Crohn disease: frequency and nature of CARD15 mutations in Ashkenazi and Sephardi/Oriental Jewish families

Association of polymorphous light eruption with NOD-2 and TLR-5 gene polymorphisms

BACKGROUND

Polymorphous light eruption (PLE) is a common, immunologically mediated, photosensitive skin disease. After ultraviolet-B (UV-B) irradiation, patients with PLE show reduced Langerhans cell (LC) depletion in the epidermis, which results in a non-suppressive microenvironment in the skin. Interestingly, severe acute graft-versus-host-disease (aGvHD) occurred in stem cell transplanted patients that showed no or incomplete depletion of LCs after UVB-irradiation. Genetic variation in nucleotide-binding oligomerization domain 2 (NOD-2) and toll-like receptor 5 (TLR-5) genes also confers susceptibility to aGvHD.

OBJECTIVES

We hypothesized that PLE is associated with genetic variation in the NOD-2 and TLR-5 genes.

METHODS

We investigated single nucleotid polymorphisms (SNPs) of NOD-2 (R702W, G908R, 3020Cins) and TLR-5 (A592S, P616L, N392STOP) in skin biopsies of PLE-patients (n=143) and in healthy controls (n=104) using restriction fragment-length polymorphism analysis.

RESULTS

The frequency of NOD-2 alleles with the SNP R702W was significantly higher in PLE than in controls (31.8% vs 6.3%; p<0.0001), and homozygous carriers of this mutation were more common in PLE (27.9% vs 0%; p<0.0001). For SNP 3020Cins, the allele frequency (7.3% vs 0.7%; p=0.0025) and the number of heterozygotes (14.7% vs 1.3%; p=0.0019) were higher in PLE. The frequency of alleles with the N392STOP SNP of the TLR5 gene, which is associated with a truncated, non-functional receptor, was significantly higher in PLE (21% vs 5%; 7% vs 1% homozygotes, 28% vs 8% heterozygotes; p<0.0001). The other SNPs did not differ significantly.

CONCLUSIONS

This study yielded a high frequency of functional SNPs in the NOD-2 and TLR-5 genes in PLE. The same SNPs are associated with aGvHD and there are similarities in the reaction of LCs after UVB-irradiation between aGvHD and PLE. This leads to the hypothesis that PLE-patients may be more susceptible to developing GvHD after stem-cell transplantation, an assumption that needs to be investigated further.

Valosin-containing protein-regulated endoplasmic reticulum stress causes NOD2-dependent inflammatory responses

NOD2 polymorphisms may affect sensing of the bacterial muramyl dipeptide (MDP) and trigger perturbed inflammatory responses. Genetic screening of a patient with immunodeficiency and enteropathy revealed a rare homozygous missense mutation in the first CARD domain of NOD2 (ENST00000300589; c.160G > A, p.E54K). Biochemical assays confirmed impaired NOD2-dependent signaling and proinflammatory cytokine production in patient’s cells and heterologous cellular models with overexpression of the NOD2 mutant. Immunoprecipitation-coupled mass spectrometry unveiled the ATPase valosin-containing protein (VCP) as novel interaction partner of wildtype NOD2, while the binding to the NOD2 variant p.E54K was abrogated. Knockdown of VCP in coloncarcinoma cells led to impaired NF-κB activity and IL8 expression upon MDP stimulation. In contrast, tunicamycin-induced ER stress resulted in increased IL8, CXCL1, and CXCL2 production in cells with knockdown of VCP, while enhanced expression of these proinflammatory molecules was abolished upon knockout of NOD2. Taken together, these data suggest that VCP-mediated inflammatory responses upon ER stress are NOD2-dependent.

Crohn's Disease Susceptibility and Onset Are Strongly Related to Three NOD2 Gene Haplotypes

The genetic background and the determinants influencing the disease form, course, and onset of inflammatory bowel disease (IBD) remain unresolved. We aimed to determine the NOD2 gene haplotypes and their relationship with IBD occurrence, clinical presentation, and onset, analyzing a cohort of 578 patients with IBD, including children, and 888 controls. Imaging or endoscopy with a histopathological confirmation was used to diagnose IBD. Genotyping was performed to assess the differences in genotypic and allelic frequencies. Linkage disequilibrium was analyzed, and associations between haplotypes and clinical data were evaluated. We emphasized the prevalence of risk alleles in all analyzed loci in patients with Crohn disease (CD). Interestingly, c.2722G>C and c.3019_3020insC alleles were also overrepresented in ulcerative colitis (UC). T-C-G-C-insC, T-C-G-T-insC, and T-T-G-T-wt haplotypes were correlated with the late-onset form of CD (OR = 23.01, 5.09, and 17.71, respectively), while T-T-G-T-wt and C-C-G-T-wt were prevalent only in CD children (OR = 29.36, and 12.93, respectively; p-value = 0.001). In conclusion, the presence of c.3019_3020insC along with c.802C>T occurred as the most fundamental contributing diplotype in late-onset CD form, while in CD children, the mutual allele in all predisposing haplotypes was the c.2798 + 158T. Identifying the unique, high-impact haplotypes supports further studies of the NOD2 gene, including haplotypic backgrounds.

NOD2/CARD15 polymorphisms (P268S, IVS8+158, G908R, L1007fs, R702W) among Kuwaiti patients with Crohn's disease: A case-control study

BACKGROUND

Nucleotide-binding oligomerization domain-containing two (NOD2/CARD15) gene polymorphisms are implicated in the pathogenesis of Crohn's disease (CD).

AIM

To describe the allelic frequency of NOD2/CARD15 gene variants among Kuwaiti patients with CD and investigate potential genotype/phenotype associations.

METHODS

Adult Kuwaiti citizens with an established diagnosis of CD and healthy controls were enrolled from October 2018 to May 2020. Three common NOD2/CARD15 polymorphisms (R702W, G908R, and L1007fs) and P268S and IVS8⁺¹⁵⁸ polymorphisms were screened by polymerase chain reaction/restriction analysis length polymorphism (PCR/RFLP).

RESULTS

Ninety adult Kuwaiti patients with CD and 210 healthy subjects (as controls) were recruited. P268S, IVS8⁺¹⁵⁸, G908R, and R702W minor alleles were identified in 38.9%, 21.1%, 12.2%, and 4.4% of CD patients, respectively. NOD2/CARD15 polymorphisms coexisted in 35 healthy controls (16.7%) and 21 CD patients (23.3%). Individuals with either a single or multiple polymorphism were approximately two times more likely to have CD than those with no polymorphism. Patients with multiple polymorphisms had significantly more stricturing and penetrating disease.

CONCLUSION

NOD2/CARD15 gene polymorphisms were significantly associated with an increased risk of disease and aggressive phenotypes among the Kuwaiti CD population.

Genetic Landscape of Rare Autoinflammatory Disease Variants in Qatar and Middle Eastern Populations Through the Integration of Whole-Genome and Exome Datasets

Rare monogenic autoinflammatory diseases are a group of recurrent inflammatory genetic disorders caused due to genetic variants in over 37 genes. While a number of these disorders have been identified and reported in Middle Eastern populations, the carrier frequency of these genetic variants in the Middle Eastern population is not known. The availability of whole-genome and exome datasets of over 1,000 individuals from Qatar persuaded us to explore the genetic epidemiology of rare autoinflammatory genetic variants. We have systematically analyzed genetic variants in genome-scale datasets from Qatar with a compendium of variants associated with autoinflammatory diseases. The variants were systematically reclassified according to the American College of Medical Genetics and Genomics guidelines for interpretation of variant pathogenicity. Our analysis identified seven pathogenic and likely pathogenic variants with significant differences in their allele frequencies compared to the global population. The cumulative carrier frequency of these variants was found to be 2.58%. Furthermore, our analysis revealed that five genes, implicated in rare autoinflammatory diseases, were under natural selection. To the best of our knowledge, this is the first and most comprehensive study on the population-scale analysis and genetic epidemiology of genetic variants that cause rare autoinflammatory disease in Middle Eastern populations.

Short article: Crohn's disease and pemphigus: is there an association?: a population-based study

BACKGROUND

Although the coexistence of Crohn's disease (CD) and pemphigus has been reported in several individuals, the association between the two conditions was not investigated systematically in the past. A recent association between pemphigus and ulcerative colitis has been reported. The study aims to estimate the association between pemphigus and CD using a large-scale real-life computerized database.

PATIENTS AND METHODS

A cross-sectional study was carried out comparing pemphigus patients with age-matched, sex-matched, and ethnicity-matched control participants in terms of the prevalence of CD. χ-Test and t-test were used for univariate analysis and a logistic regression model was used for multivariate analysis. The study was carried out utilizing the computerized database of Clalit Health Services ensuring 4.5 million patients.

RESULTS

A total of 1985 pemphigus patients and 9874 controls were included in the study. The prevalence of CD was comparable in patients with pemphigus and controls [0.4 vs. 0.3%, respectively; odds ratio (OR): 1.2; 95% confidence interval (CI): 0.5-2.5; P=0.688]. In an age-stratified analysis, a significant association was observed between pemphigus and CD in patients younger than 40 years (2.1 vs. 0.4%, respectively; OR: 5.1; 95% CI: 1.0-25.7; P=0.027). In a multivariate analysis adjusting for potential confounding factors, no independent association between the two conditions was found (OR: 0.9; 95% CI: 0.4-2.0; P=0.828). Study findings were robust to sensitivity analysis that included patients under pemphigus-specific treatments.

CONCLUSION

Unlike ulcerative colitis, CD was not associated with pemphigus. Further research is warranted to understand the pathophysiology of these observations better.

Common NOD2/CARD15 and TLR4 Polymorphisms Are Associated with Crohn's Disease Phenotypes in Southeastern Brazilians

AIM

To investigate whether variants in NOD2/CARD15 and TLR4 are associated with CD and ulcerative colitis (UC) in a genetically admixed population of Rio de Janeiro, where IBD has continued to rise.

METHODS

We recruited 67 consecutive patients with CD, 61 patients with UC, and 86 healthy and ethnically matched individuals as controls. DNA was extracted from buccal brush samples and genotyped by PCR with restriction enzymes for G908R and L1007finsC NOD2/CARD15 single-nucleotide polymorphisms (SNPs) and for T399I and D299G TLR4 SNPs. Clinical data were registered for subsequent analysis with multivariate models.

RESULTS

NOD2/CARD15 G908R and L1007finsC SNPs were found in one and three patients, respectively, with CD. NOD2/CARD15 G908R and L1007finsC SNPs were not found in any patients with UC, but were found in three and three controls, respectively. With regard to the TLR4 gene, no significant difference was detected among the groups. Overall, none of the SNPs investigated determined a differential risk for a specific diagnosis. Genotype-phenotype associations were found in only CD, where L1007finsC was associated with colonic localization; however, TLR4 T399I SNP was associated with male gender, and D299G SNP was associated with colonic involvement, chronic corticosteroid use, and the need for anti-TNF-alpha therapy.

CONCLUSION

Variants of NOD2/CARD15 and TLR4 do not confer susceptibility to IBD, but appear to determine CD phenotypes in this southeastern Brazilian population.

Dysfunctional Crohn's Disease-Associated NOD2 Polymorphisms Cannot be Reliably Predicted on the Basis of RIPK2 Binding or Membrane Association

Polymorphisms in NOD2 represent the single greatest genetic risk factor for the development of Crohn’s disease. Three different non-synonomous NOD2 polymorphisms – R702W, G908R, and L1007fsincC – account for roughly 80% of all NOD2-associated cases of Crohn’s disease and are reported to result in a loss of receptor function in response to muramyl dipeptide (MDP) stimulation. Loss of NOD2 signaling can result from a failure to detect ligand; alterations in cellular localization; and changes in protein interactions, such as an inability to interact with the downstream adaptor protein RIPK2. Using an overexpression system, we analyzed ~50 NOD2 polymorphisms reportedly connected to Crohn’s disease to determine if they also displayed loss of function and if this could be related to alterations in protein localization and/or association with RIPK2. Just under half the polymorphisms displayed a significant reduction in signaling capacity following ligand stimulation, with nine of them showing near complete ablation. Only two polymorphisms, R38M and R138Q, lost the ability to interact with RIPK2. However, both these polymorphisms still associated with cellular membranes. In contrast, L248R, W355stop, L550V, N825K, L1007fsinC, L1007P, and R1019stop still bound RIPK2, but showed impaired membrane association and were unable to signal in response to MDP. This highlights the complex contributions of NOD2 polymorphisms to Crohn’s disease and reiterates the importance of both RIPK2 binding and membrane association in NOD2 signaling. Simply ascertaining whether or not NOD2 polymorphisms bind RIPK2 or associate with cellular membranes is not sufficient for determining their signaling competency.

The NOD2 Single Nucleotide Polymorphism rs72796353 (IVS4+10 A>C) Is a Predictor for Perianal Fistulas in Patients with Crohn's Disease in the Absence of Other NOD2 Mutations

BACKGROUND

A previous study suggested an association of the single nucleotide polymorphism (SNP) rs72796353 (IVS4+10 A>C) in the NOD2 gene with susceptibility to Crohn's disease (CD). However, this finding has not been confirmed. Given that NOD2 variants still represent the most important predictors for CD susceptibility and phenotype, we evaluated the association of rs72796353 with inflammatory bowel disease (IBD) susceptibility and the IBD phenotype.

METHODOLOGY

Genomic DNA from 2256 Caucasians, including 1073 CD patients, 464 patients with ulcerative colitis (UC), and 719 healthy controls, was genotyped for the NOD2 SNP rs72796353 and the three main CD-associated NOD2 mutations rs2066844, rs2066845, and rs2066847. Subsequently, IBD association and genotype-phenotype analyses were conducted.

RESULTS

In contrast to the strong associations of the NOD2 SNPs rs2066844 (p=3.51 x 10(-3)), rs2066845 (p=1.54 x 10(-2)), and rs2066847 (p=1.61 x 10(-20)) with CD susceptibility, no significant association of rs72796353 with CD or UC susceptibility was found. However, in CD patients without the three main CD-associated NOD2 mutations, rs72796353 was significantly associated with the development of perianal fistulas (p=2.78 x 10(-7), OR 5.27, [95% CI 2.75-10.12] vs. NOD2 wild-type carriers).

CONCLUSION/SIGNIFICANCE

Currently, this study represents the largest genotype-phenotype analysis of the impact of the NOD2 variant rs72796353 on the disease phenotype in IBD. Our data demonstrate that in CD patients the IVS4+10 A>C variant is strongly associated with the development of perianal fistulas. This association is particularly pronounced in patients who are not carriers of the three main CD-associated NOD2 mutations, suggesting rs72796353 as additional genetic marker for the CD disease behaviour.

Interaction between NOD2 and CARD9 involves the NOD2 NACHT and the linker region between the NOD2 CARDs and NACHT domain

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We have studied the interaction between NOD2 and CARD9.

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The NACHT domain and CARD–NACHT linker of NOD2 are crucial for the interaction.

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The CARD domains of NOD2 and CARD9 do not directly interact.

NOD2 activation by muramyl dipeptide causes a proinflammatory immune response in which the adaptor protein CARD9 works synergistically with NOD2 to drive p38 and c-Jun N-terminal kinase (JNK) signalling. To date the nature of the interaction between NOD2 and CARD9 remains undetermined. Here we show that this interaction is not mediated by the CARDs of NOD2 and CARD9 as previously suggested, but that NOD2 possesses two interaction sites for CARD9; one in the CARD–NACHT linker and one in the NACHT itself.

NOD2 physically interacts with CARD9 by anti tag coimmunoprecipitation (View interaction)

Oral manifestations of systemic autoimmune and inflammatory diseases: diagnosis and clinical management

CONTEXT

Systemic autoimmune and inflammatory diseases often manifest oral lesions in their earliest stages, and early diagnosis, which may be spurred by a dental examination, is key for improved outcomes. After systemic diagnosis, oral lesions benefit from specialized care by dentists in collaboration with the medical team. This review aims to educate dental clinicians about the most relevant systemic autoimmune and inflammatory conditions with accompanying oral lesions, their implications for health, and management strategies supported by the biomedical literature and clinical experience. Ulcerative conditions including Behcet and Crohn diseases are discussed, along with rheumatic conditions including Sjögren syndrome, lupus erythematosus, and rheumatoid arthritis.

EVIDENCE ACQUISITION

Evidence was accumulated through PubMed searches using pertinent keywords for each subsection. References were reviewed and original publications examined to verify the accuracy of the information. We focused on evidence included in current reviews and randomized trials. Recommendations were supported by multiple studies and consensus expert opinion.

EVIDENCE SYNTHESIS

Disease phenotypes described and clinical recommendations were synthesized from best-quality evidence available for each disease. Efforts were made to describe evidence selection within each disease section.

CONCLUSIONS

Dentists play an important role in the early detection and multidisciplinary medical management of complex autoimmune diseases. It is important to recognize prevalent medical and dental issues and special needs of patients with autoimmune conditions. The management of many inflammatory conditions is similar, and often begins with the use of topical steroids, analgesics, and antimicrobial treatments, in addition to careful attention to oral hygiene and appropriate fluoride usage. In this brief review, we aim to discuss the presentation/prevalence, diagnosis, and treatment of oral manifestations encountered in autoimmune, autoinflammatory and systemic chronic inflammatory diseases. Systemic autoimmune conditions are estimated to affect 5% to 8% of Americans.(1) Oral manifestations are encountered with high frequency, and are often the first clinical signs or symptoms of the general disease. Optimal management of complex autoimmune diseases requires a multidisciplinary medical team including dentists to care for lesions of the oral cavity. The dental practitioner may be asked to play a primary role in the diagnosis of such conditions and to participate with other health professionals working together to achieve effective clinical management. To aid in this process, we discuss in this article the current general knowledge of systemic autoimmune conditions that present with prevalent oral manifestations. The focus is on the diagnosis and management of the oral component of each disease. Importantly, whereas the etiology and pathogenesis and systemic clinical presentation may vary, presentation in the oral cavity is often similar and many conditions involve oral ulcerations. For this reason, we discuss the differential diagnosis and management of the most common oral ulcerations in a general section and subsequently address individual conditions that present with oral ulcerations. Similarly, treatment of various autoimmune/inflammatory oral conditions is often common and involves modulation or suppression of the immune response locally and/or systemically and will be therefore addressed in a common section as well as individually for each disease when unique treatment regimens are recommended. We present here our general treatment recommendations based on clinical experience and literature review; however, it is critical that good clinical judgment and specifics of an individual case should determine the appropriate dental/oral medicine intervention for a specific patient.

Extended haplotype association study in Crohn’s disease identifies a novel, Ashkenazi Jewish-specific missense mutation in the NF-κB pathway gene, HEATR3. Genes Immun. 2013;14:310-316. [PMID: 23615072 PMCID: PMC3785105 DOI: 10.1038/gene.2013.19]

The Ashkenazi Jewish population has a several-fold higher prevalence of Crohn’s disease compared to non-Jewish European ancestry populations and has a unique genetic history. Haplotype association is critical to Crohn’s disease etiology in this population, most notably at NOD2, in which three causal, uncommon, and conditionally independent NOD2 variants reside on a shared background haplotype. We present an analysis of extended haplotypes which showed significantly greater association to Crohn’s disease in the Ashkenazi Jewish population compared to a non-Jewish population (145 haplotypes and no haplotypes with P-value < 10⁻³, respectively). Two haplotype regions, one each on chromosomes 16 and 21, conferred increased disease risk within established Crohn’s disease loci. We performed exome sequencing of 55 Ashkenazi Jewish individuals and follow-up genotyping focused on variants in these two regions. We observed Ashkenazi Jewish-specific nominal association at R755C in TRPM2 on chromosome 21. Within the chromosome 16 region, R642S of HEATR3 and rs9922362 of BRD7 showed genome-wide significance. Expression studies of HEATR3 demonstrated a positive role in NOD2-mediated NF-κB signaling. The BRD7 signal showed conditional dependence with only the downstream rare Crohn’s disease-causal variants in NOD2, but not with the background haplotype; this elaborates NOD2 as a key illustration of synthetic association.

Correlation of R702W, G908R and L1007fs polymorphisms of the NOD2/CARD15 gene with susceptibility to inflammatory bowel disease in Zhuang population in Guangxi, China

AIM: To investigate the relationship between R702W, G908R and L1007fs polymorphisms of the NOD2/CARD15 gene and susceptibility to inflammatory bowel disease (IBD) in a Zhuang population in Guangxi, China.

METHODS: Intestinal tissue samples of 70 Zhuang and 76 Han unrelated IBD patients and 80 Zhuang and 84 Han unrelated healthy people were collected in Guangxi from February 2007 to October 2010. Genomic DNA was prepared from these intestinal samples and used to genotype the R702W, G908R and L1007fs polymorphisms of the NOD2/CARD15 gene by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS: None of the patients with IBD and healthy controls had heterozygous or homozygous SNP variants. The distributions of genotype and allele frequencies were not significantly different between the IBD group and healthy control group. No significant differences were noted in the NOD2/CARD15 gene R702W, G908R and L1007fs polymorphisms among patients with Crohn's disease, ulcerative colitis and control subjects in Zhuang and Han populations in Guangxi (all P > 0.05). Gene mutation genotypes of the NOD2/CARD15 gene R702W, G908R and L1007fs polymorphisms were not found in these populations.

CONCLUSION: R702W, G908R and L1007fs polymorphisms of the NOD2/CARD15 gene are not associated with susceptibility to IBD in the Zhuang population in Guangxi.

CARD15/NOD2, CD14 and toll-like 4 receptor gene polymorphisms in Saudi patients with Crohn's Disease

Crohn’s disease (CD) is a multifactorial disease with a genetic component and an observed association with genes related to the innate immune response. Polymorphisms in the CARD15/NOD2 gene, in addition to functional variants of the toll-like receptor-4 (TLR4) and CD14 genes, have been associated with the development of Crohn’s disease. There is no information about the frequency of these polymorphisms in the Saudi population. We examined the frequency of the three major CARD15/NOD2 risk alleles (Leu1007fsinsC, Arg702Trp, and Gly908Arg) and the TLR4 (Thr399Il) polymorphism as well as a functional polymorphism in the promoter of the CD14–159C/T in 46 Saudi CD patients and 50 matched controls. Genotyping was performed by allele-specific PCR or by restriction fragment length polymorphism (PCR-RFLP) analysis. The mutant genotype frequencies of the Leu1007fsinsC, Arg702Trp and Gly908Arg in the patient group were 6.5, 21.7 and 6.5%, respectively, compared with frequencies of 0, 4 and 2%, respectively, in the control group. There were 15 patients who carried the mutant alleles for all three CARD15/NOD2 variants, Leu1007fsinsC, Arg702Trp and Gly908Arg, while none of the control candidates carried the three alleles. This genetic study provides evidence that the three major CARD15/NOD2 variant alleles and the CD14 –159C/T polymorphism are associated with Crohn’s disease (CD) susceptibility in the Saudi population; however, there is no evidence that the TLR4 (Thr399Il) or CARD15/NOD2 polymorphisms can be considered risk factors for Crohn’s disease.

Deep resequencing of GWAS loci identifies independent rare variants associated with inflammatory bowel disease

More than 1,000 susceptibility loci have been identified through genome-wide association studies (GWAS) of common variants; however, the specific genes and full allelic spectrum of causal variants underlying these findings have not yet been defined. Here we used pooled next-generation sequencing to study 56 genes from regions associated with Crohn's disease in 350 cases and 350 controls. Through follow-up genotyping of 70 rare and low-frequency protein-altering variants in nine independent case-control series (16,054 Crohn's disease cases, 12,153 ulcerative colitis cases and 17,575 healthy controls), we identified four additional independent risk factors in NOD2, two additional protective variants in IL23R, a highly significant association with a protective splice variant in CARD9 (P < 1 × 10(-16), odds ratio ≈ 0.29) and additional associations with coding variants in IL18RAP, CUL2, C1orf106, PTPN22 and MUC19. We extend the results of successful GWAS by identifying new, rare and probably functional variants that could aid functional experiments and predictive models.

A new category of autoinflammatory disease associated with NOD2 gene mutations

INTRODUCTION

Autoinflammatory diseases are characterized by seemingly unprovoked episodes of inflammation, without high titers of autoantibodies or antigen-specific T cells, and derive from genetic variants of the innate immune system. This study characterized a cohort of patients with similar phenotypes and nucleotide oligomerization domain 2 (NOD2) gene mutations.

METHODS

Diagnostically challenging patients with the following clinical and genetic characteristics were prospectively studied between January 2009 and April 2011: periodic fever, dermatitis, polyarthritis, serositis, negative serum autoantibodies and additional positive NOD2 IVS8+158 gene mutation. Genetic testing for gene mutations of NOD2, tumor necrosis factor receptor-associated periodic fever syndrome (TRAPS) and familial Mediterranean fever (FMF) was performed.

RESULTS

All seven patients with the disease were Caucasians, with four being male. The mean age at disease onset was 40.7 years and disease duration was 3.2 years. These patients characteristically presented with periodic fever, dermatitis and inflammatory polyarthritis. There were gastrointestinal symptoms in three patients, granulomas of the skin and gut in two, and recurrent chest pain in two, with one having pleuritis and pericarditis. Three patients had sicca-like symptoms. Five patients had increased acute phase reactants. All seven patients had negative tests for autoantibodies but carried the NOD2 gene mutation IVS8+158 with four having concurrent R702W mutation.

CONCLUSIONS

Our cohort may represent a new disease category of autoinflammatory disease with characteristic clinical phenotypes and genotypes. It may somewhat resemble pediatric Blau's syndrome.

What can we learn about biofilm/host interactions from the study of inflammatory bowel disease

OBJECTIVES

The aim of this review was to evaluate possible common pathogenic pathways and risk factors in inflammatory bowel disease (IBD) and periodontitis.

MATERIALS AND METHODS

A MEDLINE-PubMed research was conducted.

RESULTS

The pathogenesis of both diseases is multi-factorial leading to a substantial defect of the mucosal barrier, deregulation of the immune response and chronic inflammation of the mucosa. Environmental factors, particularly bacteria, are key factors in the pathogenesis of both diseases. Genetic predisposition is a key factor in the IBD pathogenesis, while a clear role of genetics in the pathogenesis of periodontitis is still unclear. The immune response in IBD is mediated by T lymphocytes as a consequence of a genetic trait associated with T-cell deregulation. On the other hand, in periodontitis plasma cells and lymphocytes are the predominant cells in the chronic inflammatory lesion, with the presence of B cells being proportionally larger than T cells.

CONCLUSION

IBD and periodontitis share several factors in their aetiology and pathogenesis, although they also have distinct characteristics.

NOD2 exonic variations in Iranian Crohn's disease patients

PURPOSE

The NOD2 gene is known to have a strong association with Crohn's disease, but different trends were reported in occurrence of NOD2 variants in distinct ethnicities. The aim of this study was to assess all exonic sequences of the NOD2 gene in Iranian Crohn's disease patients and healthy controls to identify any existing variation and evaluate their association with Crohn's disease.

METHODS

A total of 90 non-related Crohn's disease patients and 120 sex- and age-matched healthy controls of Iranian origin were enrolled in this study. The participants were referred to a tertiary center in a 2-year period (2006-2008). The exonic regions of the NOD2 gene were amplified by polymerase chain reaction and evaluated by direct sequencing.

RESULTS

A total of 21 sequence variations were identified among all exonic regions of the NOD2 gene, of which eight had an allele frequency of more than 5%. Eight new mutations (one in exon 2 and seven in exon 4) were observed. The three main variants (R702W, G908R, and 1007fs) showed allele frequencies of 13.3%, 2.2%, and 1.7%, respectively. Three new variations (P371T, A794P, and Q908H) and R702W mutation were significantly more frequent in Crohn's disease patients compared to controls.

CONCLUSIONS

Eight novel mutations were identified in the NOD2 exons, but the pathophysiological importance of these variants remains unclear. Iranian patients with their different genetic reservoirs may demonstrate some novel characteristics for disease susceptibility.

Evaluation of 22 genetic variants with Crohn's disease risk in the Ashkenazi Jewish population: a case-control study

Background

Crohn's disease (CD) has the highest prevalence among individuals of Ashkenazi Jewish (AJ) descent compared to non-Jewish Caucasian populations (NJ). We evaluated a set of well-established CD-susceptibility variants to determine if they can explain the increased CD risk in the AJ population.

Methods

We recruited 369 AJ CD patients and 503 AJ controls, genotyped 22 single nucleotide polymorphisms (SNPs) at or near 10 CD-associated genes, NOD2, IL23R, IRGM, ATG16L1, PTGER4, NKX2-3, IL12B, PTPN2, TNFSF15 and STAT3, and assessed their association with CD status. We generated genetic scores based on the risk allele count alone and the risk allele count weighed by the effect size, and evaluated their predictive value.

Results

Three NOD2 SNPs, two IL23R SNPs, and one SNP each at IRGM and PTGER4 were independently associated with CD risk. Carriage of 7 or more copies of these risk alleles or the weighted genetic risk score of 7 or greater correctly classified 92% (allelic count score) and 83% (weighted score) of the controls; however, only 29% and 47% of the cases were identified as having the disease, respectively. This cutoff was associated with a >4-fold increased disease risk (p < 10e-16).

Conclusions

CD-associated genetic risks were similar to those reported in NJ population and are unlikely to explain the excess prevalence of the disease in AJ individuals. These results support the existence of novel, yet unidentified, genetic variants unique to this population. Understanding of ethnic and racial differences in disease susceptibility may help unravel the pathogenesis of CD leading to new personalized diagnostic and therapeutic approaches.

The differences between American and Chinese patients with Crohn's disease

AIM

The effect of race on Crohn's disease (CD) remains uncertain. This study compared the characteristics of American white patients and Chinese patients with CD.

METHOD

A retrospective chart review was conducted for patients who required management of colorectal CD between 1985 and 2004 at either Cleveland Clinic Florida (CCF) or at the 301 Hospital in China. Data included a family history of CD, smoking history, location of the CD and histopathology.

RESULTS

The mean age of onset in the 153 patients was 29.8 ± 16.4 years for American white patients and 32.4 ± 15.3 years for Chinese patients (not significant). Sixty per cent of American white patients were women vs 37% of Chinese patients (P = 0.003). Twelve per cent of American white patients vs 1% of Chinese patients had a family history of CD (P = 0.016). American white patients had significantly higher rates of arthritis (32%vs 4%), abscess (19%vs 0%), rectal and perineal fistula (52%vs 0%), and disease involving the colon and rectum when compared with Chinese patients (all P < 0.05). American white patients had more colorectal sites involved and higher rates of extraintestinal diseases (40%vs 20%) than Chinese patients (all P < 0.05). Chinese patients had higher rates of ileocaecal disease (82%vs 52%) and deep ulcers (66%vs 24%) in the colorectum (all P < 0.001). There were no statistical differences in the incidence of smoking, perforation, intra-abdominal fistula, stenosis, bowel obstruction, toxic megacolon or granuloma formation.

CONCLUSION

This study found that colorectal CD had a more severe clinical presentation and pathological involvement in American white patients than in Chinese patients.

Risk factors and gene polymorphisms of inflammatory bowel disease in population of Zhejiang, China

AIM: To identify the risk factors and three single nucleotide polymorphisms (SNPs) of NOD2/CARD15 gene in inflammatory bowel disease (IBD) of the population in Zhejiang, China.

METHODS: A case-control study was conducted using recall questionnaire to collect data on demographic, socioeconomic, lifestyle characteristics and dietary behaviors from 136 determined IBD patients and 136 paired healthy controls. COX regression method was used to screen the statistically significant risk factors for IBD. The polymorphisms of NOD2/CARD15 gene Arg702Trp, Gly908Arg and Leu1007fsinsC were genotyped and further compared between 60 patients with IBD and 60 healthy controls by polymerase chain reaction and restriction fragment length polymorphism.

RESULTS: IBD occurred primarily in young and middle-aged people. The mean age for IBD patients was 42.6 years. The ratio of males to females was 1.23:1. COX regression indicated a higher statistical significance in milk, fried food and stress compared with the other postulated risk factors for IBD. None of the patients with IBD and healthy controls had heterozygous or homozygous SNPs variants.

CONCLUSION: Milk, fried food and stress are associated with increased risk of IBD. The common variants in NOD2/CARD15 gene are not associated with IBD in China’s Zhejiang population.

Clinical periodontal and microbiologic parameters in patients with Crohn's disease with consideration of the CARD15 genotype

BACKGROUND

Crohn's disease (CD) was reported to have oral manifestations. However, data on periodontal parameters and oral microbiology in CD are rare. Recent studies showed associations of variants in the caspase recruitment domain (CARD)15 gene with CD that are involved in the immune response toward bacterial products. Our aim is to investigate the periodontal status and prevalence of periodontal pathogens in patients with CD under consideration of the CARD15 polymorphism.

METHODS

Oral soft tissue alterations and periodontal parameters of 147 patients with CD were assessed. Subgingival plaque samples were analyzed for the periodontal pathogens Aggregatibacter actinomycetemcomitans (Aa; previously Actinobacillus actinomycetemcomitans), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf; previously T. forsythensis), Prevotella intermedia (Pi), and Campylobacter rectus (Cr ) using dot-blot hybridization. CARD15 genotyping was performed with the a polymerase chain reaction (PCR) based assay.

RESULTS

A total of 36.7% of patients had oral manifestations predominated by gingival swellings (27.2%) and hyperplastic lesions of the buccal mucosa (20.4%). The mean probing depth and mean clinical attachment level were 3.6 and 3.8 mm, respectively. A total of 57.8% of the patients had a Community Periodontal Index of Treatment Needs (CPITN) score 3, and 31.3% of had a CPITN score 4. The prevalence of Aa, Pg, Pi, Tf, and Cr was 76.9%, 62.6%, 79.6%, 64.6%, and 94.6%, respectively. Pi was significantly less frequent in carriers of CARD15 mutations compared to the wild type (69.7% versus 87.7%; P = 0.008). All other pathogens and clinical periodontal parameters did not differ significantly as to the CARD15 polymorphism.

CONCLUSIONS

Our findings suggest that patients with CD have an increased prevalence and moderate severity of periodontitis. The colonization of periodontal pathogens, in particular Cr, might be of particular value for the periodontal manifestation of CD. Although a modulating impact on periodontal microbiota can be supposed, our data do not support the role of CARD15 in oral symptoms and periodontal lesions in patients with CD.

Genetic dissection of inflammatory bowel disease: unravelling etiology and improving diagnostics

Over the past 10 years, remarkable advances in the mapping and identification of genes involved in susceptibility to inflammatory bowel disease have been witnessed. Most notable among these advances has been the discovery of variants in the CARD15, DLG5, SLC22A4 and SLC22A5 genes, which are associated with increased risk of inflammatory bowel disease or specifically Crohn's disease. These discoveries have provided critical new insights into the molecular pathophysiology of inflammatory bowel disease and the pathways wherein genetic and environmental factors such as enteric bacterial flora may interact to trigger immune dysregulation and intestinal inflammation. This review will outline the discovery of these inflammatory bowel disease-related genes, describe future prospects for further inflammatory bowel disease gene identification, and consider the impact of a genetic understanding of inflammatory bowel disease on future clinical practice.

Serologic investigations in children with inflammatory bowel disease and food allergy

The aim of the study was the evaluation of frequency and titre of IgA ASCA and IgG ASCA and p-ANCA, c-ANCA in children with IBD and occurrence of ASCA antibodies in relation to coexistence of FA. Patients and methods. The study comprised 95 children at the ages of 2 to 18 years. The diagnosis of IBD was established on the basis of Porto criteria. Tests of blood serum were performed in all children: IgA and IgG ASCA, p-ANCA, c-ANCA using ELISA method. Results. IgE-dependent FA was found in 32.5% children with UC and in 21% with CD. We did not observe any relation between the occurrence of FA and the frequency and ASCA titre. p-ANCA were significantly more frequent in the group of children with UC. The occurrence of ASCA antibodies was observed in 73.7% of children with CD, 17.5% with UC and almost 30% with allergic colitis. Conclusions. Patients with CD and the presence of ASCA revealed a significantly more frequent localization of lesions within the small bowel and a tendency towards older age. We observed a connection between the occurrence of antibodies and the examined mutations of gene NOD2/CARD15.

Genotyping for NOD2 genetic variants and crohn disease: a metaanalysis

BACKGROUND

Arg702Trp, Gly908Arg, and Leu1007fsinsC variants of the NOD2 gene (nucleotide-binding oligomerization domain containing 2; alias, CARD15) influence the risk of Crohn disease.

METHODS

We conducted a systematic review to examine whether Arg702Trp, Gly908Arg, and Leu1007fsinsC are equally important risk factors for Crohn disease. In addition, we used studies for which combined information from all genotypes was available to compare risks in simple heterozygotes, compound heterozygotes, and homozygotes. PubMed, EMBASE, and Web of Science were searched. Seventy-five articles (18 727 cases and 17 102 controls) met the inclusion criteria and contributed data to the metaanalyses.

RESULTS

The odds ratios per allele for Crohn disease were 2.2 (95% CI, 2.0-2.5) for Arg702Trp, 2.6 (2.2-2.9) for Gly908Arg, and 3.8 (3.4-4.3) for Leu1007fsinsC (z-test results: Arg702Trp vs Gly908Arg, P = 0.03; Arg702Trp vs Leu1007fsinsC, P < 0.001; Gly908Arg vs Leu1007fsinsC, P < 0.001). When all 3 genotypes were combined, odds ratios for Crohn disease were 2.4 (95% CI, 2.0-2.8) for simple heterozygotes, 9.0 (6.0-13.5) for compound heterozygotes, and 6.7 (4.1-10.9) for homozygotes, compared with noncarriers (z-test results: simple heterozygotes vs compound heterozygotes, P < 0.001; simple heterozygotes vs homozygotes, P < 0.001; compound heterozygotes vs homozygotes, P = 0.18).

CONCLUSIONS

The per-allele risk of Crohn disease was markedly higher for Leu1007fsinsC than for Arg702Trp and Gly908Arg. Combining all genotypes revealed the risks of Crohn disease for compound heterozygotes and homozygotes to be similar and markedly higher than for simple heterozygotes.

Association between entero-hepatic Helicobacter species and Crohn's disease: a prospective cross-sectional study

BACKGROUND

The pathogenesis of Crohn's disease (CD) involved microbial factors. Some Helicobacter species, the so-called entero-hepatic Helicobacters (EHH), can naturally colonize the intestinal surface and have been detected in humans. Aim To look for an association between CD and the presence of EHH DNA in intestinal biopsies.

METHODS

Two groups of patients were included prospectively in a multicentre cross-sectional study: CD patients with an endoscopic post-operative recurrence within 2 years following a surgical resection and controls screened for colorectal polyps or cancer. Intestinal biopsies were taken for Helicobacter culture and Helicobacter 16S DNA detection. If positive, the EHH species were identified with specific PCRs, sequencing and denaturing gradient gel electrophoresis.

RESULTS

In the 165 included patients (73 CD and 92 controls), Helicobacter cultures were negative. PCR was positive in 44% of CD and 47% of controls. After age-adjustment, CD was significantly associated with EHH in intestinal biopsies (OR = 2.58; 95%CI: 1.04-6.67). All EHH species detected were identified as Helicobacter pullorum and the closely related species Helicobacter canadensis.

CONCLUSION

Crohn's disease is associated with the presence of EHH species DNA in intestinal biopsies after adjustment for age. Whether these species play a role in the pathophysiology of CD remains to be determined.

Research progress in susceptibility genes of inflammatory bowel disease

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a group of non-specific chronic inflammatory conditions of the gastrointestinal tract with unknown complex etiology. Epidemiologic data indicate genetic contribution to IBD pathogenesis, which include familial aggregation, twin studies, racial and ethnic differences in disease prevalence. The most widely adopted approaches to identifying susceptibility genes in IBD include linkage studies, genome-wide association (GWA) studies and microarray. The first two technologies have confirmed NOD2, IL23R and other genes implicated in IBD pathogenesis and advances in microarray technology makes it possible to diagnose IBD at gene expression level. This article reviewed IBD related genes and introduced application of microarray to IBD research.

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.

Novel CARD15/NOD2 mutations in Finnish patients with Crohn's disease and their relation to phenotypic variation in vitro and in vivo

BACKGROUND

Three mutations (R702W, G908R, and 1007fs) of the CARD15/NOD2 gene associate with Crohn's disease (CD). Despite a strong linkage of CD to the inflammatory bowel disease (IBD) 1 region, only 16% of the Finnish CD patients carry 1 of these 3 mutations, pointing to the possibility of yet undetected founder mutations in the genetically isolated Finns. The aim of this study was to screen for CARD15 mutations in Finnish CD patients and to assess their functional consequences and relation to clinical phenotype.

METHODS

We performed CARD15 mutation screening in 240 CD probands. For functional studies, blood mononuclear cells were cultured alone or with muramyl dipeptide (MDP) and IL-8 levels were determined.

RESULTS

We identified 30 different variants, including 12 new ones. Allele frequencies for the R702W, G908R, and 1007fs mutations were 3.3%, 0.4%, and 4.8%, respectively. The 1007fs variant was the only 1 associated significantly with CD. Five novel variants (R38M, W355X, P727L, W907R, R1019X) were found in 5 patients. The biochemical nature of these new mutations, data obtained by cross-species comparisons, as well as low IL-8 production favors their pathogenic role. All 5 patients with novel mutations presented a complicated form of ileal or ileocolonic disease.

CONCLUSIONS

In conclusion, we identified 5 novel CARD15 mutations with an apparent pathophysiological role, but could not identify a putative Finnish founder mutation. It is still possible that regulatory mutations present in the flanking or intronic areas of the CARD15 gene contribute to the genetic susceptibility of CD. Homozygosity or compound heterozygosity for CARD15 gene mutations must be considered especially in complicated CD patients.

Ethnicity-related polymorphisms and haplotypes in the human ABCB1 gene

INTRODUCTION

The human multidrug resistance gene ATP-binding cassette B1 (ABCB1) codes for P-glycoprotein (P-gp), an important membrane-bound efflux transporter known to confer anticancer drug resistance as well as affect the pharmacokinetics of many drugs and xenobiotics. A number of single nucleotide polymorphisms (SNPs) have been identified throughout the ABCB1 gene that may have an effect on P-gp expression levels and function. Haplotype as well as genotype analysis of SNPs is becoming increasingly important in identifying genetic variants underlying susceptibility to human disease. Three SNPs, 1236C-->T, 2677G-->T and 3435C-->T, have been repeatedly shown to predict changes in the function of P-gp. The frequencies with which these polymorphisms exist in a population have also been shown to be ethnically related.

METHODS

In this study, 95 individuals representative of the entire ethnic make-up of the USA were compared with 101 individuals from an Ashkenazi-Jewish population. These individuals were analyzed by genomic sequencing and polymerase chain reaction, using restriction fragment length polymorphisms, to calculate their genotype frequencies.

RESULTS

A total of 25 SNPs were located in the exons of the ABCB1 gene. All of the polymorphisms identified were in parts of the ABCB1 gene product predicted to be intracellular, and 16 appear to be novel as compared with those listed by the National Center for Biotechnological Information. Frequencies of the 1236C-->T and 2677G-->T/A/C SNPs were similar for the US and Ashkenazi populations (64.2 and 60.4%, respectively for 1236C-->T [chi2: 0.30; p < or = 1]; 55.8 and 64.4%, respectively for 2677G-->T/A/C [chi2: 1.49; p < or = 1]), but were different for 3435C-->T (24.2% for the US population and 69.3% for the Ashkenazi population [chi2: 39.927; p < or = 0.001]). The 1236T/ 2677T/3435T haplotype occurred in 23.6% (standard error: 0.013) of the Ashkenazi population.

CONCLUSION

The SNP at location 3435C-->T plays a significant role in the ABCB1 gene. The haplotype and genotype analysis from these data may be used as a basis for studies on the relationship between ABCB1 genotypes and drug efficacy, drug toxicity, disease susceptibility or other phenotypes.

Prevalence of CARD15/NOD2 mutations in Caucasian healthy people

BACKGROUND

Crohn's disease (CD) has been associated with CARD15/NOD2 mutations in Caucasians. The R702W, G908R, and 1007fs mutations represent 82% of the mutated chromosomes. The relative risk of developing CD in homozygous or compound heterozygous people has been estimated as between 10 and 40 times that of the general population. This high risk may support the opinion that CARD15/NOD2 variants are strong CD risk factors at the individual and population levels.

SUBJECTS AND METHODS

The allele and genotype frequencies were calculated for the R702W, G908R, and 1007fs mutations in 3,575 Caucasian healthy controls recruited by 15 groups distributed on three continents. Geographic homogeneity was tested and the observed proportion of double mutants was compared with the expected value using chi2 tests.

RESULTS

The allele frequencies of the R702W, G908R, and 1007fs mutations were 4.3% (3.6-4.9), 1.2% (0.8-1.6), and 2.3% (1.8-2.8), respectively, with large geographic fluctuations of the G908R, 1007fs, and wild-type alleles (P<0.0001). At the population level, no simple relationship was observed between mutation frequencies and the disease incidences in the studied populations. At the individual level, no significant deficit of double-dose mutation carriers among healthy controls was found, providing strong evidence that the penetrances of the most at-risk genotypes are low.

CONCLUSION

Altogether, these data confirm that CARD15/NOD2 acts in interaction with other unknown risk cofactors.

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.

A population-based case-control study of CARD15 and other risk factors in Crohn's disease and ulcerative colitis

OBJECTIVES

Multiple established Crohn's disease (CD) and ulcerative colitis (UC) risk factors including family history, tobacco use, Jewish ethnicity, urban residency, and CARD15/NOD2 mutations have been evaluated singly and in hospital-based observational studies. The goal of this study was to assess the relative contributions of all these risk factors jointly in a nonreferral, population-based cohort derived from a population epidemiologic database.

METHODS

CD (N = 232) and UC (N = 121) subjects were ascertained from our population-based IBD Registry derived from Manitoba Health, the single provincial insurer. Healthy controls (HC) (N = 336) were recruited via a 10:1 mailing matched for age, sex, and postal code. Ethnicity, tobacco use, family history, residency, and CARD15/NOD2 genotype status were determined.

RESULTS

In both univariate analyses and analyses adjusted for all risk factors, CD was influenced independently by CARD15/NOD2 heterozygote and homozygote/compound-heterozygote status (adjusted odds ratios [OR] 3.7 and 40.0, respectively), Jewish ethnicity (OR 18.5), CD family history (OR 6.2), and smoking (OR 3.0 current and 1.7 ex-smoker, respectively). Penetrance for homozygote/compound-heterozygotes was 4.9%, heterozygotes 0.54%, and wild types 0.184%. Population attributable risk for CARD15 was 26.7% and current tobacco use was 46.8%. A tobacco-CARD15 interaction was not observed. UC was influenced by Jewish ethnicity (OR 37.1), and by family history (OR 2.6), ex-smoker status (OR 1.9), and CARD15/NOD2 heterozygote or homozygote/compound-heterozygote status (OR 1.9 and 6.4, respectively) in adjusted analyses only.

CONCLUSIONS

CARD15/NOD2, family history, smoking, and Jewish ethnicity are independent risk factors for CD. Examination of these risk factors together in a single population-based cohort has provided initial data for population epidemiological characterization and genetic counseling uses.

CARD15 in inflammatory bowel disease and Crohn's disease phenotypes: an association study and pooled analysis

BACKGROUND

Three major polymorphisms of the Caspase-Activation Recruitment Domain containing protein 15 gene have been described to be associated with Crohn's disease. Genotype-phenotype studies reported in literature provide conflicting data on disease localisation and behaviour. We investigated the relation of Caspase-Activation Recruitment Domain containing protein 15 with inflammatory bowel disease and Crohn's disease phenotypic characteristics in a large Dutch cohort and performed a pooled analysis on inflammatory bowel disease patients and Crohn's disease phenotypic characteristics reported in association studies.

METHODS

We genotyped 781 cases and 315 controls for the R702W, G908R and 1007fsinsC variants and for six microsatellite markers in and close to Caspase-Activation Recruitment Domain containing protein 15. In the pooled analysis data of 7201 inflammatory bowel disease patients and 3720 controls from 20 studies were included.

RESULTS

Association was found for Crohn's disease with R702W and 1007fsinsC, including several disease characteristics, and not for ulcerative colitis. In the pooled analysis all three common Caspase-Activation Recruitment Domain containing protein 15 variants showed strong association with Crohn's disease (p<0.00001; odds ratio varying from 3.0 for single heterozygotes to 14.7 for compound heterozygotes) and not with ulcerative colitis. Phenotype analysis showed association with small bowel involvement, stricturing and penetrating disease.

CONCLUSION

Caspase-Activation Recruitment Domain containing protein 15 is associated with Crohn's disease and not with ulcerative colitis. All three common Crohn's disease-associated variants are associated with small bowel involvement, the G908R and 1007fsinsC alleles also being associated with a complicated disease course.

CARD15 gene variants in aggressive periodontitis

OBJECTIVE

The CARD15 gene encodes a protein that acts as an intracellular receptor of bacterial products, thus playing an important role in the innate immune response. Recently, CARD15 gene variants have been identified as a cause of increased susceptibility to Crohn's disease. The present study aimed to examine a potential association of CARD15 gene variants with aggressive periodontitis susceptibility.

MATERIAL AND METHODS

The three main known CARD15 gene variants (p.R702W, p.G908R, and p.L1007fsX1008) were analysed by direct sequencing of exon 4, 8, and 11 of the gene in a total of 86 generalized aggressive periodontitis patients in comparison with 67 healthy controls.

RESULTS

The mutant allele frequencies of the CARD15 variants were low in the generalized aggressive periodontitis group as well as in the control group and not significantly different (R702W: 3.5% versus 5.2%; G908R: 1.7% versus 1.5%; L1007fsX1008: 5.2% versus 4.5%). Two rare variants (A755V and R791Q), previously described only in patients with other inflammatory diseases, were observed in three patients having aggressive periodontitis but not in controls.

CONCLUSIONS

Unlike in Crohn's disease, our results did not show an association between the three main CARD15 mutations and aggressive periodontitis. The role of rare variants remains unclear.

Identification of genetic loci for basal cell nevus syndrome and inflammatory bowel disease in a single large pedigree

Basal Cell Nevus Syndrome (BCNS) is an autosomal dominant disease. PTCH1 gene mutations have been found responsible in many but not all pedigrees. Inflammatory Bowel Disease (IBD) is a complex genetic disorder, disproportionate in Ashkenazim, and characterized by chronic intestinal inflammation. We revisited a large Ashkenazim pedigree, first reported in 1968, with multiple diagnoses of BCNS and IBD, and with a common genetic cause for both disorders proposed. We expanded the pedigree to four generations and performed a genome-wide linkage study for BCNS and IBD traits. Twelve members with BCNS, seven with IBD, five with both diagnoses and eight unaffected were genotyped. Both non-parametric (GENEHUNTER 2.1) and parametric (FASTLINK) linkage analyses were performed and a validation through simulation was performed. BCNS linked to chromosome 9q22 (D9S1120) just proximal to the PTCH1 gene (NPL=3.26, P=0.003; parametric two-point LOD=2.4, parametric multipoint LOD=3.7). Novel IBD linkage evidence was observed at chromosome 1p13 (D1S420, NPL 3.92, P=0.0047; parametric two-point LOD=1.9). Linkage evidence was also observed to previously reported IBD loci on 4q, (D4S2623, NPL 3.02, P=0.012; parametric two-point LOD=2.15), 10q23 (D10S1225 near DLG5, NPL 3.33, P=0.0085; parametric two-point LOD=1.3), 12 overlapping the IBD2 locus (D12S313, NPL 2.6, P=0.018; parametric two-point LOD=1.52), and 7q (D7S510 and D7S3046, NPL 4.06, P=0.0035; parametric two-point LOD=2.18). In this pedigree affected by both BCNS and IBD, the two traits and their respective candidate genetic loci segregate independently; BCNS maps to the PTCH1 gene and IBD maps to several candidate regions, mostly overlapping previously observed IBD loci.

Distribution of common CARD15 variants in patients with sporadic Crohn's disease: cases from Turkey

Three common genetic variations, namely, R702W, G908R, and 1007fs, on CARD15 have been shown to increase the risk for Crohn's disease (CD) in Caucasian populations. In this study the frequencies of these CARD15 variants were determined by genotyping in 56 patients with CD and 100 healthy ethnically matched controls from Turkey. Overall frequency of all three variants was 10.7% in CD patients, compared with 1.5% in controls (odds ratio [OR]: 7.9). Among them, the frequency of the G908R variant allele was 8% in CD cases, compared with 0% in controls (OR: 36.8). The allele frequencies of three CD-related CARD15 variants were considerably lower in the control group compared to the reported Caucasian populations. Among the described CARD15 variants, G908R confers an increased susceptibility to CD, whereas the more frequently reported associations in Europeans with R702W and 1007fs are not confirmed in this Turkish population.

Mutation, selection, and evolution of the Crohn disease susceptibility geneCARD15

Three common mutations in the CARD15 (NOD2) gene are known to be associated with susceptibility to Crohn disease (CD), and genetic data suggest a gene dosage model with an increased risk of 2-4-fold in heterozygotes and 20-40-fold in homozygotes. However, the discovery of numerous rare variants of CARD15 indicates that some heterozygotes for the common mutations have a rare mutation on the other CARD15 allele, which would support a recessive model for CD. We addressed this issue by screening CARD15 for mutations in 100 CD patients who were heterozygous for one of the three common mutations. We also developed a strategy for evaluating potential disease susceptibility alleles (DSAs) that involves assessing the degree of evolutionary conservation of involved residues, predicted effects on protein structure and function, and genotyping in a large sample of cases and controls. The evolutionary analysis was aided by sequencing the entire coding region of CARD15 in three primates (chimp, gibbon, and tamarin) and aligning the human sequence with these and orthologs from other species. We found that 11 of the 100 CD patients screened had a second potential pathogenic mutation within the exonic and periexonic sequences examined. Assuming that there are no additional pathogenic mutations in noncoding regions, our study suggests that most carriers of the common DSAs are true heterozygotes, and supports previous evidence for a gene dosage model. Four novel nonsynonymous mutations were detected, one of which would produce premature termination of translation c.2686C>T (p.Arg896X). Two potential DSAs--c.2107C>T (p.Arg703Cys) and g.2238T>A (c.74-7T>A)--were significantly associated with CD in the case control sample. Analysis of the evolution of CARD15 revealed strong conservation of the encoded protein, with identity to the human sequence ranging from 99.1% in the chimp to 44.5% in fugu. Higher primates possess an open reading frame (ORF) upstream of the putative initiation site in other species that encodes a further 27 N-terminal amino acids, while four regions of high conservation are observed outside of the known domains of CARD15, indicative of additional residues of functional importance. The strategy developed here may have general application to the assessment of mutation pathogenicity and genetic models in other complex disorders.

The relation between NOD2/CARD15 mutations and the prevalence and phenotypic heterogeneity of Crohn's disease: lessons from the Israeli Arab Crohn's disease cohort

The prevalence of Crohn's disease depends on geographic location and racial background. Arg702Trp, Gly908Arg, and Leu1007fsinsC mutations in the NOD2/CARD15 gene are associated with Crohn's disease in Caucasians. The mutation rate among Israeli Jewish patients is 27%-41%. The prevalence of Crohn's disease is much lower in the Israeli Arab compared to the Israeli Jewish population. We studied the NOD2/CARD15 mutation rate and disease phenotype (according to the Vienna classification) among the Israeli Arabs and compared them with those in an Israeli Jewish cohort. We recruited 66 Israeli Arab patients and 122 ethnically matched controls. Five patients (8.2%) and three controls (2.3%) carried one NOD2/CARD15 mutation. The phenotypic characteristics of the Arab and Jewish patients were very similar. We conclude that NOD2/CARD15 mutations do not contribute to Crohn's susceptibility in the Israeli Arab population and suggest that NOD2/CARD15 mutations have an important effect on Crohn's prevalence within a specific population but not on the phenotype.

Is age of onset of Crohn's disease governed by mutations in NOD2/caspase recruitment domains 15 and Toll-like receptor 4? Evaluation of a pediatric cohort

Crohn's disease (CD) is caused by a combination of environmental and genetic factors. It is not clear at present whether age of onset (AOO) is a random event or dictated by genotype or environmental factors. Mutations in the NOD2/caspase recruitment domains 15 (CARD15) and in the Toll-like receptor 4 (TLR4) gene have been associated with increased susceptibility for CD. We sought to determine whether single or multiple mutations in these genes are linked to earlier susceptibility for CD. A cohort of 189 patients with CD (82 pediatric onset, 107 adult onset) were genotyped for three disease-associated single-nucleotide polymorphisms (SNPs), one haplotype association (JW1-SNP5), and one background polymorphism (P268S) of the NOD2/CARD15 gene and for two SNPs of TLR4. Analysis of heterozygosity, homozygosity, alleles, and haplotypes of cohort on age or pediatric onset was performed. AOO ranged from 8 mo to 68 y. The presence of the three NOD2/CARD15 and two TLR4 mutations, the NOD2/CARD15 JW haplotype, compound heterozygosity, and homozygosity were not associated with AOO. Presence of P268S in the absence of known NOD2/CARD15 mutations was correlated with increasing age and adult onset of CD, whereas pediatric-onset disease was associated with male gender and the wild-type NOD2/CARD15 haplotype. Mutations in NOD2/CARD15 and TLR4 are not significantly associated with AOO in our population. Mutations that are not in linkage disequilibrium with the background mutation P268S of the NOD2/CARD15 gene probably play a more significant role in pediatric-onset disease.

Comparison of methods incorporating quantitative covariates into affected sib pair linkage analysis

For complex traits, it may be possible to increase the power to detect linkage if one takes advantage of covariate information. Several statistics have been proposed that incorporate quantitative covariate information into affected sib pair (ASP) linkage analysis. However, it is not clear how these statistics perform under different gene-environment (G x E) interactions. We compare representative statistics to each other on simulated data under three biologically-plausible G x E models. We also compared their performance with a model-free method and with quantitative trait locus (QTL) linkage approaches. The statistics considered here are: (1) mixture model; (2) general conditional-logistic model (LODPAL); (3) multinomial logistic regression models (MLRM); (4) extension of the maximum-likelihood-binomial approach (MLB); (5) ordered-subset analysis (OSA); and (6) logistic regression modeling (COVLINK). In all three G x E models, most of these six statistics perform better when using the covariate C1 associated with a G x E interaction effect than when using the environmental risk factor C2 or the random noise covariate C3. Compared with a model-free method without covariates (S(all)), the mixture model performs the best when using C1, with the high-to-low OSA method also performing quite well. Generally, MLB is the least sensitive to covariate choice. However, most of these statistics do not provide better power than S(all). Thus, while inclusion of the "correct" covariate can lead to increased power, careful selection of appropriate covariates is vital for success.

Differential effects of NOD2 variants on Crohn's disease risk and phenotype in diverse populations: a metaanalysis

OBJECTIVES

Three variants of the CARD15/NOD2 gene (SNP8, SNP12, and SNP13) have been associated with Crohn's disease (CD). We assessed the impact of NOD2 variants on the CD risk across diverse populations and examined possible associations with disease phenotype.

METHODS

We performed a metaanalysis searching MEDLINE and EMBASE (last search 05/2004) and contacting field experts.

RESULTS

Forty-two eligible studies contributed data on 206 comparisons. No variants were detected in Asians. In non-Jewish descent Caucasians carriage of SNP8, SNP12, or SNP13 had an odds ratio (OR) for CD of 2.20 (95% CI: 1.84-2.62), 2.99 (95% CI: 2.38-3.74), and 4.09 (95% CI: 3.23-5.18), respectively. For Jewish descent patients the corresponding ORs were 1.74, 1.93, and 2.45, respectively. The OR in carriers of at least two alleles was 17.1 (95% CI: 10.7-27.2). Large studies tended to yield more conservative estimates than smaller studies, so publication or other bias cannot be excluded. Among CD patients, carrying at least one high-risk variant increased slightly the risk for familial disease (OR = 1.49, (95% CI: 1.18-1.87)), modestly the risk of stenosing CD (OR = 1.94, (95% CI: 1.61-2.34)), and more prominently the risk of small bowel involvement (OR = 2.53, (95% CI: 2.01-3.16)).

CONCLUSIONS

SNP8, SNP12, and SNP13 have differential effects on CD risk, with SNP13 having the strongest genetic effect. These NOD2 variants are also significant risk factors for CD phenotype, in particular ileal location.