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Objective Generic preference-based HRQOL assessments used expressly for economic evaluation have not been examined in pediatric Crohn’s disease (CD) and ulcerative colitis (UC). The objective was to further assess the construct validity of preference-based HRQOL measures in pediatric IBD by comparing the Child Health Utility 9 Dimensions (CHU9D) and Health Utilities Index (HUI) to the disease-specific IMPACT-III and to the generic PedsQL in children with CD and with UC. Methods The CHU9D, HUI, IMPACT-III and/or PedsQL were administered to Canadian children aged 6 to 18 years with CD and UC. CHU9D total and domain utilities were calculated using adult and youth tariffs. HUI total and attribute utilities were determined for the HUI2 and HUI3. Total scores for IMPACT-III and PedsQL were determined. Spearman correlations were calculated between generic preference-based utilities and the IMPACT-III and PedsQL scores. Results The questionnaires were administered to 157 children with CD and 73 children with UC. Moderate to strong correlations were observed between the CHU9D, HUI2, HUI3 and the disease-specific IMPACT-III or generic PedsQL. As hypothesized, domains with similar constructs demonstrated stronger correlations, such as the Pain and Well-being domains. Conclusions While all questionnaires were moderately correlated with the IMPACT-III and PedsQL questionnaires, the CHU9D using youth tariffs and the HUI3 were most strongly correlated and would be suitable choices to generate health utilities for children with CD or UC for the purpose of economic evaluation of treatments in pediatric IBD.

Background and AimsWe aimed to determine whether a targeted gene expression panel could predict clinical outcomes in paediatric ulcerative colitis [UC] and investigated putative pathogenic roles of predictive genes.MethodsIn total, 313 rectal RNA samples from a cohort of newly diagnosed paediatric UC patients (PROTECT) were analysed by a real-time PCR microfluidic array for expression of type 1, 2 and 17 inflammation genes. Associations between expression and clinical outcomes were assessed by logistic regression. Identified prognostic markers were further analysed using existing RNA sequencing (RNA-seq) data sets and tissue immunostaining.ResultsIL13RA2 was associated with a lower likelihood of corticosteroid-free remission (CSFR) on mesalamine at week 52 (p = .002). A model including IL13RA2 and only baseline clinical parameters was as accurate as an established clinical model, which requires week 4 remission status. RORC was associated with a lower likelihood of colectomy by week 52. A model including RORC and PUCAI predicted colectomy by 52 weeks (area under the receiver operating characteristic curve 0.71). Bulk RNA-seq identified IL13RA2 and RORC as hub genes within UC outcome-associated expression networks related to extracellular matrix and innate immune response, and lipid metabolism and microvillus assembly, respectively. Adult UC single-cell RNA-seq data revealed IL13RA2 and RORC co-expressed genes were localized to inflammatory fibroblasts and undifferentiated epithelial cells, respectively, which was supported by protein immunostaining.ConclusionTargeted assessment of rectal mucosal immune gene expression predicts 52-week CSFR in treatment-naïve paediatric UC patients. Further exploration of IL-13Rɑ2 as a therapeutic target in UC and future studies of the epithelial-specific role of RORC in UC pathogenesis are warranted.

Purpose Health utilities are challenging to ascertain in children and have not been studied in pediatric Crohn’s disease (CD) and ulcerative colitis (UC). The objective was to assess discriminative validity by comparing utilities elicited using the Child Health Utility-9 Dimension (CHU9D) to the Health Utilities Index (HUI) across multiple disease activity scales in pediatric UC and CD. Methods Preference-based instruments were administered to 188 children with CD and 83 children with UC aged 6 to 18 years. Utilities were calculated using CHU9D adult and youth tariffs, and HUI2 and HUI3 algorithms in children with inactive (quiescent) and active (mild, moderate, and severe) disease. Differences between instruments, tariff sets and disease activity categories and were tested statistically. Results In CD and UC, all instruments detected significantly higher utilities for inactive compared to active disease (p Conclusion CHU9D and HUI discriminated between levels of disease activity in CD and UC regardless of the clinical scale used, with the CHU9D youth tariff most often displaying the lowest utilities for worse health states. Distinct utilities for different IBD disease activity states can be used in health state transition models evaluating the cost-effectiveness of treatments for pediatric CD and UC.

Summary An important goal of clinical genomics is to be able to estimate the risk of adverse disease outcomes. Between 5% and 10% of individuals with ulcerative colitis (UC) require colectomy within 5 years of diagnosis, but polygenic risk scores (PRSs) utilizing findings from genome-wide association studies (GWASs) are unable to provide meaningful prediction of this adverse status. By contrast, in Crohn disease, gene expression profiling of GWAS-significant genes does provide some stratification of risk of progression to complicated disease in the form of a transcriptional risk score (TRS). Here, we demonstrate that a measured TRS based on bulk rectal gene expression in the PROTECT inception cohort study has a positive predictive value approaching 50% for colectomy. Single-cell profiling demonstrates that the genes are active in multiple diverse cell types from both the epithelial and immune compartments. Expression quantitative trait locus (QTL) analysis identifies genes with differential effects at baseline and week 52 follow-up, but for the most part, differential expression associated with colectomy risk is independent of local genetic regulation. Nevertheless, a predicted polygenic transcriptional risk score (PPTRS) derived by summation of transcriptome-wide association study (TWAS) effects identifies UC-affected individuals at 5-fold elevated risk of colectomy with data from the UK Biobank population cohort studies, independently replicated in an NIDDK-IBDGC dataset. Prediction of gene expression from relatively small transcriptome datasets can thus be used in conjunction with TWASs for stratification of risk of disease complications.

While fecal calprotectin (FC) is used to assess disease activity in ulcerative colitis (UC) there are little data concerning the role of serial FC levels at diagnosis in predicting clinical course. We sought to determine whether FC at diagnosis or early change following therapy predicts clinical outcomes in pediatric UC.Methods: Children with newly diagnosed UC were treated with standardized regimens of mesalamine or corticosteroids (CS). CS tapering and escalation to additional therapy or colectomy were by protocol. Patients with baseline or week 4 or week 12 FC levels were included in the analysis. Our primary outcome was CS-free remission on mesalamine at week 52. We compared the prognostic value of a baseline FC as well as a change in FC by week 4 or week 12 in predicting clinical outcomes.The study included 352 children (113 initial mesalamine, 239 initial CS, mean age 12.6 years) with UC. At Week 52, 135 (38.3%), 84 (23.8%), and 19 (5.4%) children achieved CS-free remission, needed anti-tumor necrosis factor therapy or had colectomy respectively. Baseline FC was not associated with CS-free remission at week 52. However, both week 4 (odds ratio [OR] 0.95, 95% confidence interval [CI] 0.901.00) and week 12 FC levels (OR 0.91, 95% CI 0.87-0.96) were associated with outcomes, with the latter having a stronger association with CS-free remission. Patients with a75% decrease by 12 weeks, had a 3-fold increased likelihood of CS-free remission at 1 year.Longitudinal changes in FC may predict 1 year outcomes better than values at diagnosis in children with a new diagnosis of UC.

BACKGROUND The phase 3 (UNIFI) trial of ustekinumab (anti-interleukin 12/23) demonstrated efficacy even after prior biologic failure in adult ulcerative colitis (UC), but paediatric data are lacking. AIM To prospectively monitor efficacy and serum concentrations of ustekinumab given to children with UC refractory to other biologics. METHODS Children with anti-TNF refractory UC initiating ustekinumab intravenously at sites of the Canadian Children IBD Network prior to 12/2019 are included. The primary endpoint was steroid-free clinical remission with subcutaneous ustekinumab at 52 weeks (Paediatric Ulcerative Colitis Activity Index

Background Develop a clinical and biological predictive model for colectomy risk in children newly diagnosed with ulcerative colitis (UC). Methods This was a multicenter inception cohort study of children (ages 4-17 years) newly diagnosed with UC treated with standardized initial regimens of mesalamine or corticosteroids (CS) depending upon initial disease severity. Therapy escalation to immunomodulators or infliximab was based on predetermined criteria. Patients were phenotyped by clinical activity per the Pediatric Ulcerative Colitis Activity Index (PUCAI), disease extent, endoscopic/histologic severity, and laboratory markers. In addition, RNA sequencing defined pretreatment rectal gene expression and high density DNA genotyping by the Affymetrix UK Biobank Axiom Array. Coprimary outcomes were colectomy over 3 years and time to colectomy. Generalized linear models, Cox proportional hazards multivariate regression modeling, and Kaplan-Meier plots were used. Results Four hundred twenty-eight patients (mean age 13 years) started initial theapy with mesalamine (n = 136), oral CS (n = 144), or intravenous CS (n = 148). Twenty-five (6%) underwent colectomy at ≤1 year, 33 (9%) at ≤2 years, and 35 (13%) at ≤3 years. Further, 32/35 patients who had colectomy failed infliximab. An initial PUCAI ≥ 65 was highly associated with colectomy (P = 0.0001). A logistic regression model predicting colectomy using the PUCAI, hemoglobin, and erythrocyte sedimentation rate had a receiver operating characteristic area under the curve of 0.78 (95% confidence interval [0.73, 0.84]). Addition of a pretreatment rectal gene expression panel reflecting activation of the innate immune system and response to external stimuli and bacteria to the clinical model improved the receiver operating characteristic area under the curve to 0.87 (95% confidence interval [0.82, 0.91]). Conclusions A small group of children newly diagnosed with severe UC still require colectomy despite current therapies. Our gene signature observations suggest additional targets for management of those patients not responding to current medical therapies.

Background & Aims Altered gut microbiota composition and function have been associated with inflammatory bowel diseases, including ulcerative colitis (UC), but the causality and mechanisms remain unknown. Methods We applied 16S ribosomal RNA gene sequencing, shotgun metagenomic sequencing, in vitro functional assays, and gnotobiotic colonizations to define the microbial composition and function in fecal samples obtained from a cohort of healthy individuals at risk for inflammatory bowel diseases (pre-UC) who later developed UC (post-UC) and matched healthy control individuals (HCs). Results Microbiota composition of post-UC samples was different from HC and pre-UC samples; however, functional analysis showed increased fecal proteolytic and elastase activity before UC onset. Metagenomics identified more than 22,000 gene families that were significantly different between HC, pre-UC, and post-UC samples. Of these, 237 related to proteases and peptidases, suggesting a bacterial component to the pre-UC proteolytic signature. Elastase activity inversely correlated with the relative abundance of Adlercreutzia and other potentially beneficial taxa and directly correlated with known proteolytic taxa, such as Bacteroides vulgatus. High elastase activity was confirmed in Bacteroides isolates from fecal samples. The bacterial contribution and functional significance of the proteolytic signature were investigated in germ-free adult mice and in dams colonized with HC, pre-UC, or post-UC microbiota. Mice colonized with or born from pre-UC–colonized dams developed higher fecal proteolytic activity and an inflammatory immune tone compared with HC-colonized mice. Conclusions We have identified increased fecal proteolytic activity that precedes the clinical diagnosis of UC and associates with gut microbiota changes. This proteolytic signature may constitute a noninvasive biomarker of inflammation to monitor at-risk populations that can be targeted therapeutically with antiproteases.

CARMIL2 is required for CD28-mediated co-stimulation of NF-κB signaling in T cells and its deficiency has been associated with primary immunodeficiency and, recently, very early onset inflammatory bowel disease (IBD). Here we describe the identification of novel biallelic CARMIL2 variants in three patients presenting with pediatric-onset IBD and in one with autoimmune polyendocrine syndrome (APS). None manifested overt clinical signs of immunodeficiency before their diagnosis. The first patient presented with very early onset IBD. His brother was found homozygous for the same CARMIL2 null variant and diagnosed with APS. Two other IBD patients were found homozygous for a nonsense and a missense CARMIL2 variant, respectively, and they both experienced a complicated postoperative course marked by severe infections. Immunostaining of bowel biopsies showed reduced CARMIL2 expression in all the three patients with IBD. Western blot and immunofluorescence of transfected cells revealed an altered expression pattern of the missense variant. Our work expands the genotypic and phenotypic spectrum of CARMIL2 deficiency, which can present with either IBD or APS, aside from classic immunodeficiency manifestations. CARMIL2 should be included in the diagnostic work-up of patients with suspected monogenic IBD.

Data on pediatric inflammatory bowel disease (IBD)-associated indirect and out-of-pocket (OOP) costs are limited. We aimed to estimate indirect (lost work hours and productivity) and OOP pediatric IBD-associated costs in Canada.In a nation-wide cross-sectional analysis, caregivers of children with IBD were invited to complete a questionnaire on lost work hours and OOP costs related to IBD in the 4 weeks prior to the survey. Participants were reinvited to periodically answer the same questionnaire every 3-9 months for 2 years. Lost productivity was calculated using the Human Capital method. Costs were reported in 2018 inflation-adjusted Canadian dollars. Predictors of high cost users (top 25%) were examined using binary logistic regression.Consecutive 243 (82 incident cases) of 262 (92.7%) approached participants completed the first survey with a total of 450 surveys longitudinally completed over 2 years. The median annual indirect cost per patient was $5966 (IQR $1809-$12,676), with $5721 (IQR $1366-$11,545) for Crohn's disease (CD) and $7007 (IQR $2428-$14,057) for ulcerative colitis (UC) ( P = 0.11). The annual median per patient OOP costs were $4550 with $4550 for CD and $5038 for UC ( P = 0.53). Longer travel distance to clinic was associated with higher OOP costs (odds ratio = 4.55; Plt; 0.0001; 95% confidence interval: 1.99-10.40).Indirect and OOP IBD-associated costs are substantial and more likely to affect families living in remote communities.

Background Data on the association between early postinduction serum adalimumab (ADA) trough levels (TLs) and objective outcomes are scarce. The aim of this study was to investigate whether early ADA TLs at weeks 4 and 8 are associated with clinical and biomarker remission at week 24 in pediatric Crohn’s disease (CD). Methods Adalimumab TLs at weeks 4 and 8 were prospectively measured in anti-TNF-naïve children initiating treatment with ADA monotherapy for luminal inflammatory CD. The primary outcome was combined clinical and biomarker remission at week 24, defined as achieving steroid-free clinical remission (Pediatric CD activity index Results Among 65 patients, 39 (60%) achieved combined clinical/biomarker remission at week 24 without dose escalation. Adalimumab TLs at both weeks 4 and 8 were significantly higher in remitters vs nonremitters at week 24 (P Conclusion Greater early ADA exposure is associated with superior clinical/biomarker outcomes at week 24.

Background & Aims: A proportion of infants and young children with inflammatory bowel diseases (IBDs) have subtypes associated with a single gene variant (monogenic IBD). We aimed to determine the prevalence of monogenic disease in a cohort of pediatric patients with IBD. Methods: We performed whole-exome sequencing analyses of blood samples from an unselected cohort of 1005 children with IBD, aged 0–18 years (median age at diagnosis, 11.96 years) at a single center in Canada and their family members (2305 samples total). Variants believed to cause IBD were validated using Sanger sequencing. Biopsies from patients were analyzed by immunofluorescence and histochemical analyses. Results: We identified 40 rare variants associated with 21 monogenic genes among 31 of the 1005 children with IBD (including 5 variants in XIAP, 3 in DOCK8, and 2 each in FOXP3, GUCY2C, and LRBA). These variants occurred in 7.8% of children younger than 6 years and 2.3% of children aged 6–18 years. Of the 17 patients with monogenic Crohn’s disease, 35% had abdominal pain, 24% had nonbloody loose stool, 18% had vomiting, 18% had weight loss, and 5% had intermittent bloody loose stool. The 14 patients with monogenic ulcerative colitis or IBD-unclassified received their diagnosis at a younger age, and their most predominant feature was bloody loose stool (78%). Features associated with monogenic IBD, compared to cases of IBD not associated with a single variant, were age of onset younger than 2 years (odds ratio [OR], 6.30; P = .020), family history of autoimmune disease (OR, 5.12; P = .002), extra-intestinal manifestations (OR, 15.36; P < .0001), and surgery (OR, 3.42; P = .042). Seventeen patients had variants in genes that could be corrected with allogeneic hematopoietic stem cell transplantation. Conclusions: In whole-exome sequencing analyses of more than 1000 children with IBD at a single center, we found that 3% had rare variants in genes previously associated with pediatric IBD. These were associated with different IBD phenotypes, and 1% of the patients had variants that could be potentially corrected with allogeneic hematopoietic stem cell transplantation. Monogenic IBD is rare, but should be considered in analysis of all patients with pediatric onset of IBD.

Objective The aim of the study was to assess the body composition of children with inflammatory bowel disease (IBD) and to study the accuracy of clinically available tools in predicting excess body fatness. We aimed at also exploring the influence of adiposity on pharmacokinetics during early Infliximab exposure. Methods Prospective cohort study in 5- to 17-year-old children with IBD initiating Infliximab therapy. Patient demographic, phenotypic, and laboratory data at the time of Infliximab initiation were recorded. Body composition was assessed using air displacement plethysmography (ADP). fat mass index (FMI = fat mass [kg]/(height [m])) was calculated to determine excess adiposity (defined as FMI ≥75th centile). Anthropometrics (weight, height, mid upper arm circumference [MUAC] and triceps skin fold thickness [TSF]) were obtained and MUAC and TSF measurements were used to calculate arm fat area (AFA) and arm muscle area z-scores. Statistical analysis was applied as appropriate. Results Fifty-three (68% male; 55% Crohn disease [CD], 45% ulcerative colitis [UC], median [IQR] age 15 [13-16] years) children with IBD were included. Twenty-four percentage of children with IBD (21% CD, 29% UC) had excess adiposity. Four children (31%) with FMI ≥75th centile were not identified by body mass index (BMI) alone (kappa of 0.60), and 2 children (15%) were not identified by AFA z-score alone. The intra- and interobserver reliability of MUAC and TSFT measurements was excellent. There was no difference in Infliximab trough levels at the end of induction between those with FMI less than or ≥75th centile. Conclusions Excess adiposity affects approximately 1 in 4 young patients with IBD and can be missed by routine obesity screening. Our exploratory study did not raise concerns of underexposure to infliximab in those children with excess adiposity during early drug exposure.

Pediatric Crohn disease (CD) treatment goals have evolved. Among children receiving adalimumab (ADA) we examined long-term durability of clinical remission, linear growth, and associations of trough concentration (TC) with biomarker, endoscopic and imaging outcomes.Single-center retrospective study. Pediatric CD activity index, C-reactive protein, fecal calprotectin, and height measured longitudinally. Discontinuation due to secondary loss of response (LOR) was assessed using Cox proportional hazards model. Associations between TC and clinical and biomarker remission, endoscopic and magnetic resonance imaging (MRI) improvements were assessed using Cox regression with time-dependent covariates.Between January 2007 and June 2018, 213 children (median age 14.1 years (interquartile range [IQR] 12.5-15.7) 65% males) initiated ADA. One hundred and seventy-four (82%) achieved clinical remission (PCDAI10). During 24.8 (IQR 15.6-38.4) months follow-up, 26 (15%) discontinued ADA due to LOR, and 10 (6%) due to adverse events. Being anti-tumor necrosis factor (TNF) naïve and inflammatory behavior associated with increased likelihood of clinical remission (odds ratio [OR] 2.39, P = 0.033, and 3.13, P = 0.013, respectively) and with decreased LOR (hazard ratio [HR] 0.3, P = 0.002, and HR 0.35, P = 0.01, respectively). Cumulative LOR among 135 anti-TNF naïve patients: 0%, 8%, 15% within 1, 2, 3 years, similarly durable with mono- and immunomodulator combination therapy. Among pre-/early pubertal children mean height (-0.82) normalized to -0.07. TC consistently7.5 ug/mL was associated with durable clinical remission (HR = 17.24, P 0.001); TC10 ug/mL with durable biomarker remission (HR = 6.56, P 0.001) and endoscopic (OR 10.4, P = 0.002) and MRI (OR 7.6, P = 0.001) improvements.ADA monotherapy maintains durable clinical remission. Biomarker remission, mucosal and transmural improvements were associated with greater ADA exposure.

Background & aims: We aimed to model infliximab (IFX) pharmacokinetics (PK) in pediatric acute severe ulcerative colitis (ASUC) and assess the association between PK parameters, including drug exposure, and clinical response. Methods: We studied a multicenter prospective cohort of hospitalized children initiating IFX for ASUC or IBD-unclassified. Serial IFX serum concentrations over 26 weeks were used to develop a PK model. We tested the association of PK parameter estimates with day 7 clinical response, week 8 clinical remission, week 26 corticosteroid-free clinical remission (CSF-CR) (using the Pediatric Ulcerative Colitis Activity Index), and colectomy-free survival. Results: Thirty-eight participants received IFX (median initial dose, 9.9 mg/kg). Day 7 clinical response, week 8 clinical remission, and week 26 CSF-CR occurred in 71%, 55%, and 43%, respectively. Albumin, C-reactive protein, white blood cell count, platelets, weight, and antibodies to IFX were significant covariates incorporated into a PK model. Week 26 non-remitters exhibited faster IFX clearance than remitters (P =.013). However, cumulative IFX exposure did not differ between clinical response groups. One (2.7%) and 4 (10.8%) participants underwent colectomy by week 26 and 2 years, respectively. Day 3 IFX clearance >0.02 L/h was associated with colectomy (hazard ratio, 58.2; 95% confidence interval, 6.0–568.6; P

Cross-sectional imaging is important in the assessment of transmural inflammation in Crohn's disease (CD). Small bowel involvement is often more extensive in pediatric CD, requiring a panentering measuring tool. We undertook to develop a magnetic resonance enterography (MRE)-based index that would measure inflammation in all segments of the intestine, without rectal contrast.Children with CD underwent ileocolonoscopy and MRE and half were prospectively followed for 18 months when MRE was repeated. Item generation and reduction were performed by a Delphi panel of pediatric radiologists, a systematic literature review, a cross-sectional study of 48 MREs, and a steering committee. Formatting and weighting were performed using multivariate modeling adjusted by a steering committee. MREs were read locally and centrally. Reliability, validity, and responsiveness were determined using several clinimetric and psychometric approaches.Thirty items were initially generated and reduced to 5 using regression analysis on 159 MREs: wall thickness, wall diffusion weighted imaging, ulcerations, mesenteric edema, and comb sign. In the validation cohort of 81 MREs, the weighted global PICMI correlated well with the radiologist global assessment (r = 0.85; P.001) and with the simple endoscopic score in a subsample with ileocolonic disease (r = 0.63; P.001). Interobserver and test-retest reliability were high (interclass correlation coefficients, 0.84; 95% confidence interval [CI], 0.79-0.87; and 0.81, 95% CI, 0.65-0.90, respectively; both P.001). Excellent responsiveness was found at repeated visits (n = 116 MREs; area under the receiver operating characteristic curve 0.96; 95% CI, 0.93-0.99). Transmural healing was defined as PICMI ≤10 and response as a change of20 points with excellent discriminative validity (area under the receiver operating characteristic curve = 0.96; 95% CI, 0.93-0.99).The PICMI is a valid, reliable, and responsive index for assessing transmural inflammation in pediatric CD. It scores the entire bowel length and does not require intravenous contrast or rectal enema and, therefore, is suitable for use in children. (ClinicalTrials.gov, Number: NCT01881490.).

Background Canadian-born children of South Asian [SA] ethnicity develop inflammatory bowel disease [IBD] at similar rates to those among Caucasian children. We evaluated the variation in phenotypic spectrum of IBD in SA and Caucasian children in a national paediatric inception cohort of new-onset IBD. Methods Patients aged Results Of 1156 children enrolled over 2014 to 2019, 623 were Caucasian [98% and 88% parents Canadian born] and 114 SA [79% Canadian born, 87% parents SA born]. Fewer SAs have a first-degree relative with IBD, 6% vs 19% in Caucasians, p = 0.002. SAs present at a younger age, median age 11.4 years (interquartile range [IQR] 9.2–14.3) vs 13 years [IQR 10.9-15 years], p = 0.03 and more commonly with a UC/IBD-U [ulcerative colitis/IBD-unclassified] subtype [ratio of UC/IBD-U to CD 1.2:1 vs 1:1.8 for Caucasians, p Conclusions The phenotypic spectrum of new-onset IBD in SA children differs from that of Caucasian children, but treatment and clinical course are similar within phenotypic subgroups.

Although inflammatory bowel diseases (IBD) associated with primary sclerosing cholangitis (PSC) have been well characterized in adults, there have been few pediatric studies, and these were small and produced conflicting results. We investigated features of PSC-IBD in children, compared with children with IBD without PSC.We performed a retrospective study of 74 children with PSC-IBD, diagnosed from 2000 through 2018, who were each matched with 2 children with ulcerative colitis or IBD-unclassified (controls) based on sex, date of birth, and type of IBD. We compared IBD distribution and clinical activity (remission, medication use, hospitalization, or colectomy) and patient growth between groups. Data were extracted from each hospital contact and analyzed using mixed effects analyses or Cox proportional hazards regression, adjusting for time-dependent medication exposure.Higher proportions of children with PSC-IBD had backwash ileitis, pancolitis, and rectal sparing, and more severe right-sided disease, than controls (P.05). Patients with PSC-IBD were more likely to be treated with only 5-ASA, compared with controls (odds ratio [OR], 3.04; 95% CI, 1.44-6.41) and to have IBD in clinical remission (OR, 2.94; 95% CI, 1.78-4.87). Risk of colectomy or treatment with a biologic agent was lower in patients with PSC-IBD than controls (hazard ratio, 0.24; 95% CI, 0.12-0.52). However, determination of IBD severity based on symptoms underestimated severity based on endoscopic activity in patients with PSC-IBD. Among patients with IBD in clinical remission, those with PSC were less likely to have endoscopic remission (OR, 0.44; 95% CI, 0.20-0.96). Patients with PSC-IBD were shorter and had lower weight over time, compared with controls.In a retrospective study, we found that features of IBD differed between children with vs without PSC, similar to adults. Despite the mild clinical activity of IBD in patients with PSC, lack of symptoms does not always indicate lack of mucosal inflammation. Children with PSC-IBD have greater growth impairments compared with children with ulcerative colitis or IBD-unclassified.

Background Anti–tumor necrosis factor–α (anti-TNF-α) treatments are increasingly used to treat pediatric Crohn’s disease, even without a prior trial of immunomodulators, but the cost-effectiveness of such treatment algorithms has not been formally examined. Drug plan decision-makers require evidence of cost-effectiveness to inform funding decisions. The objective was to assess the incremental cost-effectiveness of early intervention with anti-TNF-α treatment vs a conventional step-up strategy per steroid-free remission-week gained from public health care and societal payer perspectives over 3 years. Methods A probabilistic microsimulation model was constructed for children with newly diagnosed moderate to severe Crohn’s disease receiving anti-TNF-α treatment and concomitant treatments within the first 3 months of diagnosis compared with children receiving standard care consisting of steroids and/or immunomodulators with the possibility of anti-TNF-α treatment after 3 months of diagnosis. A North American multicenter observational study with 360 patients provided input into clinical outcomes and health care resource use. Results Early intervention with anti-TNF-α treatment was more costly, with an incremental cost of CAD$31,112 (95% confidence interval [CI], $2939–$91,715), and more effective, with 11.3 more weeks in steroid-free remission (95% CI, 10.6–11.6) compared with standard care, resulting in an incremental cost per steroid-free remission-week gained of CAD$2756 from an Ontario public health care perspective and CAD$2968 from a societal perspective. The incremental cost-effectiveness ratio was sensitive to the price of infliximab. Conclusions The results suggest that although early anti-TNF-α was not cost-effective, it was clinically beneficial. These findings, along with other randomized controlled trial evidence, may inform formulary decision-making.

Background & AimsWe aim to provide guidance for medical treatment of luminal Crohn’s disease in children.MethodsWe performed a systematic search of publication databases to identify studies of medical management of pediatric Crohn’s disease. Quality of evidence and strength of recommendations were rated according to the GRADE (Grading of Recommendation Assessment, Development, and Evaluation) approach. We developed statements through an iterative online platform and then finalized and voted on them.ResultsThe consensus includes 25 statements focused on medical treatment options. Consensus was not reached, and no recommendations were made, for 14 additional statements, largely due to lack of evidence. The group suggested corticosteroid therapies (including budesonide for mild to moderate disease). The group suggested exclusive enteral nutrition for induction therapy and biologic tumor necrosis factor antagonists for induction and maintenance therapy at diagnosis or at early stages of severe disease, and for patients failed by steroid and immunosuppressant induction therapies. The group recommended against the use of oral 5-aminosalicylate for induction or maintenance therapy in patients with moderate disease, and recommended against thiopurines for induction therapy, corticosteroids for maintenance therapy, and cannabis in any role. The group was unable to clearly define the role of concomitant immunosuppressants during initiation therapy with a biologic agent, although thiopurine combinations are not recommended for male patients. No consensus was reached on the role of aminosalicylates in treatment of patients with mild disease, antibiotics or vedolizumab for induction or maintenance therapy, or methotrexate for induction therapy. Patients in clinical remission who are receiving immunomodulators should be assessed for mucosal healing within 1 year of treatment initiation.ConclusionsEvidence-based medical treatment of Crohn’s disease in children is recommended, with thorough ongoing assessments to define treatment success.

Dieulafoy's lesion (DL) is a small gastrointestinal (GI) mucosal erosion due to an abnormally large caliber and persistent submucosal arteriole. Typically occurring in adults, they are an extremely rare cause of GI bleeding in pediatrics. We report a case of multiple jejunal DLs in a 9-year-old girl with posterior fossa brain malformations, hemangiomas, arterial lesions, cardiac abnormalities, eye abnormalities (PHACE) syndrome, and the first described use of rapamycin in the treatment of pediatric DLs.

Background Infliximab pharmacokinetics in steroid-refractory [SR] ulcerative colitis [UC] suggest a need for higher dosing, but data concerning efficacy of intensification in this setting are lacking in children and inconsistent overall. Methods Paediatric patients [N = 125] treated with infliximab for SR or steroid-dependent UC were retrospectively reviewed. Outcomes [clinical response and remission, colectomy, mucosal healing, safety] with standard vs intensified induction [mean induction dose ≥7 mg/kg or interval ≤5 weeks between doses 1 and 3] were compared. Results Among 125 patients [median age 14 years, median UC duration 0.7 years, 74 SR], 73 [58%] received standard induction and 52 [42%] received intensified induction. Overall, 73 [58%] achieved remission (judged by physician global assessment [PGA] and paediatric UC activity index [PUCAI]≤10]. Among patients in remission, 7 [10%] experienced secondary loss of response by a median of 0.7 [IQR 0.4–1.0] years. Of the 74 SR patients, 17 [23%] underwent colectomy, and of the 51 steroid-dependent patients, 12 [24%] underwent colectomy. Intensified induction in SR patients was associated with a higher chance of remission (hazard ratio [HR] 3.2, p = 0.02) and a lower chance of colectomy [HR 0.4, p = 0.05], but did not improve outcomes in steroid-dependent patients. During follow-up, 46/73 [63%] patients in remission had regimen individualization, with similar rates of return to standard dosing after 1 year between those with initial intensified or standard induction. Follow-up endoscopy, performed in 35/73 patients in remission, demonstrated mucosal healing for 66%. Adverse events were rare, despite use of intensified regimens. Conclusions These data suggest a benefit from intensified infliximab induction specifically among children with steroid-refractory UC. Prospective studies comparing dosing regimens and incorporating therapeutic drug monitoring should be undertaken.

Vitamin D deficiency is an environmental factor involved in the pathogenesis of inflammatory bowel disease (IBD); however, the mechanisms surrounding its role remain unclear. Previous studies conducted in an intestinal epithelial-specific vitamin D receptor (VDR) knockout model suggest that a lack of vitamin D signaling causes a reduction in intestinal autophagy. A potential link between vitamin D deficiency and dysregulated autophagy is microRNA (miR)-142-3p, which suppresses autophagy. In this study, we found that wild-type C57BL/6 mice fed a vitamin D-deficient diet for 5 wk had increased miR-142-3p expression in ileal tissues compared with mice that were fed a matched control diet. Interestingly, there was no difference in expression of key autophagy markers ATG16L1 and LC3II in the ileum whole tissue. However, Paneth cells of vitamin D-deficient mice were morphologically abnormal and had an accumulation of the autophagy adaptor protein p62, which was not present in the total crypt epithelium. These findings suggest that Paneth cells exhibit early markers of autophagy dysregulation within the intestinal epithelium in response to vitamin D deficiency and enhanced miR-142-3p expression. Finally, we demonstrated that treatment-naïve IBD patients with low levels of vitamin D have an increase in miR-142-3p expression in colonic tissues procured from "involved" areas of the disease. Taken together, our findings demonstrate that insufficient vitamin D levels alter expression of autophagy-regulating miR-142-3p in intestinal tissues of mice and patients with IBD, providing insight into the mechanisms by which vitamin D deficiency modulates IBD pathogenesis.

Background Paediatric data on the association between diagnostic delay and inflammatory bowel disease [IBD] complications are lacking. We aimed to determine the effect of diagnostic delay on stricturing/fistulising complications, surgery, and growth impairment in a large paediatric cohort, and to identify predictors of diagnostic delay. Methods We conducted a national, prospective, multicentre IBD inception cohort study including 1399 children. Diagnostic delay was defined as time from symptom onset to diagnosis >75th percentile. Multivariable proportional hazards [PH] regression was used to examine the association between diagnostic delay and stricturing/fistulising complications and surgery, and multivariable linear regression to examine the association between diagnostic delay and growth. Predictors of diagnostic delay were identified using Cox PH regression. Results Overall (64% Crohn’s disease [CD]; 36% ulcerative colitis/IBD unclassified [UC/IBD-U]; 57% male]), median time to diagnosis was 4.2 (interquartile range [IQR] 2.0–9.2) months. For the overall cohort, diagnostic delay was >9.2 months; in CD, >10.8 months and in UC/IBD-U, >6.6 months. In CD, diagnostic delay was associated with a 2.5-fold higher rate of strictures/internal fistulae (hazard ratio [HR] 2.53, 95% confidence interval [CI] 1.41–4.56). Every additional month of diagnostic delay was associated with a decrease in height-for-age z-score of 0.013 standard deviations [95% CI 0.005–0.021]. Associations persisted after adjusting for disease location and therapy. No independent association was observed between diagnostic delay and surgery in CD or UC/IBD-U. Diagnostic delay was more common in CD, particularly small bowel CD. Abdominal pain, including isolated abdominal pain in CD, was associated with diagnostic delay. Conclusions Diagnostic delay represents a risk factor for stricturing/internal fistulising complications and growth impairment in paediatric CD. Podcast This article has an associated podcast which can be accessed at https://academic.oup.com/ecco-jcc/pages/podcast

Background The paediatric inflammatory bowel disease (PIBD) classes algorithm was developed to bring consistency to labelling of colonic IBD, but labels are exclusively based on features atypical for ulcerative colitis (UC). Aim The aim of the study was to develop an algorithm and identify features that discriminate between paediatric UC and colonic Crohn disease (CD). Methods Baseline clinical, endoscopic, radiologic, and histologic data, including the PIBD class features in 74 colonic IBD (56: UC, 18: colonic CD) patients were collected. The PIBD class features and additional features common to UC were used to perform initial clustering, using similarity network fusion (SNF). We trained a Random Forest (RF) classifier on the full dataset and used a leave-one-out approach to evaluate model accuracy. The top-features were used to build a new classifier, which we tested on 15 previously unused patients. We then performed clustering with SNF on the top RF features and assessed ability to discriminate between UC and colonic-CD independent of a supervised model. Results The initial SNF clustering with 58 patients demonstrated 2 groups: group 1 (n = 39, 90% UC) and group 2 (n = 19, 68% colonic-CD). Our RF classifier correctly labelled 97% of the 58 patients based on leave-one-out cross validation and identified the 7 most important features (3 histological and 4 endoscopic) to clinically distinguish these groups. We trained a new RF classifier with the top 7 features and found 100% accuracy in a set of 15 held-out patients. Finally, post hoc clustering with these 7 features revealed 2 groups of patients: group 1 (n = 55, 98% UC) and group 2 (n = 18, 94% colonic-CD). Conclusions: A combination of supervised and unsupervised analyses identified a short list of features, which consistently distinguish UC from colonic CD. Future directions include validation in other populations.

Background and Aims Ileal strictures are the major indication for resective surgery in Crohn’s disease [CD]. We aimed to define ileal gene programmes present at diagnosis and linked with future stricturing behaviour during 5-year follow-up, and to identify potential small molecules to reverse these gene signatures. Methods Antimicrobial serologies and pre-treatment ileal gene expression were assessed in a representative subset of 249 CD patients within the RISK multicentre paediatric CD inception cohort study, including 113 that are unique to this report. These data were used to define genes associated with stricturing behaviour and for model testing to predict stricturing behaviour. A bioinformatics approach to define small molecules which may reverse the stricturing gene signature was applied. Results A total of 19 of the 249 patients developed isolated B2 stricturing behaviour during follow-up, while 218 remained B1 inflammatory. Using deeper RNA sequencing than in our previous report, we have now defined an inflammatory gene signature including an oncostatin M co-expression signature, tightly associated with extra-cellular matrix [ECM] gene expression, in those who developed stricturing complications. We further computationally prioritise small molecules targeting macrophage and fibroblast activation and angiogenesis which may reverse the stricturing gene signature. A model containing ASCA and CBir1 serologies and a refined eight ECM gene set was significantly associated with stricturing development by Year 5 after diagnosis {AUC (area under the curve) (95th CI [confidence interval]) = 0.82 [0.7–0.94)}. Conclusions An ileal gene programme for macrophage and fibroblast activation is linked to stricturing complications in treatment of naïve pediatric CD, and may inform novel small molecule therapeutic approaches.

IntroductionPatients with paediatric-onset inflammatory bowel disease (PIBD) may develop a complicated disease course, including growth failure, bowel resection at young age and treatment-related adverse events, all of which can have significant and lasting effects on the patient’s development and quality of life. Unfortunately, we are still not able to fully explain the heterogeneity between patients and their disease course and predict which patients will respond to certain therapies or are most at risk of developing a more complicated disease course. To investigate this, large prospective studies with long-term follow-up are needed. Currently, no such European or Asian international cohorts exist. In this international cohort, we aim to evaluate disease course and which patients are most at risk of therapy non-response or development of complicated disease based on patient and disease characteristics, immune pathology and environmental and socioeconomic factors.Methods and analysisIn this international prospective observational study, which is part of the PIBD Network for Safety, Efficacy, Treatment and Quality improvement of care (PIBD-SETQuality), children diagnosed with inflammatory bowel disease Ethics and disseminationMedical ethical approval has been obtained prior to patient recruitment for all sites. The results will be disseminated through peer-reviewed scientific publications.Trial registration numberNCT03571373.

OBJECTIVES: The aim of this study was to assess common laboratory tests in identifying severe ulcerative colitis in children at diagnosis. METHODS: A cohort of 427 children 4 to 17 years of age newly diagnosed with ulcerative colitis (UC) was prospectively enrolled. Boosted classification trees were used to characterize predictive ability of disease attributes based on clinical disease severity using Pediatric Ulcerative Colitis Activity Index (PUCAI), severe (65+) versus not severe (

BACKGROUND & AIMS: A better understanding of prognostic factors in ulcerative colitis (UC) could improve patient management and reduce complications. We aimed to identify evidence-based predictors for outcomes in pediatric UC, which may be used to optimize treatment algorithms. METHODS: Potential outcomes worthy of prediction in UC were determined by surveying 202 experts in pediatric UC. A systematic review of the literature, with selected meta-analysis, was performed to identify studies that investigated predictors for these outcomes. Multiple national and international meetings were held to reach consensus on evidence-based statements. RESULTS: Consensus was reached on 31 statements regarding predictors of colectomy, acute severe colitis (ASC), chronically active pediatric UC, cancer and mortality. At diagnosis, disease extent (6 studies, N = 627; P = .035), Pediatric Ulcerative Colitis Activity Index score (4 studies, n = 318; P < .001), hemoglobin, hematocrit, and albumin may predict colectomy. In addition, family history of UC (2 studies, n = 557; P = .0004), extraintestinal manifestations (4 studies, n = 526; P = .048), and disease extension over time may predict colectomy, whereas primary sclerosing cholangitis (PSC) may be protective. Acute severe colitis may be predicted by disease severity at onset and hypoalbuminemia. Higher Pediatric Ulcerative Colitis Activity Index score and C-reactive protein on days 3 and 5 of hospital admission predict failure of intravenous steroids. Risk factors for malignancy included concomitant diagnosis of primary sclerosing cholangitis, longstanding colitis (>10 years), male sex, and younger age at diagnosis. CONCLUSIONS: These evidence-based consensus statements offer predictions to be considered for a personalized medicine approach in treating pediatric UC.

BACKGROUND & AIMS: A better understanding of prognostic factors within the heterogeneous spectrum of pediatric Crohn's disease (CD) should improve patient management and reduce complications. We aimed to identify evidence-based predictors of outcomes with the goal of optimizing individual patient management. METHODS: A survey of 202 experts in pediatric CD identified and prioritized adverse outcomes to be avoided. A systematic review of the literature with meta-analysis, when possible, was performed to identify clinical studies that investigated predictors of these outcomes. Multiple national and international face-to-face meetings were held to draft consensus statements based on the published evidence. RESULTS: Consensus was reached on 27 statements regarding prognostic factors for surgery, complications, chronically active pediatric CD, and hospitalization. Prognostic factors for surgery included CD diagnosis during adolescence, growth impairment, NOD2/CARD15 polymorphisms, disease behavior, and positive anti-Saccharomyces cerevisiae antibody status. Isolated colonic disease was associated with fewer surgeries. Older age at presentation, small bowel disease, serology (anti-Saccharomyces cerevisiae antibody, antiflagellin, and OmpC), NOD2/CARD15 polymorphisms, perianal disease, and ethnicity were risk factors for penetrating (B3) and/or stenotic disease (B2). Male sex, young age at onset, small bowel disease, more active disease, and diagnostic delay may be associated with growth impairment. Malnutrition and higher disease activity were associated with reduced bone density. CONCLUSIONS: These evidence-based consensus statements offer insight into predictors of poor outcomes in pediatric CD and are valuable when developing treatment algorithms and planning future studies. Targeted longitudinal studies are needed to further characterize prognostic factors in pediatric CD and to evaluate the impact of treatment algorithms tailored to individual patient risk.

Background Noninvasive and accurate methods to monitor inflammatory bowel disease are required. As a planned ancillary study of the prospective ImageKids cohort, we aimed to assess the performance of fecal calprotectin (FC) with comparison to 3 fecal inflammatory markers; S100A12 (FA12), tumor pyruvate kinase isoenzyme type M2 (FM2PK) and fecal osteoprotegerin (FOPG) as indicators of a number of disease characteristics. Methods The ImageKids study was a multicenter study designed to develop 2 magnetic resonance enterography-based measures for children with Crohn disease (6-18 years old). All patients underwent magnetic resonance enterography, a complete ileocolonoscopic evaluation and provided a fecal sample. Fecal samples were assay for FC, FA12, FM2PK, and FOPG by ELISA. Results One-hundred fifty-six children provided 190 fecal samples. Median (interquartile range) for fecal makers were FC, 602 (181-1185) μg/g; FA12, 21 (3-109) μg/g; FM2PK, 16 (2-20) U/mL; and FOPG, 125 (125-312) μg/g. All markers correlated with simple endoscopic severity index for Crohn disease and with other constructs of disease activity, but FC had the highest overall correlations. FA12, however, predicted mucosal healing with significantly higher specificity (87% vs 70%, P = 0.004) and equivalent sensitivity (91% vs 90%) compared to FC. Conclusion This study has confirmed that FC is useful, and overall best, marker to monitor mucosal inflammation in inflammatory bowel disease. FA12, however, appears to be a more suitable maker for prediction of mucosal healing in children.

Environmental factors play an important role in the pathogenesis of Crohn's Disease (CD). In particular, by virtue of the instability of the microbiome and development of immunologic tolerance, early life factors may exert the strongest influence on disease risk and phenotype.We used data from 1119 CD subjects recruited from RISK inception cohort to examine the impact of early life environment on disease progression. Our primary exposures of interest were breastfeeding in infancy and exposure to maternal, active, or passive smoke. Our primary outcomes were development of complicated (stricturing or penetrating) disease, and need for CD-related hospitalization, and surgery. Multivariable logistic regression models were used to define independent associations, adjusting for relevant covariates.Our study cohort included 1119 patients with CD among whom 15% had stricturing (B2) or penetrating disease (B3) by 3 years. 331 patients (35%) and 95 patients (10.6%) required CD-related hospitalizations and surgery respectively. 74.5% were breastfed in infancy and 31% were exposed to smoking among whom 7% were exposed to maternal smoke. On multivariable analysis, a history of breastfeeding was inversely associated with complicated (B2/B3 disease) 0.65, CI 95% 0.44-96; P = 0.03) in pediatric CD. Maternal smoking during pregnancy was associated with increased risk of hospitalization during the 3-year follow-up period (OR 1.75, CI 95% 1.05-2.89; P = 0.03).Early life environmental factors influence the eventual phenotypes and disease course in CD.

Author(s): Denson, Lee A; Jurickova, Ingrid; Karns, Rebekah; Shaw, Kelly A; Cutler, David J; Okou, David; Valencia, C Alexander; Dodd, Anne; Mondal, Kajari; Aronow, Bruce J; Haberman, Yael; Linn, Aaron; Price, Adam; Bezold, Ramona; Lake, Kathleen; Jackson, Kimberly; Walters, Thomas D; Griffiths, Anne; Baldassano, Robert N; Noe, Joshua D; Hyams, Jeffrey S; Crandall, Wallace V; Kirschner, Barbara S; Heyman, Melvin B; Snapper, Scott; Guthery, Stephen L; Dubinsky, Marla C; Leleiko, Neal S; Otley, Anthony R; Xavier, Ramnik J; Stevens, Christine; Daly, Mark J; Zwick, Michael E; Kugathasan, Subra | Abstract: BACKGROUND:Granulocyte-macrophage colony-stimulating factor auto-antibodies (GMAbs) suppress neutrophil-extrinsic GM-CSF signaling and increase risk for stricturing behavior in Crohn's disease (CD). We aimed to define clinical, genomic, and functional associations with neutrophil-intrinsic GM-CSF signaling. METHODS:Missense mutations in CSF2RA, CSF2RB, JAK2, STAT5A, and STAT5B were identified using whole-exome sequencing in 543 pediatric inflammatory bowel disease (IBD) patients. Neutrophil-intrinsic GM-CSF signaling was defined using the GM-CSF-induced STAT5 stimulation index (GMSI) in 180 pediatric IBD patients and 26 non-IBD controls. Reduced GM-CSF signaling (GMSI-Lo) was defined as the 20th percentile within the control group. Variation in neutrophil phospho-protein abundance, bacterial killing, and the global pattern of gene expression with the GMSI was determined. RESULTS:We validated 18 potentially damaging missense mutations in CSF2RA and CSF2RB. CSF2RA A17G carriage increased from 10% in those with intact neutrophil GMSI to 32% in those with low GMSI (P = 0.02). The frequency of reduced Staphylococcus aureus killing increased from 17% in those with intact neutrophil GMSI to 35% in GMSI-Lo neutrophils (P = 0.043). Crohn's disease neutrophils with low GMSI exhibited specific alterations in phospho-protein networks and genes regulating cytokine production, wound healing, and cell survival and proliferation. Stricturing behavior increased from 7% in patients with both low GMAb and intact GMSI to 64% in patients with both elevated GMAb and low GMSI (P l 0.0001). CONCLUSIONS:Low/normal neutrophil-intrinsic GM-CSF signaling is associated with CSF2RA missense mutations, alterations in gene expression networks, and higher rates of disease complications in pediatric CD.

Background & aimsIndividuals with monogenic disorders of phagocyte function develop chronic colitis that resembles Crohn's disease (CD). We tested for associations between mutations in genes encoding reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, neutrophil function, and phenotypes of CD in pediatric patients.MethodsWe performed whole-exome sequence analysis to identify mutations in genes encoding NADPH oxidases (such as CYBA, CYBB, NCF1, NCF2, NCF4, RAC1, and RAC2) using DNA from 543 pediatric patients with inflammatory bowel diseases. Blood samples were collected from an additional 129 pediatric patients with CD and 26 children without IBD (controls); we performed assays for neutrophil activation, reactive oxygen species (ROS) production, and bacteria uptake and killing. Whole-exome sequence analysis was performed using DNA from 46 of the children with CD to examine associations with NADPH gene mutations; RNA sequence analyses were performed using blood cells from 46 children with CD to test for variations in neutrophil gene expression associated with ROS production.ResultsWe identified 26 missense mutations in CYBA, CYBB, NCF1, NCF2, and NCF4. Patients with CD who carried mutations in these genes were 3-fold more likely to have perianal disease (P= .0008) and stricturing complications (P= .002) than children with CD without these mutations. Among patients withCD with none of these mutations, 9% had undergone abdominal surgery; among patients with mutations in these NADPH oxidase genes, 31% had undergone abdominal surgery (P=.0004). A higher proportion of neutrophils from children with CD had low ROS production (47%) than from controls (15%) among the 129 patients tested for ROS (P= .002). Minor alleles of the NADPH genes were detected in 7% of children with CD whose neutrophils produced normal levels of ROS vs 38% of children whose neutrophils produced low levels of ROS (P= .009). Neutrophils that produced low levels of ROS had specific alterations in genes that regulate glucose metabolism and antimicrobial responses.ConclusionsWe identified missense mutations in genes that encode NADPH oxidases in children with CD; these were associated with a more aggressive disease course and reduced ROS production by neutrophils from the patients.