Steroid Administration and Growth Impairment in Children with Crohn's Disease.

BACKGROUND: Growth impairment remains a major concern in children with Crohn's disease, but evidence remains unclear, in particular, whether steroid use is implicated. We aimed to (1) determine the frequency of temporary (TGI) and permanent (PGI) growth impairment in children administered steroids and (2) examine whether cumulative steroid administration was associated with TGI and/or PGI. METHODS: A retrospective cohort study was performed in patients with Crohn's disease (<18 yr) administered steroids at the gastroenterology clinics of Sainte-Justine Hospital, Montreal. Steroid dosage, height during follow-up, adult height (after age 20), and parental heights were ascertained. Patients with height z score <-1.64 on more than 1 occasion before age 18 were considered as patients with TGI. Patients with adult heights <8.5 cm below the expected target heights were considered as patients with PGI. Association between steroid dosage and TGI/PGI was studied using logistic regression analyses. Data from the Swiss IBD Cohort Study were analyzed for comparison. RESULTS: A total of 221 children were studied. Approximately 19% (42/221) children were deemed as TGI, and 8/137 patients (5.8%) had PGI. TGI was associated with diagnosis at younger age (P value 0.002) and steroid administration at younger age (P value 0.001), but not with steroid dosage. Final adult height was associated with target height, but not with cumulative steroid dosage. Rates of PGI in the Swiss cohort were ∼ 9.1% in steroid users and 2.7% in nonusers. CONCLUSIONS: Most children with TGI attain normal adult heights. Cumulative steroid use does not seem to be associated with either TGI or PGI in children with Crohn's disease.

Incidence of malignant mesothelioma of the pleura in Québec and Canada from 1984 to 2007, and projections from 2008 to 2032.

BACKGROUND: Continuous increase in male incidence of malignant mesothelioma of the pleura (MMP) despite the drop of asbestos production since 1980 in Québec motivated this study aiming to assess when the rates of MMP will decline. METHODS: Age-standardized rates and trends were estimated over the 1984-2007 period by sex for Québec versus "Canada-excluding-Québec" (Can-Qc). An age-cohort regression was used to make projections for 2008-2032. RESULTS: Average rates of MMP in Québec men and women were significantly higher than in Can-Qc. Projected rates peak between 2003 and 2012 in all four study populations and decline thereafter. CONCLUSION: The higher MMP rates and observed/projected time patterns in Québec men are consistent with past asbestos production and occupational exposures. The excess in Québec women may also be explained by domestic and, for some, by neighborhood exposures. To pursue the decrease in MMP rates beyond 2032, efforts to reduce asbestos exposure should be maintained.

Timing, frequency and type of physician-diagnosed infections in childhood and risk for Crohn's disease in children and young adults.

BACKGROUND: Recent experimental data show that exposure to microbes during early childhood can confer immunological tolerance and protect against Crohn's disease (CD). Epidemiological evidence for this link, however, remains controversial. Using prospective data, we examined the link between this hypothesis and risk for CD in children and young adults. METHODS: A case-control study design was used. CD cases (diagnosed before age 20 years) were recruited from a tertiary-care pediatric hospital in Montreal, and population-based controls matched for age, gender and, geographical location were selected. Infection data were ascertained from physician-billing records. These records, which use International Classification of Diseases, Ninth Revision diagnostic codes, were consulted retrospectively but provide prospectively collected diagnostic information. Conditional logistic regression analysis was used to study potential associations. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated. RESULTS: Four hundred nine cases and 1621 controls were included. Regression analysis adjusting for potential confounding variables suggested that any recorded infection before the diagnosis of CD was associated with reduced risk of CD (OR, 0.67; 95% CI, 0.48-0.93). The protective effect was restricted to infections occurring mainly before 5 years of age, with increasing number of infections resulting in greater protection (1-5 infections: OR, 0.74; ≥6 infections: OR, 0.61; P value for trend = 0.039). Infections affecting the oral and upper respiratory tracts, cellulitis, and, enteric infections seemed most protective. CONCLUSIONS: Our study provides support for the hygiene hypothesis, whereby exposure to infections in early childhood could potentially reduce risks of CD.

Genome-wide association study signal at the 12q12 locus for Crohn's disease may represent associations with the MUC19 gene.

BACKGROUND: Genome-wide association studies (GWAS) in Crohn's disease (CD) have identified associations with single-nucleotide polymorphism (SNP) rs11175593 at chromosome 12q12. The MUC19 and LRRK2 genes reside close to the GWAS signal, but it is as yet unclear which of the 2 genes represent the CD susceptibility genes. METHODS: We studied associations between nonsynonymous coding variants in the MUC19 (5) and LRRK2 (3) genes in a case-control sample comprising CD cases aged <18 years at diagnosis. The GWAS lead SNP rs11175593 was also investigated. Allelic, genotype, and haplotype associations were examined assuming different models of inheritance. RESULTS: A total of 530 cases and 600 controls were studied. The mean (±SD) age at diagnosis was 12.4 (±3.3). Most cases were male (57.4%). Most patients had ileocolonic disease location (48.8%) and inflammatory behavior at diagnosis (87.0%). Three MUC19 SNPs were nominally significantly associated with CD (rs11564245, Asp→His: P = 0.02; rs4768261, Ser→Phe: P = 0.0008; and rs2933353, Glu→Ala: P = 0.01). Associations with rs4768261 were maintained after corrections for multiple comparisons (permuted, P = 0.007). None of the LRRK2 SNPs were associated with CD. Haplotype analysis supported the single SNP associations noted with the MUC19 gene. CONCLUSIONS: GWAS signal at chromosome 12q12 for CD may represent associations with the MUC19 gene.

Association between the PTPN2 gene and Crohn's disease: dissection of potential causal variants.

BACKGROUND: Although genome-wide association studies (GWAS) and subsequent meta-analyses have confirmed associations between the PTPN2 (protein tyrosine phosphatase, nonreceptor type 2) gene and Crohn's disease (CD), the potential causal variants remain unidentified. We aimed to dissect potential causal CD-associated PTPN2 variants, assess their functional significance, and relate PTPN2 protein expression with inflammation in CD. METHODS: A 3-stage study was carried out. In stage 1, we genotyped tagging single nucleotide polymorphisms (tag-SNPs) in the PTPN2 gene in a sample of patients with CD (<20 years, n = 556) and controls (n = 602). In stage 2, we resequenced the putative promoter, target exons and introns in the PTPN2 gene, and examined associations with high-frequency variants with CD in the stage 1 cohort. In stage 3 we studied the relationship between PTPN2 protein expression and mucosal inflammation and carried out in silico analyses to study the functional characteristics of the PTPN2 CD-associated SNPs. RESULTS: In stage 1, we observed associations between 5 intronic SNPs and CD including rs1893217 (P = 2 × 10⁻4), the SNP that is in perfect linkage disequilibrium with the lead genome-wide association studies SNP rs2542151. Resequencing revealed 2 known promoter polymorphisms. No associations between these promoter SNPs and CD were evident. In silico analyses revealed that the 5 associated intronic SNPs influenced PTPN2 expression and binding to important transcription factors. PTPN2 protein was overexpressed in inflamed intestinal tissues of patients with CD. CONCLUSIONS: Our findings suggest that noncoding variation in the PTPN2 gene may represent the causal variations influencing susceptibility for CD.

NELL1, NCF4, and FAM92B genes are not major susceptibility genes for Crohn's disease in Canadian children and young adults.

BACKGROUND: Genome-wide association studies (GWAS) and replication studies have shown conflicting associations between the NELL1, NCF4, and FAM92B genes and susceptibility for Crohn's disease (CD). We sought to examine whether these genes were associated with CD in Canadian children and young adults. METHODS: A case-control study was carried out at three pediatric gastroenterology clinics across Canada. Patients, ≤20 years at diagnosis, along with controls representative of the general population were selected. Study subjects were genotyped for 22 single nucleotide polymorphisms (SNPs) across the target genes. Allelic and haplotype associations were examined. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated. RESULTS: In all, 566 CD cases and 602 controls were investigated. The mean (±SD) age of the patients was 12.3 (±3.3) years. Most patients were male (57.8%), of Caucasian ancestry (98.2%), and had ileocolonic disease location (48.8%). Barring nominal associations with one FAM92B SNP, none of the other 21 SNPs analyzed were associated with CD either at the allelic or haplotype level. Separate analysis for ileal CD (L1 plus L3) also did not reveal significant associations with any of the SNPs. Similarly, a pooled analysis using data from two recent studies did not demonstrate associations between the NCF4 (OR = 1.10, 95% CI = 0.91-1.32, P = 0.32) and FAM92B (OR = 1.05, 95% CI = 0.95-1.17, P = 0.36) GWAS lead SNPs and ileal CD. CONCLUSIONS: GWAS-reported associations in the NELL1, NCF4, and FAM92B genes could not be replicated in Canadian children and young adults. Further investigation in other populations will be required to confirm the presence/absence of associations, if any.

Associations between variants in the ABCB1 (MDR1) gene and corticosteroid dependence in children with Crohn's disease.

BACKGROUND: Corticosteroids (CS) effectively induce remission in patients with moderate to severe Crohn's disease (CD). However, CS dependence in children is a significant clinical problem associated with numerous side effects. Identification of molecular markers of CS dependence is of paramount importance. The ABCB1 gene codes for P-glycoprotein, a transporter involved in the metabolism of CS. We examined whether DNA variation in the ABCB1 gene was associated with CS dependency in children with CD. METHODS: A retrospective study was carried out in two Canadian tertiary pediatric gastroenterology centers. Clinical information was abstracted from medical charts of CD patients (N = 260) diagnosed with CD prior to age 18 and administered a first course of CS during the 1 year since diagnosis. Patients were classified as CS-dependent if they relapsed during drug tapering or after the end of therapy. DNA was extracted from blood or saliva. Thirteen tagging single nucleotide polymorphisms (tag-SNPs) and a synonymous variation (C3435T) in the ABCB1 gene were genotyped. Allelic, genotype, and haplotype associations were examined using logistic regression and Haploview. RESULTS: Tag-SNP rs2032583 was statistically significantly associated with CS dependency. The rare C allele of this SNP (odds ratio [OR] = 0.56, 95% confidence interval [CI]: 0.34-0.95, P = 0.029) and heterozygous genotype TC (OR = 0.52, 95% CI: 0.28-0.95, P = 0.035) conferred protection from CS dependency. A three-marker haplotype was significantly associated with CS dependence (multiple comparison corrected P-value = 0.004). CONCLUSIONS: Our results suggest that the ABCB1 gene may be associated with CS dependence in pediatric CD patients.

Variation in the glucocorticoid receptor gene (NR3C1) may be associated with corticosteroid dependency and resistance in children with Crohn's disease.

OBJECTIVES: In pediatric onset of Crohn's disease (CD), corticosteroid dependency (approximately 40%) and resistance (approximately 10%) are significant clinical problems. Given the known effects of the glucocorticoid receptor (GR/NR3C1) gene in corticosteroid metabolism, we investigated whether variation in the gene was associated with corticosteroid response. METHODS: A retrospective cohort study was carried out including patients with CD diagnosed before 18 years and treated with a first course of corticosteroids in two Canadian tertiary pediatric gastroenterology clinics. DNA was obtained from blood or saliva. Tagging single nucleotide polymorphisms (SNPs) and functionally important SNPs were genotyped. Allelic, genotype, and haplotype associations between the glucocorticoid receptor SNPs and response to corticosteroids were examined. RESULTS: A total of 296 corticosteroid-resistant, corticosteroids-dependent, and corticosteroid-responsive patients with CD were studied. Of the 12 SNPs examined, four markers, rs6196 [odds ratio (OR)=2.03; 95% confidence interval (CI): 1.03-4.0; P=0.042], rs7701443 (OR=3.43; 95% CI: 1.79-6.57; P=0.042), rs6190 (OR=4.84; 95% CI: 1.70-13.80; P=0.003), and rs860457 (OR=3.43; 95% CI: 1.79-6.57; P<0.001) were associated at the allelic level with corticosteroid resistance. Haplotype analysis of four associated markers revealed associations between two haplotypes and corticosteroid resistance (P values of 0.046 and 0.001). Three SNPs, rs10482682 (OR=1.43; 95% CI: 0.99-2.08; P=0.047), rs6196 (OR=0.55; 95% CI: 0.31-0.95; P=0.024), and rs2963155 (OR=0.64; 95% CI: 0.42-0.98; P=0.039), showed associations under an additive model, whereas rs4912911 (OR=0.37; 95% CI: 0.13-1.00; P=0.03) and rs2963156 (OR=0.32; 95% CI: 0.07-1.12; P=0.047) showed associations under a recessive model with corticosteroid dependence. Two five-marker haplotypes were associated with corticosteroid dependence (P values 0.002 and 0.004). CONCLUSION: Our results suggest that variations in the GR/NR3C1 gene are associated with corticosteroid resistance and dependency in pediatric-onset CD. Studies are required to replicate these findings and to identify the potentially relevant variants.

Immediate and long-term outcomes of corticosteroid therapy in pediatric Crohn's disease patients.

BACKGROUND: Although a mainstay of treatment of moderate to severe Crohn's disease (CD), corticosteroids use presents significant challenges because of large interindividual variability in response. Corticosteroid-dependence is of particular concern in children, where high rates have been reported. We examined the burden of corticosteroid-resistance and dependence in a well-characterized cohort of pediatric CD patients and investigated potential predictors of response. METHODS: Children diagnosed with CD (<18 years), were recruited from two Canadian pediatric gastroenterology clinics. Immediate and long-term responses to corticosteroid therapy were retrospectively ascertained. Response rates (resistance and dependence) were estimated and potential predictors assessed using logistic regression analysis. RESULTS: Of the 645 CD patients, 364 (56.2%) received corticosteroids. The frequency of corticosteroid-resistance was (8.0%) (95% confidence interval [CI]: 5.0%-11%) and 40.9% (95% CI: 39.0%-46.0%) became dependent. In univariate analysis female gender (odds ratio [OR] = 2.49, 95% CI: 1.1-5.5, P = 0.025), disease severity (OR = 2.43, 95% CI: 1.10-5.38, P = 0.029), and complicated disease (OR = 2.75, 95% CI: 1.18-6.41, P = 0.019) were associated with resistance. In multivariate analysis lower age at diagnosis (OR = 1.34,95% CI: 1.03-3.01, P = 0.040), coexisting upper digestive tract involvement (OR = 1.35, 95% CI: 1.06-3.07, P = 0.031), and concomitant immunomodulator use (OR = 0.35, 95% CI: 0.16-0.75, P = 0.007) were significantly associated with steroid dependency. CONCLUSIONS: Our results demonstrate that steroid dependency is a frequent complication in children with CD. Children with an earlier age at diagnosis and coexisting upper digestive tract involvement could be potentially targeted for steroid-sparing therapy.

Genes involved in the metabolism of poly-unsaturated fatty-acids (PUFA) and risk for Crohn's disease in children & young adults.

BACKGROUND AND OBJECTIVES: Epidemiological evidence for the role of polyunsaturated fatty-acids (PUFA) in Crohn's disease (CD) is unclear, although the key metabolite leucotriene B4 (LTB(4)) is closely linked to the inflammatory process. We hypothesized that inherited variation in key PUFA metabolic enzymes may modify susceptibility for CD. METHODS AND PRINCIPAL RESULTS: A case-control design was implemented at three pediatric gastroenterology clinics in Canada. Children ≤20 yrs diagnosed with CD and controls were recruited. 19 single nucleotide polymorphisms (SNPs) across the ALOX5 (4) CYP4F3 (5) and CYP4F2 (10) genes, were genotyped. Associations between SNPs/haplotypes and CD were examined. A total of 431 cases and 507 controls were studied. The mean (±SD) age of the cases was 12.4 (±3.3) years. Most cases were male (56.4%), had ileo-colonic disease (L3±L4, 52.7%) and inflammatory behavior (B1±p, 87%) at diagnosis. One genotyped CYP4F3 SNP (rs2683037) not in Hardy-Weinberg Equilibrium was excluded. No associations with the remaining 4 CYP4F3 SNPs with CD were evident. However haplotype analysis revealed associations with a two-marker haplotype (TG) (rs3794987 & rs1290617) (p = 0.02; permuted p = 0.08). CYP4F2 SNPs, rs3093158 (OR (recessive) = 0.56, 95% CI = 0.35-0.89; p = 0.01), rs2074902 (OR (trend) = 1.26, 95% CI = 1.00-1.60; p = 0.05), and rs2108622 (OR (recessive) = 1.6, 95% CI = 1.00-2.57; p = 0.05) were significantly associated whereas rs1272 (OR (recessive) = 0.58, 95% CI = 0.30-1.13; p = 0.10) showed suggestions for associations with CD. A haplotype comprising these 4 SNPs was significantly associated (p = 0.007, permuted p = 0.02) with CD. Associations with SNP rs3780901 in the ALOX5 gene were borderline non-significant (OR (dominant) = 1.29, 95% CI = 0.99-1.67; p = 0.056). A haplotype comprising the 4 ALOX5 SNPs (TCAA, p = 0.036) was associated with CD, but did not withstand corrections for multiple comparisons (permuted p = 0.14). CONCLUSIONS: Inherited variation in enzymes involved in the synthesis/metabolism of LTB(4) may be associated with CD. These findings implicate PUFA metabolism as a important pathway in the CD pathogenesis.

Association between genome-wide association studies reported SNPs and pediatric-onset Crohn's disease in Canadian children.

A recent pediatric-focused genome-wide association study has implicated three novel susceptibility loci for Crohn' disease (CD).We aimed to investigate whether the three recently reported and other previously reported genes/loci were also associated with CD in Canadian children. A case-control design was implemented at three pediatric gastroenterology clinics in Canada. Children <19 years of age with a confirmed diagnosis of CD were recruited along with controls. Single nucleotide polymorphisms (SNPs) in 19 reported genes/loci were genotyped. Associations between individual SNPs and CD were examined. A total of 563 cases and 553 controls were studied. The mean (+/-SD) age of the cases was 12.3 (+/-3.2) years. Most cases were male (56.0%), had ileo-colonic disease (L3 +/- L4, 48.8%) and inflammatory behavior (B1 +/- p, 87.9%) at diagnosis. Allelic association analysis (two-tailed) showed that 8 of the 19 targeted SNPs were significantly associated with overall susceptibility for CD. Associations with one additional SNP was borderline non-significant. Significantly associated SNPs included SNPs rs1250550 (p = 0.026) and rs8049439 (p = 0.04), recently reported to be specifically associated with pediatric-onset CD.Based on the results, we confirmed associations between two of the three novel pediatric-CD loci and other regions reported for associations with either pediatric and/or adult-onset CD.

Investigation of reported associations between the 20q13 and 21q22 loci and pediatric-onset Crohn's disease in Canadian children.

OBJECTIVES: A recent pediatric-focused genome-wide association study has reported novel associations of the 20q13 and 21q22 loci with inflammatory bowel disease (IBD). We aimed to investigate these associations with Crohn's disease (CD) in Canadian children. METHODS: A combined case-control and case-parent design was implemented at three pediatric gastroenterology clinics in Canada. Children less than 20 years of age with a confirmed diagnosis of CD were recruited along with controls. For a subset of the patients, biological parents were also recruited. Three single-nucleotide polymorphisms (SNPs) at the 20q13 locus and 1 SNP at the 21q22 locus were genotyped. Associations between individual SNPs and haplotypes were examined. RESULTS: A total of 410 cases, 415 controls, and 302 parents were studied. The mean (+/-s.d.) age for the cases was 12.3 (+/-3.2) years. Most cases were men (56.1%) who had ileocolonic disease (L3+/-L4, 52.2%) and inflammatory behavior (B1+/-B4, 87.0%) at diagnosis. Single SNP analysis showed that all 3 SNPs at the 20q13 locus were significantly associated with CD (rs2297441, P=2.24x10(-4); rs2315008, P=4.77x10(-4); rs4809330, P=6.08x10(-3)). Haplotype analysis suggested that the association signal at 20q13 resided on a common haplotype comprising the minor allele of rs2297441 (P=2.8x10(-5)). SNP rs2836878 at the 21q22 locus showed a trend for association with CD that was statistically not significant (P=0.06). CONCLUSIONS: Our results support an association between the 20q13 locus and CD in Canadian children. Positional cloning studies are required to further dissect the potential causative genes in the region.

Associations between ABCB1/MDR1 gene polymorphisms and Crohn's disease: a gene-wide study in a pediatric population.

BACKGROUND: Functional studies support the involvement of the MDR1 gene in the pathways leading to Crohn's disease (CD). Two common single nucleotide polymorphisms (SNPs), C3435T and G2677T/A, thought to alter the function of the corresponding P-glycoprotein, have shown inconsistent associations with CD. We investigated whether DNA variants in the MDR1 gene were associated with susceptibility for CD and specific phenotypes in children. METHODS: A case-control study was conducted at 3 gastroenterology clinics across Canada. Children with CD and population- or hospital-based controls were included. CD cases were classified using the Montreal Classification. Thirteen tag-SNPs and the C3435T variant in the MDR1 gene were genotyped. Single-SNP allelic, genotype as well as gene-wide haplotype associations with CD and its phenotypes at diagnosis were assessed. RESULTS: A total of 270 CD cases and 336 controls were studied. Most cases were male (56.3%), had disease location L3+/-L4 (58.1%), and an inflammatory phenotype B1+/-p (88.5%). Allelic association analysis revealed that SNP rs17327442 was significantly associated with overall susceptibility to CD (odds ratio [OR] = 0.72, 95% confidence interval [CI] = 0.50-0.99, P = 0.04) but this association did not withstand corrections for multiple testing (q-value = 0.56). Genotype-phenotype analysis indicated that 2 SNPs (rs10248420, P = 0.007, q-value = 0.07; rs2032583, P = 0.01, q-value = 0.07) were significantly associated with colonic disease. Five SNPs, rs1128503 (P = 0.02), rs1202184 (P = 0.008), rs1202186 (P = 0.02), rs2091766 (P = 0.03), and rs2235046 (P = 0.03) were nominally associated with noninflammatory CD. Specific haplotypes comprising of the tag-SNPs were significantly associated with either colonic or noninflammatory CD. CONCLUSIONS: Our comprehensive gene-wide analysis suggests that the MDR1 gene may be associated with clinical phenotypes of CD in children.

Autophagy gene ATG16L1 but not IRGM is associated with Crohn's disease in Canadian children.

BACKGROUND: Recent genome-wide studies have implicated the autophagy genes ATG16L1 and IRGM in the pathogenesis of Crohn's disease (CD). We investigated whether these genes were associated with CD in Canadian children. METHODS: A case-control study was carried out at 2 pediatric gastroenterology clinics in Canada. Confirmed cases of CD <20 years diagnosed using standard criteria were classified according to the Montreal Classification scheme. Single nucleotide polymorphisms (SNPs) rs2241880 (ATG16L1) and rs10065172 (IRGM) along with CARD15 SNPs, SNP8, SNP12, and SNP13 were genotyped. RESULTS: A total of 289 CD cases and 290 controls were studied. The mean age (+/-SD) of the cases was 12.1 (+/-3.5) years of age. Most cases were male (55.4%), had disease location L3 +/- L4 (56.7%), and an inflammatory phenotype B1 +/- p (87.2%) at diagnosis. rs2241880 (ATG16L1) was strongly associated with CD (allelic P = 1.24 x 10(-6)). Children with GG genotype had a more than 3-fold elevated risk for disease as compared to the wildtype AA homozygotes (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.93-4.94; P = 1.8 x 10(-6)). Association with SNP rs2241880 was specific for ileal disease (with or without colonic involvement) (case-based allelic P = 0.02; P-value versus controls = 9.5 x 10(-8)). The frequency of IRGM SNP rs10065172 was higher in cases but differences with controls were not statistically significant. No interactions between CARD15 and either ATG16L1 or IRGM were evident. CONCLUSIONS: We have confirmed associations between CD and ATG16L1 in a pediatric cohort of Canadian children. Associations with IRGM need to be further evaluated in larger studies.

Investigation of associations between the pregnane-X receptor gene (NR1I2) and Crohn's disease in Canadian children using a gene-wide haplotype-based approach.

BACKGROUND: The pregnane-X-receptor (PXR) is involved in the metabolism and detoxification of numerous xenobiotics and is critical for maintaining intestinal integrity. The NR1I2 gene encoding PXR may confer susceptibility for Crohn's disease (CD) but evidence for associations is conflicting. We investigated whether the NR1I2 gene was associated with susceptibility for pediatric CD. METHODS: A case-control and family-based (case-parent) study was carried out at 3 inflammatory bowel disease (IBD) clinics across Canada. Confirmed cases of CD <20 years were diagnosed using standard criteria. For determination of gene associations parents of the cases and unrelated controls were evaluated. Clinical phenotypes were established based on the Montreal Classification scheme. Eight tag-SNPs (tag-single nucleotide polymorphisms) across the gene were genotyped for allelic or genotypic associations. RESULTS: A total of 270 CD cases, 336 controls, and 395 parents were studied. The mean age (+/-SD) of the cases was 12.1 (+/-3.5) years of age. Most cases were male (56.3%), had disease location L3+/-L4 (58.1%), and an inflammatory phenotype B1+/-p (88.4%) at diagnosis. For 7 SNPs single SNP analysis using case-control or case-parent data did not reveal associations with development of CD and none of the SNPs were significantly associated with disease location or disease behavior at diagnosis. One SNP rs2461823 (P = 0.05) was nominally associated with CD. No overall haplotype association (omnibus P-value = 0.61) or associations with individual haplotypes was evident. CONCLUSIONS: Our gene-wide analysis in a pediatric cohort using both the case-control and case-parent designs suggests that the NR1I2 gene is not associated with CD in Canadian children.

Association between genetic variants in the IL-23R gene and early-onset Crohn's disease: results from a case-control and family-based study among Canadian children.

BACKGROUND AND OBJECTIVES: Interleukin (IL)-23 is a key regulator of inflammation and influences the activities of T-helper 17 (Th-17) lymphocytes. Recent reports indicate that variants in the gene coding for its receptor (IL-23R) are strongly associated with Crohn's disease (CD). We investigated whether DNA variants in the IL-23R gene determine susceptibility for CD in Canadian children. DESIGN AND METHODS: A case-control and case-parent trio design was implemented at three pediatric centers across Canada. Cases of CD (

Investigating the hygiene hypothesis as a risk factor in pediatric onset Crohn's disease: a case-control study.

BACKGROUND AND OBJECTIVES: Evidence for the hygiene hypothesis in the etiology of Crohn's disease (CD) is unclear. We investigated the relationship between infection-related exposures and risk for CD in children. METHODS: A hospital-based case-control was carried out. Newly-diagnosed cases of CD (n = 194), less than 20 yr of age were recruited from the gastroenterology clinic of a large-pediatric inflammatory bowel disease (IBD) center in Montreal, Canada. Orthopedic patients pair-matched (n = 194) for timing of diagnosis and area of residence were recruited as controls. Information on infection-related exposures between birth and disease diagnosis was ascertained by administering a structured questionnaire to the mother and the index subject. The relationship between the frequency and timing of infection-related exposures with CD was studied. RESULTS: The mean age (SD) at diagnosis was 12.3 (5.1). CD was more common after 10 yr of age. Gender distribution was similar between comparison groups. In multivariate conditional logistic regression, family history of IBD (odds ratio (OR) = 4.6; 95% confidence interval (CI) = 1.6-13.3), age (OR = 1.2; 95% CI = 1.1-1.3), and owning a pet (OR = 2.0; 95% CI = 0.9-4.5) were associated with risk for CD, whereas regular use of a personal towel (OR = 0.5; 95% CI = 0.2-0.9) and lesser crowding in homes (OR = 0.3; 95% CI = 0.1-0.8) were protective. Day-care attendance during the first 6 months of life and "physician-diagnosed infections" between 5 and 10 yr of age were associated with increased risks for CD. CONCLUSIONS: Infection-related exposures seem to enhance risk for CD in children. The timing of these exposures during early childhood may be relevant to the etiology of pediatric CD.