Progress in searching for susceptibility gene for inflammatory bowel disease by positional cloning

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.

The study of methylation and single nucleotide polymorphisms of cancer-related genes in patients with early-stage ulcerative colitis

Aim: To investigate the methylation status and single nucleotide polymorphisms (SNPs) of cancer-associated genes in ulcerative colitis (UC) patients and explore the potential mechanism for high cancer risk of UC. Methods: A total of 103 patients were enrolled in our study, which included 30 healthy subjects, 41 patients with early-stage UC, and 32 patients with colorectal cancer (CRC). Methylation status of cyclooxygenase 2 (COX2) and human RUNT-related transcription factor 3 (RUNX3) genes in colonic mucosa from 3 groups of subjects were detected by methylation-specific polymerase chain reaction (PCR). The SNPs TNF-α rs1800629 and IL-1 rs1143627 were genotyped by PCR and direct sequencing. Results: The methylation rate of RUNX3 gene within CRC group was 35.7%, which was significantly higher than the other two groups (Healthy control 5.9%, UC 15.4%, p = .040). There was no significant difference in the methylation rate of RUNX3 between early-stage UC group and healthy control group (p = .633). The methylation rate of COX2 gene, the genotypes (GG, AG) and alleles (A, G) of rs1800629, and the genotypes (CC,CT,TT) and alleles (C,T) of rs1143627 were not statistically different among three groups. Conclusion: In the early stage of UC, the methylation rate of cancer-related genes RUNX3 and COX2 and SNPs TNF-α rs1800629 and IL-1 rs1143627 were not significantly different compared with healthy subjects. The methylation rate of RUNX3 in CRC increased, while the methylation rate of COX2 and SNPs TNF-α rs1800629 and IL-1 rs1143627 did not change significantly compared with the other two groups.

新疆维吾尔族和汉族溃疡性结肠炎患者IL-23R基因多态性的初步研究

目的

初步探讨新疆维汉民族溃疡性结肠炎(ulcerative colitis, UC)患者及正常对照人群中白介素23受体(interleukin-23 receptor, IL-23R)基因中9个单核苷酸多态性(single nucleotide polymorphism, SNP)位点的基因型, 以探究IL-23R基因的UC易感位点.

方法

采用SNaPshot SNP分型技术对263个样本进行9个SNP位点基因分型, 分析上述位点基因型, 对比维汉民族、维吾尔族UC组与对照组, 汉族UC组与对照组上述位点基因型频率、等位基因频率, 探索IL-23R基因的UC易感位点及其在维汉民族间有无差异.

结果

与维吾尔族对照组相比, 维吾尔族UC组在rs11805303、rs17375018基因型上差异有统计学意义(P<0.05). 与汉族对照组相比, 汉族UC组在rs1495965、rs11805303、rs17375018基因型上差异有统计学意义(P<0.05). 维吾尔族UC组与汉族UC组在上述9个SNP位点的基因型差异无统计学意义(P>0.05).

结论

IL-23R基因的rs1495965、rs11805303、rs17375018可能是影响UC发病的易感位点, 但本研究涉及IL-23R基因9个SNP位点基因型在维汉民族间无明显差异, 考虑上述位点可能不是民族易感性位点.

Association between STAT3 gene polymorphisms and Crohn's disease susceptibility: a case-control study in a Chinese Han population

Background

Crohn’s disease (CD) is an immune-related disease with genetic predisposition. This study aimed to investigate the association of three polymorphisms in the signal transducer and activator of transcription 3 (STAT3) gene with CD risk in a Chinese population.

Methods

We conducted a hospital-based case–control study involving 232 CD patients and 272 controls. Genotyping was performed using polymerase chain reaction with sequence-specific primer method. Statistical analyses were conducted using logistic regression and genotype risk scoring.

Results

Significant differences were found between patients and controls in allele/genotype distributions of rs744166 (Pallele = 0.0008; Pgenotype = 0.003) and allele distributions of rs4796793 (P = 0.03). The risk for CD associated with the rs744166-A mutant allele decreased by 37% [95% confidence interval (CI): 0.48–0.83] under the additive model, 39% (95% CI: 0.43–0.81) under the dominant model and 57% (95% CI: 0.24–0.77) under the recessive model. Carriers of the rs4796793-G mutant allele exhibited 25% (95% CI: 0.58–0.98; P = 0.03) and 47% (95% CI: 0.30–0.95) decreased risks of developing CD under the additive and recessive models, respectively.

Conclusions

STAT3 rs744166 and rs4796793 polymorphisms may be associated with CD occurrence and used as a predictive factor of CD in Chinese Han populations.

Virtual Slides

The virtual slide(s) for this article can be found here: http://diagnosticpathology.slidepath.com/webViewer.php?snapshotId=1297687014

Role of genes, the environment and their interactions in the etiology of inflammatory bowel diseases

Few of the studied genes demonstrate association with inflammatory bowel disease (IBD). Three mutations in the nucleotide-binding oligomerization domain 2 gene have consistently shown to be independent risk factors for Crohn's disease, but none of the alleles exhibited high sensitivity or specificity for IBD. Linkage analysis implicated several loci on various chromosomes, and epistasis has been demonstrated. The etiopathogenesis of IBD remains unknown, and environmental contribution to their pathogenesis is evident from genetic studies that demonstrated incomplete monozygotic twins concordandance rate for both Crohn's and ulcerative colitis. Smoking has shown an opposite effect on disease phenotype, with an adverse effect on disease course for Crohn's disease, but a slight beneficial effect in ulcerative colitis. The contribution of infectious agents to susceptibility to IBD appears to be strong. However, the role of nutrition on the etiology and therapy of IBD is not clear. Inconsistencies in environmental risk factors could be due to gene-environment interactions, making it essential to study the role of genetics and environmental contribution to the etiopathology of IBD. Transgenic or knockout mice, such as interleukin-10(-/-), T-cell receptor alpha(-/-), Galphai(2) (-/-) and N-cadherin(-/-), develop colitis-like inflammation similar to humans. Therefore, animal models must be further studied to explore mechanistic interactions.

Carbohydrate Elimination or Adaptation Diet for Symptoms of Intestinal Discomfort in IBD: Rationales for "Gibsons' Conundrum"

Therapeutic use of carbohydrates in inflammatory bowel diseases (IBDs) is discussed from two theoretical, apparent diametrically opposite perspectives: regular ingestion of prebiotics or withdrawal of virtually all carbohydrate components. Pathogenesis of IBD is discussed connecting microbial flora, host immunity, and genetic interactions. The best studied genetic example, NOD2 in Crohn's disease, is highlighted as a model which encompasses these interactions and has been shown to depend on butyrate for normal function. The role of these opposing concepts in management of irritable bowel syndrome (IBS) is contrasted with what is known in IBD. The conclusion reached is that, while both approaches may alleviate symptoms in both IBS and IBD, there is insufficient data yet to determine whether both approaches lead to equivalent bacterial effects in mollifying the immune system. This is particularly relevant in IBD. As such, caution is urged to use long-term carbohydrate withdrawal in IBD in remission to control IBS-like symptoms.

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.

Host-bacteria interactions in the intestine: homeostasis to chronic inflammation

In the past decade it has become clear that the gut constitutes an important frontier of the body, which not only regulates the selective entry of nutrients while keeping vigilant against pathogens but also is largely responsible for shaping the immune response to educate the organism to recognize self from non-self. The very notion of self has undergone a dramatic change, with the acknowledgment that our 'selves' include a plethora of microbial species that actively participate in our body's homeostasis. The immune system continuously adapts to the microbiota in a cyclic, dynamic cross talk where intestinal epithelial cells play an important role in instructing noninflammatory responses for a steady-state control of bacterial growth, or triggering inflammatory mechanisms that can clear the gut from harmful invaders. The system is complex and robust in the sense that many players with partially overlapping roles act to keep the integrity of the intestinal mucosal barrier. Failure of these mechanisms involves genetic and environmental triggers and leads to inflammatory bowel disease. In this review, we seek to collect the state-of-the-art knowledge about how host and microbiota interact to promote gut homeostasis and provide evidences of malfunctioning of the described mechanisms in human inflammatory bowel disease.

Inflammatory bowel disease: review from the aspect of genetics

Regardless of how inflammatory bowel disease (IBD) is defined, the term "genetic susceptibility" is always included. Due to substantial progress in the characterization of susceptible genes that interact with environmental influences, a number of review articles offering the latest insights continue to be presented. To date, more than 30 novel IBD susceptible loci have been found, while several promising associations between IBD and gene variants have also been identified and replicated effectively. The present review highlights recent insights regarding linkage analysis and genome-wide association presented in studies of IBD susceptible genes, which provide additional evidence supporting their involvement in disease pathogenesis, based on linking to innate immune systems as a result of interactions with intestinal microbial flora. An improved understanding of IBD genetics will promote the identification of novel therapeutic agents, making it possible to identify environmental factors related to intestinal inflammation.

1007fs, G908R, R702W mutations and P268S, IVS8+158 polymorphisms of the CARD15 gene in Turkish inflammatory bowel disease patients and their relationship with disease-related surgery

INTRODUCTION

CARD15 gene mutations may present different frequencies in populations and sometimes surgical interventions may become a necessary therapy for inflammatory bowel disease patients. Mutations of 1007fs, G908R, R702W and polymorphisms of P268S, IVS8+158 of the CARD15 gene and their relation with disease-related surgery were investigated in Turkish inflammatory bowel disease patients in this study.

MATERIAL AND METHOD

1007fs, G908R, R702W mutations and P268S, IVS8+158 polymorphisms of CARD15 gene were analyzed in 130 inflammatory bowel disease patients (67 Crohn's disease, 63 ulcerative colitis) and 87 healthy controls. After obtaining DNA samples, genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Results were evaluated by statistical analysis and accepted as significant if P < 0.05.

RESULTS

R702W gene mutation was significantly lower in the inflammatory bowel disease group (1.5%) than the controls (4.8%) (P < 0.05). The overall allele frequency of mutations in the inflammatory bowel disease group (2.7%) was lower than in controls (6.6%) (P < 0.05). Disease-related surgery history was present in 20 Crohn's and 25 ulcerative colitis patients; familial history was present in four Crohn's and five ulcerative colitis patients. Statistically, no relationship was detected between disease-related surgeries and the investigated genetic tests.

CONCLUSION

In Turkish patients, no important relationship was detected between the investigated allele frequencies of the CARD15 gene and inflammatory bowel disease nor between disease-related surgeries and inflammatory bowel disease.

Advances in studies on relation between inflammatory bowel disease and immunity

Inflammatory bowel disease is a chronic inflammatory disease of the gastrointestinal tract. Its main clinical manifestations are abdominal pain and diarrhea. Its etiology is complicated. Immune system is very important. Following factors, such as intestinal environment, immune cells, human leukocyte antigens, antibodies, anti- laminaribioside antibody, anti-chitobioside antibody IgA, cytokines, cell adhesion molecules, NO and NF-κB, play a key role in the pathogenesis of inflammatory bowel disease. Inflammatory bowel disease is related to all these factors. This paper reviews the possible role of these immune factors in the pathogenesis of inflammatory bowel disease.

Effects of surgery on peripheral N-terminal propeptide of type III procollagen in patients with Crohn's disease

AIM

This study investigates the effects of surgery on collagen turnover in patients affected by Crohn's disease (CD).

METHODS

Fifteen patients affected by active CD, assessed according to the Crohn's disease activity index, and confirmed by histology, with different pharmacological treatments, were enrolled in the study. N-Terminal propeptide of type III collagen was assessed on peripheral blood before and 6 months after surgery, as an index of collagen turnover. A control group of 15 healthy age- and sex-matched subjects was also studied.

RESULTS

In CD patients peripheral N-terminal propeptide of type III collagen serum levels were significantly higher than in controls before surgery (5.0 +/- 1.8 vs 2.7 +/- 0.7 microg/l, respectively; p = 0.0001). Six months after these values were significantly reduced (from 5.0 +/- 1.8 to 3.1 +/- 0.8 microg/l; p = 0.003). Independently on the pretreatment regimen and the duration of the disease, an improvement in the patients' symptoms was observed.

CONCLUSIONS

The surgical resection of the affected intestinal segment in CD patients seems to be able to break down the collagen synthesis processes. Peripheral N-terminal propeptide of type III collagen could be seen as an additive marker to clinical and endoscopic observations after surgery.

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.

Multidrug resistance 1 gene polymorphism and susceptibility to inflammatory bowel disease

BACKGROUND

Several studies have evaluated the role of the multidrug resistance 1 gene (MDR1) polymorphism, which encodes the membrane-bound efflux transporter P-glycoprotein 170, in determining susceptibility to and disease behavior in inflammatory bowel disease (IBD), but with conflicting results.

METHODS

A total of 211 patients with Crohn's disease (CD), 97 patients with ulcerative colitis (UC), and 212 control subjects were investigated for the presence of MDR1 G2677T/A and C3435T polymorphisms. Genotype frequencies of CD and UC patients were compared to those observed in a control population. Genotype-phenotype correlations with major clinical features were also established and estimated risks (odds ratio [OR] with 95% confidence interval [CI]) for the mutations were calculated by a logistic regression analysis and multiple correspondent analysis.

RESULTS

No significant difference was observed for genotype frequencies for both MDR1 G2677T/A and C3435T polymorphisms on overall disease susceptibility for either CD or UC patients compared with control subjects. A significant association was found between the MDR1 C3435T polymorphism and patients with ileo-colonic CD (OR = 3.34; 95% CI: 1.34-8.27). Interestingly, a negative association was found between MDR1 C3435T polymorphism in patients with a positive family history for IBD (OR = 0.44; 95% CI: 0.20-0.95) and articular manifestations (OR = 0.29; 95% CI: 0.13-0.68). Both susceptible and protective effects were identified. No significant association between G2677T/A polymorphism and any specific subphenotypes was found, nor was there any association with subphenotypic categories of UC and both single nucleotide polymorphisms.

CONCLUSIONS

The results of our study suggest that MDR1 gene polymorphism could have a role in determining susceptibility to IBD. The variability of this possible effect in the several studies reported so far may be the indirect expression of the complex role played by the MDR1 gene and its product, P-glycoprotein 170, in the regulation of host-bacteria interactions and in the pathogenesis of IBD.

Recent advances in basic and clinical aspects of inflammatory bowel disease: Which steps in the mucosal inflammation should we block for the treatment of inflammatory bowel disease?

There are four steps in the interaction between intestinal microbes and mucosal inflammation in genetically predisposed individuals from the viewpoints of basic and clinical aspects of inflammatory bowel disease (IBD). The first step is an interaction between intestinal microbes or their components and intestinal epithelial cells via receptors, the second step an interaction between macrophages and dendritic cells and mucosal lymphocytes, the third step an interaction between lymphocytes and vascular endothelial cells, and the fourth step an interaction between lymphocytes and granulocytes producing proinflammatory cytokines or free radicals and mucosal damage and repair. Recent therapeutic approaches for IBD aim to block these four steps in the intestinal inflammation of patients with IBD.

Association of NOD2/CARD15 mutations on Crohn's disease phenotype in an Italian population

AIMS

To confirm the prevalence of NOD2/CARD15 mutations in Italian inflammatory bowel disease patients and to define the role of the different mutations on Crohn's disease phenotype.

PATIENTS AND METHODS

A total of 177 patients with Crohn's disease and 92 patients with ulcerative colitis and 164 control participants were investigated for the presence of Arg702Trp, Gly908Arg and Leu1007fsinsC NOD2/CARD15 mutations. Allele frequencies in Crohn's disease and ulcerative colitis patients were compared with those observed in the control population. Genotype-phenotype correlations with the major clinical features were also established and estimated risks (odds ratio with 95% confidence interval) for the mutations were calculated by logistic regression and multiple correspondent analysis.

RESULTS

Gly908Arg and Leu1007fsinsC mutations were significantly more frequent in Crohn's disease patients compared with healthy controls (P<0.01 and <0.003 respectively). Indeed, using a logistic regression model adding terms for age (differently distributed between cases and controls) and sex, a significantly increased risk of having Crohn's disease compared with healthy controls was found for all NOD2 mutations: Leu1007fsinsC (odds ratio=7.35; 95% confidence interval: 1.73-31.3), Gly908Arg (odds ratio=5.70; 95% confidence interval: 1.37-23.7) and Arg702Trp (odds ratio=2.45; 95% confidence interval: 1.10-5.47). As far as the genotype-phenotype correlations are concerned, by multivariate conditional logistic regression methods, we found a significant association between Gly908Arg mutations and familial history of inflammatory bowel disease, between Leu1007fsinsC mutations and appendectomy and between Arg702Trp mutations and fibrostenotic phenotype of Crohn's disease. A nonsignificant association between Arg702Trp variants and ileal disease was also found (odds ratio=8, 95% confidence interval: 0.99-64.9).

CONCLUSIONS

The results of the study confirm a significant association of CARD15 gene mutations in our Italian Crohn's disease population and the impact of different NOD2/CARD15 mutations on specific disease phenotypes.

Hypertrophic cardiomyopathy in a patient with Crohn's disease: A case report

Cardiac manifestations of Crohn's disease are rare; the most common is pericarditis. In the present report we briefly describe a 56-year-old man with Crohn's disease who presented to the emergency department due to paroxysmal atrial flutter. A transthoracic echocardiographic study revealed asymmetric left ventricular hypertrophy without outflow pressure gradient. Reviewing the literature, hypertrophic cardiomyopathy has not been previously described in patients with Crohn's disease.

Loss of fragile histidine triad protein expression in inflammatory bowel disease

AIM: To investigate the expression of fragile histidine triad (FHIT) protein in 64 patients with ulcerative colitis (UC) and Crohn’s disease (CD), and its relation with clinicopathological data.

METHODS: Rabbit-anti-FHIT antibody was used to detect FHIT protein expression in 64 formalin-fixed, paraffin-embedded tissue specimens of inflammatory bowel disease (IBD) by citrate-microwave-streptavidin (SP)-HRP immunohistochemical method.

RESULTS: The positive FHIT protein expression was 22.79% ± 16.16%, 42.14% ± 16.82% in active and remittent phases of UC, 36.07% ± 19.23% in CD, and 57.05% ± 8.86% in normal colon mucosa. Statistically significant differences in FHIT protein expression were observed between the active and remittent phases of UC, between the active phase of UC and normal colon mucosa, as well as between the remittent phase of UC and normal colon mucosa, and between CD and normal colon mucosa.

CONCLUSION: Our results show that FHIT protein expression is completely absent or reduced in IBD, suggesting that the FHIT gene might be associated with the oncogenesis and progression of IBD, an early event from inflammatory conditions to carcinoma in IBD.

Is the incidence and prevalence of inflammatory bowel diseases increasing in Eastern Europe?

Limited data are available on the frequency of inflammatory bowel diseases in East European countries. A recent study from Hungary reported an increasing incidence rate for ulcerative colitis (from 1.6 to 11.0) and for Crohn's disease (from 0.4 to 4.7) from 1977 to 2001. A similar trend was seen in Croatia. In contrast, other countries (for example, Czech Republic, Poland, Romania, Slovakia, and Baltic countries) reported low incidence and prevalence rates. This review will discuss the available data on the epidemiology of inflammatory bowel diseases in Eastern Europe, as well as consider the possible factors responsible for the differences seen between countries and epidemiological trends.

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.

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DLG5 variants do not influence susceptibility to inflammatory bowel disease in the Scottish population

INTRODUCTION

Recent data have suggested that specific haplotypic variants of the DLG5 gene on chromosome 10q23 may be associated with susceptibility to inflammatory bowel disease (IBD) in Germany. Haplotype D, notably characterised by the presence of a G-->A substitution at nucleotide 113, was associated with susceptibility to Crohn's disease (CD) whereas an extended haplotype A conferred protection.

AIMS

Association of DLG5 haplotypic variants with disease susceptibility, genotype-phenotype relationships, and epistasis with CARD15 was investigated in the Scottish population.

PATIENTS AND METHODS

A total of 374 CD, 305 ulcerative colitis (UC), and 294 healthy controls (HC) were studied. Genotyping for the variants rs1248696 (113A, representing haplotype D) and the single nucleotide polymorphism tag rs2289311 (representing haplotype A) were typed using the Taqman system.

RESULTS

On analysis of the DLG5 variant 113A, there were no associations with IBD when allelic frequency (11.4% IBD v 13.2% HC; p = 0.30) and carrier frequency (19.2% IBD v 24.6% HC; p = 0.069) were analysed. No associations were observed between 113A variant allelic frequency (p = 0.37), carrier frequency (p = 0.057), and CD. In fact, 113A heterozygosity rates were lower in CD (16%) and IBD (16.9%) than in HC (23%) (p = 0.029 and p = 0.033, respectively). No associations between DLG5 and UC were observed. Haplotype A was not protective and there was no evidence of epistasis between DLG5 and CARD15.

CONCLUSIONS

The present data contrast strongly with previous data from Germany. DLG5 113A is not associated with disease susceptibility and haplotype A does not confer resistance. Further work is required to evaluate the significance of DLG5 in other populations from geographically diverse regions.

The G2964A polymorphism of the STAT6 gene in inflammatory bowel disease

BACKGROUND AND AIMS

Linkage of inflammatory bowel diseases to chromosome 12p13.2-q24.1 (IBD2) has been confirmed in several genome wide screens. The STAT6 gene is located within this chromosomal region. The transcription factor STAT6 is involved in the regulation of the TH1/TH2 immune response. Increased production of TH1 cytokines is crucial in the pathogenesis of Crohn's disease.

PATIENTS AND METHODS

Therefore, we genotyped a single nucleotide polymorphism in the 3' untranslated region of the STAT6 gene (G2964A) in 243 patients with Crohn's disease, 100 patients with ulcerative colitis and 548 healthy controls.

RESULTS

In comparison to controls, the G allele and the GG genotype frequencies were significantly increased only in Crohn's disease patients without a variation in the CARD15 gene (p<0.03 and p<0.02, respectively).

CONCLUSIONS

Alterations in the STAT6 pathway may play a crucial role in the pathogenesis of distinct subgroups of patients with Crohn's disease.

Variants of CARD15 are associated with an aggressive clinical course of Crohn's disease--an IG-IBD study

BACKGROUND

Three major variants of the CARD15 gene confer susceptibility to Crohn's disease (CD). Whether or not these variants correlate with specific clinical features of the disease is under evaluation.

AIM

We investigated the possible association of CARD15 variants with specific clinical characteristics, including the occurrence of anti-Saccharomyces cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies (ANCA), in a large cohort of inflammatory bowel disease (IBD) patients and their unaffected relatives.

METHODS

Three hundred and sixteen CD patients (156 with positive family history), 408 ulcerative colitis (UC) patients (206 with positive family history), 588 unaffected relatives, and 205 unrelated healthy controls (HC) were studied. Single nucleotide polymorphisms (SNPs) R702W, G908R, and L1007finsC of the CARD15 gene were investigated and correlated to age at diagnosis, gender, family history, localization, extraintestinal manifestations, previous resective surgery, stenosing/fistulizing pattern, ANCA, and ASCA.

RESULTS

Compared to HC, the frequencies of all three variants in CD were significantly increased: 8.7% versus 4.1% for R702W (p < 0.006), 7.3% versus 2.7% for G908R (p < 0.002), 9.3% versus 0.7% for L1007finsC (p < 0.00001). At least one risk allele was found in 38.2% (p < 0.0001, compared to HC), 13.7% (NS), and 15.1% of CD, UC, and HC, respectively. The L1007finsC risk allele was also significantly increased in unaffected relatives of familial (9.5%; p < 0.00001), and sporadic CD (9%; p < 0.00001), compared to HC (0.7%). Sixteen healthy relatives, carriers of two risk alleles, were asymptomatic after 5-8 yr of follow-up. CD carriers of at least one variant were younger (p= 0.03), more likely to have ileal localization (p= 0.0001), stenosing pattern (p= 0.01), previous resective surgery (p= 0.0001), and presence of ASCA (p= 0.0001). No difference in SNPs frequency between familial and sporadic cases of CD was found.

CONCLUSION

In our population, both familial and sporadic CD patients carrying at least one major variant of CARD15 had an aggressive clinical course.

Elevated serum procollagen type III peptide in splanchnic and peripheral circulation of patients with inflammatory bowel disease submitted to surgery

BACKGROUND

In the hypothesis that the increased collagen metabolism in the intestinal wall of patients affected by inflammatory bowel disease (IBD) is reflected in the systemic circulation, we aimed the study to evaluate serum level of procollagen III peptide (PIIIP) in peripheral and splanchnic circulation by a commercial radioimmunoassay of patients with different histories of disease.

METHODS

Twenty-seven patients, 17 with Crohn and 10 with ulcerative colitis submitted to surgery were studied. Blood samples were obtained before surgery from a peripheral vein and during surgery from the mesenteric vein draining the affected intestinal segment. Fifteen healthy age and sex matched subjects were studied to determine normal range for peripheral PIIIP.

RESULTS

In IBD patients peripheral PIIIP level was significantly higher if compared with controls (5.0 +/- 1.9 vs 2.7 +/- 0.7 microg/l; p = 0.0001); splanchnic PIIIP level was 5.5 +/- 2.6 microg/l showing a positive gradient between splanchnic and peripheral concentrations of PIIIP. No significant differences between groups nor correlations with patients' age and duration of disease were found.

CONCLUSIONS

We provide evidence that the increased local collagen metabolism in active IBD is reflected also in the systemic circulation irrespective of the history of the disease, suggesting that PIIIP should be considered more appropiately as a marker of the activity phases of IBD.

Clinical relevance of advances in genetics and pharmacogenetics of IBD

Crohn's disease and ulcerative colitis result from an inappropriate response of the mucosal immune system to the normal enteric flora in a genetically susceptible individual. During the past decade, exciting progress has been made in our understanding of the contribution of genetics to inflammatory bowel disease susceptibility and phenotype. This article reviews recent advances in the genetics of inflammatory bowel disease and explores how they might impact on clinical practice. Current knowledge of the genetic basis for disease susceptibility, phenotype, and response to therapy is explored and the factors currently limiting the translation of this knowledge to clinical practice is discussed.

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