Guy Grimard

Imbalances in Dietary Consumption of Fatty Acids, Vegetables, and Fruits Are Associated With Risk for Crohn's Disease in Children

BACKGROUND AND OBJECTIVES:The role of dietary factors in the etiology of Crohns disease (CD) is inconsistent largely due to difficulties in acquiring valid information on consumption habits. We examined the impact of diet on new onset CD in children using a validated food-frequency questionnaire (FFQ).METHODOLOGY:A case-control study was carried out. Children ≤20 yr, newly diagnosed with CD, were recruited from 3 pediatric gastroenterology clinics across Canada. Population or hospital controls were selected matched to cases for time of diagnosis (±6 months) and area of residence. Dietary consumption 1 yr prior to disease diagnosis was evaluated using a validated FFQ, administered within 1 month of diagnosis. Conditional logistic regression analysis adjusting for potential confounding variables (energy intake, age, gender, body mass index) was carried out.RESULTS: A total of 130 CD patients and 202 controls were studied. Mean age at diagnosis (±SD) was 14.2 (2.7). There were more male patients (59%). Comparing the highest to the lowest levels of consumption, higher amounts of vegetables (OR 0.69, 95% CI 0.33–1.44, P = 0.03), fruits (OR 0.49, 95% CI 0.25–0.96, P = 0.02), fish (OR 0.46, 95% CI 0.20–1.06, P = 0.02), and dietary fiber (OR 0.12, 95% CI 0.04–0.37, P < 0.001) protected from CD. Consumption of long-chain omega-3 fatty acids (LCN-ω-3) was negatively associated with CD (OR 0.44, 95% CI 0.19–1.00, P < 0.001). A higher ratio of LCN-ω-3/ω-6 fatty acids was significantly associated with lower risks for CD (OR 0.32, 95% CI 0.14–0.71, P = 0.02).CONCLUSIONS: Our findings indicate that an imbalance in consumption of fatty acids, vegetables, and fruits is associated with increased risks for CD among Canadian children.

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 Crohns 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.

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 Crohns 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 (≤20 yr) along with their parents and controls were recruited. DNA samples were collected and genotyped for 10 single nucleotide polymorphisms (SNPs) in the IL-23R gene and three common SNPs in the CARD15 gene. Transmission disequilibrium-based tests were applied to the case-parent data and logistic regression models to the case-control data to study the association between the SNPs and CD.RESULTS:A total of 259 CD cases, 139 controls, and 232 families (167 trios and 65 dyads) were studied. The mean age at diagnosis was 13.3 yr (range 2.6–20 yr). The majority of the patients were Caucasian. Case-control analysis revealed significant associations with three SNPs (rs1004819, rs7517847, and rs11209026 [R381Q]) and borderline nonsignificant associations with three other SNPs (rs10489629, rs10889697, and rs11465804) in the IL-23R gene. Having any CARD15 variant was associated with a significant risk for CD (P < 0.0001). Analyses of case-parent data confirmed the findings from the case-control analysis including significant associations with the R381Q SNP (P = 0.002). The common variant in this SNP conferred risk for CD. These associations were largely independent of the CARD15 gene.CONCLUSIONS:Our findings confirm recently reported genome-wide associations between the IL-23R gene and CD. They suggest that the gene is also associated with pediatric-onset CD among Canadian 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 Crohns 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 × 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 × 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 × 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. (Inflamm Bowel Dis 2008)

Interleukin 10 (IL‐10) gene variants and susceptibility for paediatric onset Crohn’s disease

Backgroundu2002 A recent genome‐wide association study in adult patients with ulcerative colitis (UC) has implicated the interleukin 10 (IL‐10) gene as an important candidate gene. Moreover, a UC‐associated single nucleotide polymorphism (SNP) rs3024405 was also significantly associated with adult Crohn’s disease (CD).

Susceptibility loci reported in genome‐wide association studies are associated with Crohn’s disease in Canadian children

Aliment Pharmacol Theru200231, 1186–1191

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 Crohns 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=2.24×10−4; rs2315008, P=4.77×10−4; rs4809330, P=6.08×10−3). Haplotype analysis suggested that the association signal at 20q13 resided on a common haplotype comprising the minor allele of rs2297441 (P=2.8×10−5). 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 Crohns 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.

Prospective validation and head-to-head comparison of 3 ankle rules in a pediatric population.

STUDY OBJECTIVEnThe Ottawa Ankle Rules, Low-Risk Exam, and Malleolar Zone Algorithm are assessment rules designed to minimize radiographs performed on children with ankle trauma. We aim to determine the criterion validity of the abovementioned 3 rules for predicting clinically important ankle fractures in children.nnnMETHODSnThis was a prospective cohort study performed in a pediatric emergency department. Children aged 16 years and younger and with acute ankle trauma were eligible. Physicians were initially trained to assess patients according to the Ottawa Ankle Rules, Low-Risk Exam, and Malleolar Zone Algorithm. Furthermore, they implemented each rule with a standardized diagram. Radiography and referral to orthopedics were left to the physicians discretion. The primary outcome was the confirmation of a clinically important fracture confirmed during the orthopedic follow-up. Patients who did not require orthopedic follow-up were contacted by telephone.nnnRESULTSnRadiography was performed for 245 of the 272 participants. All patients with no radiograph were reached by telephone. Forty-seven participants had a clinically important fracture. The sensitivity and specificity of the rules were 1.00 (95% confidence interval [CI] 0.93 to 1.00) and 0.27 (95% CI 0.21 to 0.33) for the Ottawa Ankle Rules, 0.87 (95% CI 0.75 to 0.94) and 0.54 (95% CI 0.47 to 0.60) for the Low-Risk Exam, and 0.94 (95% CI 0.83 to 0.98) and 0.24 (95% CI 0.19 to 0.31) for the Malleolar Zone Algorithm.nnnCONCLUSIONnThe Ottawa Ankle Rules identified all children with a clinically important fracture, whereas the Low-Risk Exam and the Malleolar Zone Algorithm showed lower sensitivities. The Low-Risk Exam showed the best specificity for clinically important fractures, decreasing the need for radiograph by 49%, but had missed 6 important fractures.

A Non-Synonymous Coding Variant (L616F) in the TLR5 Gene Is Potentially Associated with Crohn's Disease and Influences Responses to Bacterial Flagellin

Background and Objectives Although numerous studies have implicated TLR5, or its ligands, bacterial flagellins, in the pathogenesis of Crohns disease (CD), genome-wide association studies (GWAS) have not reported associations with the TLR5 gene. We aimed to examine potential CD-associated TLR5 variants and assess whether they modified inflammatory responses to bacterial flagellins. Methods and Principal Results A two-stage study was carried out. In stage 1, we genotyped tagging single-nucleotide polymorphisms (tag-SNPs) in the TLR5 gene in a sample of CD cases (<20 years of age, Nu200a=u200a566) and controls (Nu200a=u200a536). Single SNP and haplotype analysis was carried out. In Stage 2, we assessed the functional significance of potential CD-associated variant(s) vis-à-vis effects on the inflammatory response to bacterial flagellin using HEK293T cells. We observed marginal association between a non-synonymous coding SNP rs5744174 (pu200a=u200a0.05) and CD. Associations between SNP rs851139 that is in high linkage disequilibrium (LD) with SNP rs5744174 were also suggested (pu200a=u200a0.07). Haplotype analysis revealed that a 3 marker haplotype was significantly associated with CD (pu200a=u200a0.01). Functional studies showed that the risk allele (616F) (corresponding to the C allele of SNP rs5744174) conferred significantly greater production of CCL20 in response to a range of flagellin doses than the comparator allele (616L). Conclusions Our findings suggest that a non-synonymous coding variation in the TLR5 gene may confer modest susceptibility for CD.