Identification of NOD2/CARD15 mutations in Malaysian patients with Crohn's disease

OBJECTIVE: The NOD2/CARD15 gene has been identified as an important susceptibility gene for Crohn's disease (CD) but the three common disease predisposing mutations (DPM) found in developed countries have not been identified in Asian populations. The aim of our study was to look for the DPM in our multiracial population and to discover whether there were any differences in the three major ethnic groups; Malay, Chinese and Indian. METHODS: Blood samples from consecutive CD patients and healthy controls were obtained and analyzed for the three common mutations (R702W, G908R, 1007fs) but in addition to this, we also looked for the SNP5 and JW1 variants which are associated with CD in Ashkenazi Jews. A polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) technique was used to identify the mutations, which was confirmed by sequencing. The baseline socio‐demography and clinical characteristics of the CD patients were recorded. RESULTS: Overall 45 patients (three Malays, 15 Chinese, 26 Indians and one other) with confirmed CD and 300 controls were recruited. The three common DPM were not observed in either the CD patients or the controls. Neither the SNP5 nor the JW1 mutation was found in any of the controls. However, the SNP5 mutation was identified in six (13.3%) Indian CD patients and the JW1 mutation in eight CD patients who are different from those carrying the SNP5 mutation: one Malay (33.3%), two Chinese (13.3%), one other (Portuguese) and four Indians (15.4%). The presence of SNP5 was strongly associated with CD in the Indian population and that of JW1 was strongly associated with CD overall and in each of the major ethnic groups. There was a trend towards a younger age of onset and stricturing disease in patients carrying the JW1 mutation. CONCLUSION: These findings suggest the presence of novel DPM in the NOD2/CARD15 gene in Asian patients with CD.     

Clinical applications of NOD2/CARD15 mutations in Crohn's disease

The recent identification of the CARD15/NOD2 gene as a susceptibility locus for Crohn's disease represents an important step in the immunopathogenesis of inflammatory bowel disease. The gene explains about 20% of the genetic susceptibility CARD15 mutations are present in 30-50% of CD patients compared to 7-20% of healthy controls. The three risk alleles R702W, G908R and 1007fsInsC in NOD2 associated with susceptibility to Crohn's disease have demonstrated a remarkable amount of heterogeneity across ethnicities and populations, with regional variation across Europe. In non-Caucasian populations Crohn's disease continues to increase in incidence but this increase appears not to be a consequence of variation in NOD2. Genotype-phenotype analyses demonstrated an association of these mutations with ileum-specific disease and an increased incidence of the fibrostenotic phenotype. Although CARD15 variants do not predict response to the TNF alpha monoclonal antibodies, there are no data available on the possible influence of CARD15 mutations on response to other drugs. Screening for CARD15 mutations in order to identify high-risk individuals or to introduce an individualized disease management is therefore currently not recommended.     

Toll-like receptor 4 and NOD2／CARD15 mutations in Hungarian patients with Crohn＇s disease： Phenotype-genotype correlations

AIM: To determine common NOD2/CARD15 mutations and TLR4 D299G polymorphism in Hungarian patients with CD. METHODS: A total of 527 unrelated patients with CD (male/female: 265/262, age: 37.1 (SD 7.6) years) and 200 healthy subjects were included. DNA was screened for possible NOD2/CARD15 mutations by denaturing high-performance liquid chromatography (confirmed by direct sequencing). TLR4 D299G was tested by PCR-RFLP. RESULTS: NOD2/CARD15 mutations were found in 185 patients (35.1%) and in 33 controls (16.5%,P<0.0001). SNP8/R702W (10.8% vs 6%, P= 0.02), SNP13/3020insC (19.4% vs 5%, P<0.0001) and exon4 R703C (2.1% vs 0%, P= 0.02) mutations were more frequent in CD, while the frequency of SNP12/G908R was not increased. The frequency of TLR4 D299G was not different (CD: 9.9% vs controls: 12.0%). Variant NOD2/CARD15 allele was associated with an increased risk for CD (ORhet=1.71, 95%CI=1.12-2.6, P= 0.0001, ORtwo-risk alleles = 25.2, 95%CI =4.37- ,P<0.0001), early disease onset (carrier: 26.4 years vs non-carrier: 29.8 years, P=0.0006), ileal disease (81.9% (?) 69.5%, OR = 1.99, 95%CI = 1.29-3.08, P= 0.02, presence of NOD2/CARD15 and TLR4: 86.7% vs 64.8%), stricturing behavior (OR = 1.69,95%CI = 1.13-2.55, P= 0.026) and increased need for resection (OR=1.71, 95%CI: 1.13-2.62, P= 0.01), but not with duration, extra-intestinal manifestations, familial disease or smoking. TLR4 exhibited a modifier effect: age of onset in wt/TLR4 D299G carriers: 27.4 years vs NOD2mut/TLR D299G: 23 years (P = 0.06), in NOD2mut/wt: 26.7 years. CONCLUSION: These results confirm that variant NOD2/ CARD15 (R702W, R703C and 3020insC) alleles are associated with earlier disease onset, ileal disease, stricturing disease behavior in Hungarian CD patients. In contrast, although the frequency of TLR4 D299G polymorphism was not different from controls, NOD2/TLR4 mutation carriers tended to present at earlier age.     

NOD2/CARD15 gene polymorphisms in Crohn's disease: a genotype-phenotype analysis in Danish and Portuguese patients and controls

BACKGROUND: A North-South gradient in Crohn's disease (CD) implying a higher incidence in northern Europe compared to southern Europe has been established. AIMS: To investigate whether there is a difference between Denmark and Portugal in the frequency of CARD15 mutations in CD patients compared to a healthy background population and to compare genotype-phenotype relations in the two countries. METHODS: 58 Danish patients and 29 Portuguese patients with CD were matched for age, sex and disease behaviour at time of diagnosis and compared with 200 healthy Danish and Portuguese controls. Phenotypes were recorded at year of diagnosis, 3 years after diagnosis and at end of follow-up. Patients were genotyped for Arg702Trp, Gly908Arg and Leu1007InsC. RESULTS: 22% of the Danish patients vs. 9% of Danish controls compared to 21% of the Portuguese patients vs. 16% had at least one mutation. Mutation rates in Danish patients were significantly different (p=0.02) compared with Danish controls, no difference (p=0.51) was found between Portuguese patients and controls. However, a possible relationship between CD and presence of genetic mutations was found when comparing the two countries (p=0.03) using the Mantel-Haenszel test. No difference in evolution of phenotypes and the CARD15 status in CD was found during follow-up between the two matched populations. Ileal disease correlated to high occurrence of CARD15. CONCLUSION: No North-South gradient regarding occurrence of CARD15 was revealed. Although a trend towards more mutations in the Portuguese controls was seen, a relationship between CD and CARD15 mutations was observed in both countries.     

Association of NOD2/CARD15 mutations with previous surgical procedures in Crohn's disease.

OBJECTIVE: The aim of this study is to assess the importance of NOD2/CARD15 gene mutations as prognostic factors for surgical indications in Crohn's disease. PATIENTS AND EXPERIMENTAL DESIGN: A total of 165 Crohn s disease patients were studied, considering previous surgery related to Crohn's disease. We analyzed for previous surgery in global procedures as well as separately for the two main surgical indications: ileal resection and fistula treatment. The need for appendectomy was also studied. All patients were genotyped for the three CARD15 mutations, and association studies were developed using Chi-square statistics and Fisher's exact test whenever appropriate. RESULTS: Carriers of the G908R or 1007fs mutation needed surgery more frequently, both for ileal resection and fistula repair. In contrast, appendectomy was not associated with CARD15 mutations. CONCLUSIONS: As previously reported in this population, the R702W mutation does influence parameters of disease or need of surgery. The need for Crohn's disease-related surgery is higher in carriers of the G908R or 1007fs CARD15 mutation in the Galician population. Nevertheless, the frequency of these mutations does not allow their use to predict the course of disease.     

NOD2/CARD15 disease associations other than Crohn's disease

At this moment, few confirmed associations between NOD2 mutations and diseases other than Crohn's disease (CD) and Blau syndrome (BS) have been reported, but research is ongoing in several fields where a genetic susceptibility factor and/or a role for the innate immune system is suspected. Whether the Crohn's-associated CARD15 mutations lead to a loss or gain of function of the NOD2 receptor is subject to controversy, and by which mechanisms this change in function might increase the susceptibility to CD is still under investigation. The possible involvement of NOD2/CARD15 in the pathogenesis of certain diseases with already (partially) unraveled pathophysiologic mechanisms might contribute to our further understanding of NOD2/CARD15 and its function in CD. We review studies on the association of CARD15 variants with diseases other than CD. The association of NOD2/CARD15 mutations with CD and BS, and possibly also early onset sarcoidosis, suggests a role for the gene in the development of granulomata and granulomatous diseases, possibly by inappropriate activation of the immune system. The data from the oncology field suggest that this inappropriate activation might even lead to uncontrolled proliferation of certain cell types. The studies in allergic diseases and atopy are the largest so far, and the association of NOD2/CARDI5 mutations with atopic phenotypes might be an indication that CARD15 also plays a role in the Th2 pathway. Finally, transplantation studies indicate that the genetic background of a patient should be taken into account when considering hematopoietic stem cell transplantation, given the increased risk of mortality and graft versus host disease observed. Whether NOD2 variants are also associated with an increased risk for infections and sepsis in patients receiving immunosuppressive therapies is unclear.     

NOD2/CARD15 mutations and presence of granulomas in pediatric and adult Crohn's disease

OBJECTIVES: The etiology and mechanism leading to granuloma formation in patients with Crohn's disease (CD) are presently unknown. The first susceptibility gene to be identified as a risk factor for CD is the NOD2/CARD15 gene on Chromosome 16. Mutations in NOD2 could affect the intracellular response to bacterial products and may eventually lead to granuloma formation. The association between NOD2 and granulomas has not been previously explored. We evaluated a possible association between NOD2 mutations and granuloma formation, and compared the prevalence of granulomas in both pediatric and adult cohorts. METHODS: Patients were consecutively recruited through pediatric gastroenterology and adult gastroenterology programs. Patients were eligible if CD was confirmed, and they had undergone full colonoscopy with biopsy and/or surgical resection. Patients underwent genotyping for NOD2 disease-associated mutations. RESULTS: A total of 230 patients were enrolled into the study, of whom 169 patients met all inclusion/exclusion criteria (Group 1, 77 patients [age range 1-16 years]; Group 2, 92 patients [age range 17-68 years]). Surgical resection was performed more often in adults (P < 0.005), and gastroscopy was performed more frequently in children (P < 0.001). Granulomas were found in 34% of the patients studied. The prevalence of granulomas did not differ by age, age group, or gender. A disease-associated NOD2 mutation was found in 37.8% of patients. Granulomas were found in 39% of patients with NOD2 mutations compared with 31% of those without NOD 2 mutations (difference was not significant). In addition, no difference was noted for the specific mutations. CONCLUSIONS: We did not find any correlation between NOD2 mutations and granuloma formation. The cause of granulomas in CD remains elusive.     

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.     

NOD2/CARD15 gene mutations in North Algerian patients with inflammatory bowel disease

AIM: To analyse allelic frequency of NOD2 gene variantsand to assess their correlation with inflammatory bowel disease(IBD) in Algeria.METHODS: We studied 132 unrelated patients diagnosed with IBD, 86 with Crohn's disease(CD) and 46 with ulcerative colitis(UC). Data was prospectively collected between January 2011 and December 2013. The demographic and clinical characteristics were recorded for all the patients. A group of 114 healthy unrelated individuals were selected as controls. All groups studied originated from different regions of North Algeria and confirmed the Algerian origin of their parents and grandparents. Informed and written consent was obtained from each of the participants. All individuals were genotyped for the three CDassociated NOD2 variants(p.Arg702 Trp, p.Gly908 Arg and p.Leu1007 fsins C mutations) using the polymerase chain reaction-restriction fragment length polymorphism method. Allele and genotype frequencies in patients and control subjects were compared by χ2 test and Fisher's exact test where appropriate. Odds ratios(OR) and 95% confidence intervals(95%CI) were also estimated. Association analyses were performed to study the influence of these variants on IBD and on clinical phenotypes.RESULTS: The p.Arg702 Trp mutation showed the highest frequency in CD patients(8%) compared to UC patients(2%)(P = 0.09, OR = 3.67, 95%CI: 0.48-4.87) and controls(5%)(P = 0.4, OR = 1.47, 95%CI: 0.65-3.31). In CD patients allelic frequencies of p.Gly908 Arg and p.Leu1007 fsins C variants compared to HC were 3% vs 2%(P = 0.5, OR = 1.67, 95%CI: 0.44-6.34); 2% vs 1%(P = 0.4 OR = 2.69 95%CI: 0.48-14.87 respectively). In UC patients, allelic frequencies of p.Gly908 Arg and p.Leu1007 fsins C variants compared to HC were 1% vs 2%(P = 1, OR = 1.62, 95%CI: 0.17-4.74) and 2% vs 1%(P = 0.32, OR = 0.39, 95%CI: 0.05-2.87). The total frequency of the mutated NOD2 chromosomes was higher in CD(13%), than in HC(8%) and UC(5%). In addition, NOD2 variants were linked to a particular clinical sub-phenotype in CD in this Algerian cohort. As expected, the three NOD2 variants showed a significant association with CD but did not reach statistical significance, despite the fact that the allele frequency of NOD2 variants was in the range found in most of the European populations. This might be due to the non-exposure of the NOD2 carriers to environmental factors, required for the expression of the disease.CONCLUSION: Further analyses are necessary to study genetic and environmental factors in IBD in the Algerian population, using larger patient groups.     

NOD2／CARDl5基因突变与中国人克罗恩病相关性研究

背景NOD2／CARDl5基因是人类克罗恩病（Crohn＇s disease，CD）第一个易感基因，既往研究发现P268S可能与中国人CD发病及临床特征相关。目的本研究旨在证实P268S与中国人CD发病及其临床特征的相关性。方法血样来自临床确诊的50例CD患者，60例溃疡性结肠炎（ulcerativecolitis，uc）患者及100例健康体检者（healthy controls，HC）。提取人血白细胞基因组DNA．PCR扩增目的片段，PCR—RFLP发现突变位点，DNA测序证实突变位点。结果共有8例CD患者发现有P268S改变，而在UC患者和HC中分别发现2例和3例P268S改变，CD组明显高于UC和HC组（X^2=10．829，P=0．004），而UC组和HC组无明显差异。8例有P268S改变的CD患者临床特征包括病变多位于回肠．发病年龄轻（6例〈20岁），常并发肠腔狭窄而需手术治疗，中一重度患者比例高。结论P268S可能是NOD2/CARDl5基因中与中国人CD相关的SNP。P268S与CD患者发病年龄、病变部位及并发症及病情严重程度可能相关。     

Association of NOD2/CARD15 variants with Crohn's disease in a Greek population

OBJECTIVE: Single nucleotide polymorphisms in the NOD2/CARD15 gene have recently been shown to be associated with Crohn's disease (CD), but whether this susceptibility extends to all ethnic groups and geographic areas remains unknown. The aim of the present study was to evaluate the NOD2/CARD15 mutations in Greek patients with CD. METHODS: Individuals were genotyped for three NOD2/CARD15 mutations: R702W, G908R and L1007fsinsC. Blood samples were obtained from 120 patients with CD, 85 patients with ulcerative colitis, and 100 unrelated healthy controls. RESULTS: Mutations in NOD2/CARD15 were observed with significantly greater frequency in CD patients (98/120, 81.7%) than in ulcerative colitis patients (40/85, 47%) (P < 0.0001) or in healthy individuals (21/100, 21%) (P < 0.0001). For CD patients, compared with controls, the odds were increased for carriage of the R702W (odds ratio, 12.25) and less for the G908R (odds ratio, 5.2) and L1007fsinsC (odds ratio, 3.9) mutations. The age of onset of CD was lower in Greek mutation carriers as compared with non-carriers of Greek origin (28.2 +/- 14.6 years versus 34 +/- 12.3 years, respectively; P = 0.036). Additionally, the frequency of NOD2/CARD15 mutations was increased in ileitis or ileocolitis compared with non-ileal disease. CONCLUSIONS: The NOD2/CARD15 mutations are risk factors for CD in Greece, they appear to predict an earlier age of onset and are associated particularly with ileitis or ileocolitis.     

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.     

NOD2/CARD15 gene polymorphisms in Crohn's disease: a genotype- phenotype analysis

OBJECTIVES: Three recently identified NOD2/CARD15 mutations have been described associated with an increased susceptibility Crohn's disease (CD). Our aim was to examine the potential association of these NOD2 mutations with CD and different subsets of CD phenotypes in our population. METHODS: Two hundred and five well-defined CD patients from north-western France and 95 ethnically matched healthy controls were genotyped for mutations R702W, G908R and Leu1007insC by DNA sequencing. Allele and genotype frequencies of NOD2 variants were examined in the whole series of CD and in different subgroups of CD phenotypes defined by the clinical characteristics of the Vienna classification (age at diagnosis, location and behaviour) or by histological features (granuloma). RESULTS: Carriers of at least one NOD2/CARD15 variant were significantly more frequent in CD than in controls (38.0% versus 20.0%, P < 0.002), and the R702W allele was the most significant contributor to this NOD2 association with CD. Homozygotes and compound heterozygotes combined had a higher risk of CD (odds ratio = 12.0, P < 0.0026) than simple heterozygotes for any variant (odds ratio = 2.2, P < 0.013) compared with subjects with no variant. Univariate analysis revealed that carriage of at least one NOD2 mutation was significantly associated with ileal involvement (P < 0.03), and stricturing evolution (P < 0.0015). Granuloma was associated with an excess of the R702W allele (16.1% versus 8.0%, Pc < 0.035), and was correlated with a young age at diagnosis, whatever the NOD2/CARD15 genotype. Multivariate analysis demonstrated that carriage of NOD2/CARD15 mutants, especially R702W, was primarily and independently associated both with stricturing evolution of CD and the presence of granuloma. CONCLUSIONS: In our population, all NOD2/CARD15 mutant genotypes, especially compound heterozygosity, were found to increase the risk of CD, but R702W was the sole allele showing a significant association with CD. In addition, we confirm the positive and independent association of the R702W mutation with stricturing behaviour and describe a second one with the presence of granuloma.     

NOD2/CARD15 does not influence response to infliximab in Crohn's disease

BACKGROUND & AIMS: NOD2/CARD15 was recently identified as the first gene underlying Crohn's disease (CD) susceptibility. Monoclonal antibodies to tumor necrosis factor (TNF)-alpha (infliximab) are a potent treatment for CD, with about 70% of patients responding. It is not clear which factors influence treatment outcome. We assessed whether variants in NOD2/CARD15 are predictive for differences in clinical response. METHODS: Two hundred forty-five CD patients (86 fistulizing, 159 luminal) receiving infliximab in an expanded access program were genotyped for the 3 main associated variants of NOD2/CARD15, without knowledge of the treatment response. Short-term clinical response was assessed at 4 weeks (refractory) or 10 weeks (fistulizing) after first infliximab infusion, and the mean duration of response was calculated. In a subgroup of patients, production of TNF in response to lipopolysaccharide (LPS) in mucosal biopsy tissue was also determined by means of immunoassay, and results were related to the different NOD2/CARD15 genotypes. RESULTS: In total, 32.6% of patients carried mutations in NOD2/CARD15 (18.8% R702W, 8.6% G908R, and 10.2% 1007fs) compared with 15% in controls (P < 0.001). Despite observed differences in TNF production in mucosal biopsy tissue, there was no relationship between the overall presence of a mutation in NOD2/CARD15 or of any of the mutations separately and short-term infliximab response or response duration. Furthermore, multivariate analysis could not identify clinical characteristics that, in combination with NOD2/CARD15 mutations, were associated with response to infliximab. CONCLUSIONS: In this cohort of CD patients, the frequency of NOD2/CARD15 mutations was significantly greater than that of healthy controls. However, NOD2/CARD15 was not predictive of treatment outcome with infliximab in CD.