help their family; and to advance medical knowledge. The IBD Questionnaire, a validated measure of the health status attitudes of patients with IBD, was used. To determine limits of patient interest in testing family members, the standard reference gamble paradigm was used. Patients were presented with situations for the genetic test with various levels of certainty in 10% decrements starting with 100%. They indicated the lowest degree of certainty that they would accept to test their family member.

RESULTS

One hundred fourteen patients (mean age 38.4 years; 48.2% women) completed the survey. Of these 114, 71.9% (82) had Crohn's disease. Among the patients who answered questions on self-willingness, 76.8% (86 of 112) would undergo testing for diagnostic confirmation, 81.3% (91 of 112) for prognostic value, 88.4% (99 of 112) for therapeutic decision making, and 85.0% (96 of 113) for advancement of medical knowledge. We found that 28.1% of patients (32 of 114) had a first-degree relative with IBD. Those patients with a first-degree relative with IBD were more willing to undergo genetic testing than those without a first-degree relative with IBD (raw score on self-willingness 4.62 vs 4.36; P=0.026). There was no significant association between patients' health status and their willingness to undergo genetic testing (IBD Questionnaire score and raw score on self-willingness; Spearman's correlation coefficient -0.06; P=0.51). We also found that 88.6% of patients (93 of 105) indicated an interest in testing family members if the test provided absolute certainty of future disease. The average lowest level of certainty these patients were willing to accept was 42.2%.

CONCLUSIONS

Despite the complexity of IBD genetics, most patients with IBD are interested in testing and willing to accept a variable degree of uncertainty about the results. An important minority of patients does not wish to be tested. Future work should better identify the reasons for these different attitudes. This information should be factored into plans for widespread clinical testing.

TNF-857 polymorphism in Israeli Jewish patients with inflammatory bowel disease

Tumour necrosis factor (TNF)-alpha is an important pro-inflammatory cytokine that has been implicated in the pathogenesis of inflammatory bowel disease (IBD). The promoter TNF-857 C-->T single nucleotide polymorphism (SNP) is functional through the binding to the transcription factor octamer transcription factor-1 (OCT-1). In order to investigate the frequency of this SNP in Israeli Jewish IBD patients, we analysed a cohort of well-characterized patients, 153 with Crohn's disease (CD) and 78 with ulcerative colitis (UC) and 188 healthy controls individually matched for age, sex and ethnicity. Forty-one per cent of the patients were of Ashkenazi and 48% were of non-Ashkenazi background. The remaining 11% were of mixed Ashkenazi-non-Ashkenazi background. Patients and controls were genotyped for the TNF-857 SNP by Taqman technology. Stratification for the CARD15 Arg702Trp, Gly908Arg and Leu1007fsinsC mutations took place in 136 CD patients. Carrier frequency of TNF-857T between CD and controls (36% vs. 40%; P = 0.556; OR: 1.18, 95% CI 0.74-1.88), or between UC and controls (41% vs. 37%; P = 0.743; OR: 0.85, 95% CI 0.45-1.62) did not differ significantly. Neither did stratifying for the presence of at least one of the common CARD15 mutations result in a significant difference between CD and controls. No associations were found between TNF-857T and CD phenotype as defined by the Vienna classification, perianal disease or extra-intestinal disease irrespective of CARD15 carrier status. In conclusion, it appears that TNF-857 SNP does not contribute to susceptibility of IBD, neither does it define the phenotype of CD in Israeli Jewish IBD patients.

Current concept on the pathogenesis of inflammatory bowel disease-crosstalk between genetic and microbial factors: Pathogenic bacteria and altered bacterial sensing or changes in mucosal integrity take “toll”

The pathogenesis of inflammatory bowel disease (IBD) is only partially understood. Various environmental and host (e.g. genetic-, epithelial-, immune and non-immune) factors are involved. It is a multifactorial polygenic disease with probable genetic heterogeneity. Some genes are associated with IBD itself, while others increase the risk of ulcerative colitis (UC) or Crohn’s disease (CD) or are associated with disease location and/or behaviour. This review addresses recent advances in the genetics of IBD. The article discusses the current information on the crosstalk between microbial and genetic factors (e.g. NOD2/CARD15, SLC22A46A5 and DLG5). The genetic data acquired in recent years help in understanding the pathogenesis of IBD and can identify a number of potential targets for therapeutic intervention. In the future, genetics may help more accurately diagnose and predict disease course in IBD.

Role of the IBD5 susceptibility locus in the inflammatory bowel diseases

The field of inflammatory bowel disease genetics plays a leading role in the genetics of complex traits. One of the first genetic loci for a complex trait to be identified by genome-wide linkage scans and confirmed by multiple studies was IBD1 for Crohn's disease. Shortly after this initial success, a second susceptibility locus, the IBD5 risk haplotype, was discovered and unequivocally replicated. In this review, we examine the genetics and potential functional implications of the IBD5 locus on disease susceptibility, prognosis, classification, and treatment. In addition, we discuss the challenges faced when the region identified by association contains multiple genes that are not easily separated by recombination-the primary tool of the human geneticist.

Is perianal Crohn's disease associated with intestinal fistulization?

BACKGROUND

When cases of Crohn's disease (CD) are described as "fistulizing," distinctions are often not drawn between perianal and intestinal fistulization. The question, therefore, remains open as to whether or not there is truly an association between perianal fistulization and intraabdominal intestinal fistulization in CD.

AIMS

We have sought to determine the association between perianal and intestinal fistulization by analyzing the cases of CD recorded in databases from six international centers.

PATIENTS

Six databases provided information on 5491 cases of CD in the United States, France, Italy, and The Netherlands. Of these cases, 1686 had isolated ileal disease and 1655 had Crohn's colitis.

METHODS

An association between perianal disease and internal fistulae was sought by calculating relative risks for the chance of internal fistulae among patients with perianal fistulae relative to those without. Statistical significance was calculated by the Mantel-Haenszel procedure, stratifying on the separate centers. All statistical tests and estimates were implemented using SAS for the PC.

RESULTS

Among the 1686 cases with isolated ileal disease, the evidence of an association between perianal disease and internal fistulization was not consistent across centers, with relative risks ranging from 0.8 to 2.2. For patients with Crohn's colitis (n = 1655), the association was much stronger and more consistent, with an estimated common relative risk of 3.4, 95% confidence interval (2.6-4.6, p < 0.0001).

CONCLUSIONS

We have found a statistically significant association between perianal CD and intestinal fistulization, much stronger and more consistent in cases of Crohn's colitis than in cases limited to the small bowel.