Genetic variation in severe cystic fibrosis liver disease is associated with novel mechanisms for disease pathogenesis.

BACKGROUND AND AIMS: It is not known why severe cystic fibrosis (CF) liver disease (CFLD) with portal hypertension occurs in only ~7% of people with CF. We aimed to identify genetic modifiers for severe CFLD to improve understanding of disease mechanisms. APPROACH AND RESULTS: Whole-genome sequencing was available in 4082 people with CF with pancreatic insufficiency (n = 516 with severe CFLD; n = 3566 without CFLD). We tested ~15.9 million single nucleotide polymorphisms (SNPs) for association with severe CFLD versus no-CFLD, using pre-modulator clinical phenotypes including (1) genetic variant ( SERPINA1 ; Z allele) previously associated with severe CFLD; (2) candidate SNPs (n = 205) associated with non-CF liver diseases; (3) genome-wide association study of common/rare SNPs; (4) transcriptome-wide association; and (5) gene-level and pathway analyses. The Z allele was significantly associated with severe CFLD ( p = 1.1 × 10 -4 ). No significant candidate SNPs were identified. A genome-wide association study identified genome-wide significant SNPs in 2 loci and 2 suggestive loci. These 4 loci contained genes [significant, PKD1 ( p = 8.05 × 10 -10 ) and FNBP1 ( p = 4.74 × 10 -9 ); suggestive, DUSP6 ( p = 1.51 × 10 -7 ) and ANKUB1 ( p = 4.69 × 10 -7 )] relevant to severe CFLD pathophysiology. The transcriptome-wide association identified 3 genes [ CXCR1 ( p = 1.01 × 10 -6 ) , AAMP ( p = 1.07 × 10 -6 ), and TRBV24 ( p = 1.23 × 10 -5 )] involved in hepatic inflammation and innate immunity. Gene-ranked analyses identified pathways enriched in genes linked to multiple liver pathologies. CONCLUSION: These results identify loci/genes associated with severe CFLD that point to disease mechanisms involving hepatic fibrosis, inflammation, innate immune function, vascular pathology, intracellular signaling, actin cytoskeleton and tight junction integrity and mechanisms of hepatic steatosis and insulin resistance. These discoveries will facilitate mechanistic studies and the development of therapeutics for severe CFLD.

Immunoreactive trypsinogen levels in newborn screened infants with an inconclusive diagnosis of cystic fibrosis.

BACKGROUND: Newborn screening (NBS) for cystic fibrosis (CF) not only identifies infants with a diagnosis of CF, but also those with an uncertain diagnosis of cystic fibrosis (CF), i.e. CF transmembrane conductance regulator (CFTR)-related metabolic syndrome (CRMS) or CF screen positive inconclusive diagnosis (CFSPID). These infants have an uncertain long-term outcome and it is currently unclear around time of diagnosis, which infants are at higher risk of later fulfilling a CF diagnosis. In this study, we hypothesised that immunoreactive trypsinogen (IRT) levels, used in NBS as a marker of pancreatic disease and function, may reflect the degree of CFTR dysfunction in each individual and therefore would help to identify those with CRMS/CSPID who are later at risk for meeting the criteria of CF. METHODS: In this longitudinal, prospective study, infants with CRMS/CFSPID and CF were recruited and followed in 9 CF clinics (Canada and Italy). We compared NBS IRT levels between CF and CRMS/CFSPID, and between children with CRMS/CFSPID→CF and CRMS/CFSPID→CRMS/CFSPID during the period of June 2007 to April 2016. RESULTS: Ninety eight CRMS/CFSPID and 120 CF subjects were enrolled. During the study period, 14 (14.3%) CRMS/CFSPID subjects fulfilled the diagnostic criteria for CF (CRMS/CFSPID→CF), while the diagnosis remained uncertain (CRMS/CFSPID→ CRMS/CFSPID) in 84 (85.7%) subjects. Significantly higher NBS IRT concentrations (ng/ml) were present in CF than CRMS/CFPSID (median (interquartile range): 143.8 (99.8-206.2) vs. 75.0 (61.0-105.9); P < 0.0001). Infants with CRMS/CFSPID→CF (n = 14) had significantly higher NBS IRT concentrations (ng/ml) than CRMS/CFSPID→ CRMS/CFSPID (n = 83) (median (interquartile range): 108.9 (72.3-126.8) vs. 73.7(60.0-96.0); P = 0.02). CONCLUSIONS: Amongst infants who tested positive on NBS for CF, there is a gradation of elevated NBS IRT concentrations. Infants with CF have higher NBS IRT levels than CRMS/CFPSID, and higher NBS IRT concentrations were present in infants with CRMS/CFSPID→CF than CRMS/CFSPID→ CRMS/CFSPID. NBS IRT concentrations, in concert with other factors, may have the potential to predict the likelihood of CF amongst infants with CRMS/CFSPID.

Analysis of a large cohort of cystic fibrosis patients with severe liver disease indicates lung function decline does not significantly differ from that of the general cystic fibrosis population.

Previous reports of lung function in cystic fibrosis (CF) patients with liver disease have shown worse, similar, or even better forced expiratory volume in 1 second (FEV1), compared to CF patients without liver disease. Varying definitions of CF liver disease likely contribute to these inconsistent relationships reported between CF lung function and liver disease. We retrospectively evaluated spirometric data in 179 subjects (62% male; 58% Phe508del homozygous) with severe CF liver disease (CFLD; defined by presence of portal hypertension due to cirrhosis). FEV1 values were referenced to both a normal population (FEV1% predicted) and CF population (CF-specific FEV1 percentile). We utilized a linear mixed model with repeated measures to assess changes in lung function (before and after diagnosis of CFLD), relative to both the normal and CF populations. At diagnosis of CFLD, the mean FEV1 was 81% predicted, or at the 53rd percentile referenced to CF patients without CFLD. There was a significant difference in post-CFLD slope compared to pre-CFLD slope (post-pre) using FEV1% predicted (-1.94, p-value < 0.0001). However, there was insignificant evidence of this difference using the CF-specific FEV1 percentile measure (-0.99, p-value = 0.1268). Although FEV1% predicted values declined in patients following CFLD diagnosis, there was not significant evidence of lung function decline in CF-specific FEV1 percentiles. Thus, the observed study cohort indicates diagnosis of severe CFLD was not associated with worsened CF lung disease when compared to a large CF reference population.

Airway Mucosal Host Defense Is Key to Genomic Regulation of Cystic Fibrosis Lung Disease Severity.

RATIONALE: The severity of cystic fibrosis (CF) lung disease varies widely, even for Phe508del homozygotes. Heritability studies show that more than 50% of the variability reflects non-cystic fibrosis transmembrane conductance regulator (CFTR) genetic variation; however, the full extent of the pertinent genetic variation is not known. OBJECTIVES: We sought to identify novel CF disease-modifying mechanisms using an integrated approach based on analyzing "in vivo" CF airway epithelial gene expression complemented with genome-wide association study (GWAS) data. METHODS: Nasal mucosal RNA from 134 patients with CF was used for RNA sequencing. We tested for associations of transcriptomic (gene expression) data with a quantitative phenotype of CF lung disease severity. Pathway analysis of CF GWAS data (n = 5,659 patients) was performed to identify novel pathways and assess the concordance of genomic and transcriptomic data. Association of gene expression with previously identified CF GWAS risk alleles was also tested. MEASUREMENTS AND MAIN RESULTS: Significant evidence of heritable gene expression was identified. Gene expression pathways relevant to airway mucosal host defense were significantly associated with CF lung disease severity, including viral infection, inflammation/inflammatory signaling, lipid metabolism, apoptosis, ion transport, Phe508del CFTR processing, and innate immune responses, including HLA (human leukocyte antigen) genes. Ion transport and CFTR processing pathways, as well as HLA genes, were identified across differential gene expression and GWAS signals. CONCLUSIONS: Transcriptomic analyses of CF airway epithelia, coupled to genomic (GWAS) analyses, highlight the role of heritable host defense variation in determining the pathophysiology of CF lung disease. The identification of these pathways provides opportunities to pursue targeted interventions to improve CF lung health.

Therapeutic Endoscopic Retrograde Cholangiopancreatography in Pediatric Patients With Acute Recurrent and Chronic Pancreatitis: Data From the INSPPIRE (INternational Study group of Pediatric Pancreatitis: In search for a cuRE) Study.

OBJECTIVE: The aim of this study was to characterize utilization and benefit of therapeutic endoscopic retrograde cholangiopancreatography (ERCP) in children with acute recurrent pancreatitis (ARP) or chronic pancreatitis (CP). METHODS: From August 2012 to February 2015, 301 children with ARP or CP were enrolled in the INSPPIRE (INternational Study group of Pediatric Pancreatitis: In search for a cuRE) study. Physicians reported utilization and benefit of therapeutic ERCP at enrollment. Differences were analyzed using appropriate statistical methods. RESULTS: One hundred seventeen children (38.9%) underwent at least 1 therapeutic ERCP. The procedure was more commonly performed in children with CP compared with those with ARP (65.8% vs 13.5%, P < 0.0001). Utility of therapeutic ERCP was reported to be similar between ARP and CP (53% vs 56%, P = 0.81) and was found to be helpful for at least 1 indication in both groups (53/99 patients [53.5%]). Predictors for undergoing therapeutic ERCP were presence of obstructive factors in ARP and CP, Hispanic ethnicity, or white race in CP. CONCLUSIONS: Therapeutic ERCP is frequently utilized in children with ARP or CP and may offer benefit in selected cases, specifically if ductal obstruction is present. Longitudinal studies are needed to clarify the efficacy of therapeutic ERCP and to explore subgroups that might have increased benefit from such intervention.

Genome-wide association study of primary sclerosing cholangitis identifies new risk loci and quantifies the genetic relationship with inflammatory bowel disease.

Primary sclerosing cholangitis (PSC) is a rare progressive disorder leading to bile duct destruction; ∼75% of patients have comorbid inflammatory bowel disease (IBD). We undertook the largest genome-wide association study of PSC (4,796 cases and 19,955 population controls) and identified four new genome-wide significant loci. The most associated SNP at one locus affects splicing and expression of UBASH3A, with the protective allele (C) predicted to cause nonstop-mediated mRNA decay and lower expression of UBASH3A. Further analyses based on common variants suggested that the genome-wide genetic correlation (rG) between PSC and ulcerative colitis (UC) (rG = 0.29) was significantly greater than that between PSC and Crohn's disease (CD) (rG = 0.04) (P = 2.55 × 10-15). UC and CD were genetically more similar to each other (rG = 0.56) than either was to PSC (P < 1.0 × 10-15). Our study represents a substantial advance in understanding of the genetics of PSC.

Risk Factors Associated With Pediatric Acute Recurrent and Chronic Pancreatitis: Lessons From INSPPIRE.

IMPORTANCE: Pediatric acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) are poorly understood. OBJECTIVE: To characterize and identify risk factors associated with ARP and CP in childhood. DESIGN, SETTING, AND PARTICIPANTS: A multinational cross-sectional study of children with ARP or CP at the time of enrollment to the INSPPIRE (International Study Group of Pediatric Pancreatitis: In Search for a Cure) study at participant institutions of the INSPPIRE Consortium. From August 22, 2012, to February 8, 2015, 155 children with ARP and 146 with CP (aged ≤19 years) were enrolled. Their demographic and clinical information was entered into the REDCap (Research Electronic Data Capture) database at the 15 centers. Differences were analyzed using 2-sample t test or Wilcoxon rank sum test for continuous variables and Pearson χ2 test or Fisher exact test for categorical variables. Disease burden variables (pain variables, hospital/emergency department visits, missed school days) were compared using Wilcoxon rank sum test. MAIN OUTCOMES AND MEASURES: Demographic characteristics, risk factors, abdominal pain, and disease burden. RESULTS: A total of 301 children were enrolled (mean [SD] age, 11.9 [4.5] years; 172 [57%] female); 155 had ARP and 146 had CP. The majority of children with CP (123 of 146 [84%]) reported prior recurrent episodes of acute pancreatitis. Sex distribution was similar between the groups (57% female in both). Hispanic children were less likely to have CP than ARP (17% vs 28%, respectively; odds ratio [OR] = 0.51; 95% CI, 0.29-0.92; P = .02). At least 1 gene mutation in pancreatitis-related genes was found in 48% of patients with ARP vs 73% of patients with CP (P < .001). Children with PRSS1 or SPINK1 mutations were more likely to present with CP compared with ARP (PRSS1: OR = 4.20; 95% CI, 2.14-8.22; P < .001; and SPINK1: OR = 2.30; 95% CI, 1.03-5.13; P = .04). Obstructive risk factors did not differ between children with ARP or CP (33% in both the ARP and CP groups), but toxic/metabolic risk factors were more common in children with ARP (21% overall; 26% in the ARP group and 15% in the CP group; OR = 0.55; 95% CI, 0.31-0.99; P = .046). Pancreatitis-related abdominal pain was a major symptom in 81% of children with ARP or CP within the last year. The disease burden was greater in the CP group compared with the ARP group (more emergency department visits, hospitalizations, and medical, endoscopic, and surgical interventions). CONCLUSIONS AND RELEVANCE: Genetic mutations are common in both ARP and CP. Ethnicity and mutations in PRSS1 or SPINK1 may influence the development of CP. The high disease burden in pediatric CP underscores the importance of identifying predisposing factors for progression of ARP to CP in children.

Features of Severe Liver Disease With Portal Hypertension in Patients With Cystic Fibrosis.

BACKGROUND & AIMS: Liver disease is the third leading cause of death in patients with cystic fibrosis (CF), but features of patients with CF, severe liver disease, and portal hypertension have not been characterized fully. METHODS: We performed a retrospective analysis of data from 561 patients with CF (63% male, 99% with pancreatic insufficiency), liver disease (hepatic parenchymal abnormalities consistent with cirrhosis, confirmed by imaging), and portal hypertension (esophageal varices, portosystemic collaterals, or splenomegaly), with no alternate causes of liver disease. All patients were enrolled in the Genetic Modifier Study of Severe CF Liver Disease at 76 international centers, from January 1999 through July 2013. RESULTS: Male patients were diagnosed with liver disease at a younger age than female patients (10 vs 11 y; P = .01). Splenomegaly was observed in 99% of patients and varices in 71%. Levels of liver enzymes were near normal in most patients. Thrombocytopenia affected 70% of patients and was more severe in patients with varices (88 × 10(9)/L vs 145 × 10(9)/L; P < .0001). Ninety-one patients received liver transplants (16%), at a median age of 13.9 years. Compared with patients who did not receive liver transplants, patients who received liver transplants had lower platelet counts (78 × 10(9)/L vs 113 × 10(9)/L; P < .0001), higher international normalized ratios (P < .0001), and lower levels of albumin (P = .0002). The aminotransferase to platelet ratio index (APRi) and fibrosis index based on 4 factor (FIB-4) values were higher than the diagnostic thresholds for CF liver disease in 96% and in 90% of patients, respectively. Patients who received liver transplants or who had varices had higher APRi and FIB-4 values than patients who did not. CONCLUSIONS: In patients with CF, severe liver disease develops early in childhood (approximately 10 years of age), and is more common in boys than in girls. Patients with varices and those who receive liver transplants have more abnormal platelet counts and APRi and FIB-4 scores.

Cystic fibrosis from the gastroenterologist's perspective.

Cystic fibrosis is a life-limiting, recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Increased survival outcomes and the multisystem nature of the disease, including the involvement of hepatobiliary and gastrointestinal tracts, now require the need for more extensive knowledge and expertise in cystic fibrosis among gastroenterologists. Manifestations are either a direct consequence of the primary defect in cystic fibrosis or a secondary complication of the disease or therapy. Adult patients with cystic fibrosis also have an increased risk of malignancy in the gastrointestinal and pancreatico-biliary tracts compared with the general population. Novel treatments that target the basic defects in the CFTR protein have emerged, but to date not much is known about their effects on the gastrointestinal and hepatobiliary systems. The introduction of such therapies has provided new opportunities for the application of intestinal endpoints in clinical trials and the understanding of underlying disease mechanisms that affect the gut in cystic fibrosis.

Direct Costs of Acute Recurrent and Chronic Pancreatitis in Children in the INSPPIRE Registry.

OBJECTIVE: To estimate selected direct medical care costs of children with chronic pancreatitis (CP) and acute recurrent pancreatitis (ARP). METHODS: We performed a cross-sectional study of data from International Study Group of Pediatric Pancreatitis: In Search for a Cure (INSPPIRE), a multinational registry of children with ARP or CP. We determined health care utilization and estimated costs of hospitalizations, surgical and endoscopic procedures, and medications in our study population. Health care utilization data were obtained from all subjects enrolled in the study, and costs were calculated using national United States costs. RESULTS: We included 224 subjects (median age 12.7 years), 42% of whom had CP. Mean number of hospitalizations, including for surgery and endoscopic retrograde cholangiopancreatography, was 2.3 per person per year, costing an estimated average $38,755 per person per year. Including outpatient medications, estimated total mean cost was $40,589 per person per year. Subjects using surgical procedures or endoscopic retrograde cholangiopancreatography incurred mean annual costs of $42,951 per person and $12,035 per person, respectively. Estimated annual costs of pancreatic enzyme replacement therapy, diabetic medications, and pain medications were $4114, $1761, and $614 per person, respectively. In an exploratory analysis, patients with the following characteristics appear to accrue higher costs than those without them: more frequent ARP attacks per year, reported constant or episodic pain, family history of pancreatic cancer, and use of pain medication. CONCLUSIONS: ARP and CP are uncommon childhood conditions. The severe burden of disease associated with these conditions and their chronicity results in high health care utilization and costs. Interventions that reduce the need for hospitalization could lower costs for these children and their families.

Genome-wide association meta-analysis identifies five modifier loci of lung disease severity in cystic fibrosis.

The identification of small molecules that target specific CFTR variants has ushered in a new era of treatment for cystic fibrosis (CF), yet optimal, individualized treatment of CF will require identification and targeting of disease modifiers. Here we use genome-wide association analysis to identify genetic modifiers of CF lung disease, the primary cause of mortality. Meta-analysis of 6,365 CF patients identifies five loci that display significant association with variation in lung disease. Regions on chr3q29 (MUC4/MUC20; P=3.3 × 10(-11)), chr5p15.3 (SLC9A3; P=6.8 × 10(-12)), chr6p21.3 (HLA Class II; P=1.2 × 10(-8)) and chrXq22-q23 (AGTR2/SLC6A14; P=1.8 × 10(-9)) contain genes of high biological relevance to CF pathophysiology. The fifth locus, on chr11p12-p13 (EHF/APIP; P=1.9 × 10(-10)), was previously shown to be associated with lung disease. These results provide new insights into potential targets for modulating lung disease severity in CF.

A Joint Location-Scale Test Improves Power to Detect Associated SNPs, Gene Sets, and Pathways.

Gene-based, pathway, and other multivariate association methods are motivated by the possibility of GxG and GxE interactions; however, accounting for such interactions is limited by the challenges associated with adequate modeling information. Here we propose an easy-to-implement joint location-scale (JLS) association testing framework for single-variant and multivariate analysis that accounts for interactions without explicitly modeling them. We apply the JLS method to a gene-set analysis of cystic fibrosis (CF) lung disease, which is influenced by multiple environmental and genetic factors. We identify and replicate an association between the constituents of the apical plasma membrane and CF lung disease (p = 0.0099 and p = 0.0180, respectively) and highlight a role for the SLC9A3-SLC9A3R1/2-EZR complex in contributing to CF lung disease. Many association studies could benefit from re-analysis with the JLS method that leverages complex genetic architecture for SNP, gene, and pathway identification. Analytical verification, simulation, and additional proof-of-principle applications support our approach.

In Vivo Senescence in the Sbds-Deficient Murine Pancreas: Cell-Type Specific Consequences of Translation Insufficiency.

Genetic models of ribosome dysfunction show selective organ failure, highlighting a gap in our understanding of cell-type specific responses to translation insufficiency. Translation defects underlie a growing list of inherited and acquired cancer-predisposition syndromes referred to as ribosomopathies. We sought to identify molecular mechanisms underlying organ failure in a recessive ribosomopathy, with particular emphasis on the pancreas, an organ with a high and reiterative requirement for protein synthesis. Biallelic loss of function mutations in SBDS are associated with the ribosomopathy Shwachman-Diamond syndrome, which is typified by pancreatic dysfunction, bone marrow failure, skeletal abnormalities and neurological phenotypes. Targeted disruption of Sbds in the murine pancreas resulted in p53 stabilization early in the postnatal period, specifically in acinar cells. Decreased Myc expression was observed and atrophy of the adult SDS pancreas could be explained by the senescence of acinar cells, characterized by induction of Tgfß, p15(Ink4b) and components of the senescence-associated secretory program. This is the first report of senescence, a tumour suppression mechanism, in association with SDS or in response to a ribosomopathy. Genetic ablation of p53 largely resolved digestive enzyme synthesis and acinar compartment hypoplasia, but resulted in decreased cell size, a hallmark of decreased translation capacity. Moreover, p53 ablation resulted in expression of acinar dedifferentiation markers and extensive apoptosis. Our findings indicate a protective role for p53 and senescence in response to Sbds ablation in the pancreas. In contrast to the pancreas, the Tgfß molecular signature was not detected in fetal bone marrow, liver or brain of mouse models with constitutive Sbds ablation. Nevertheless, as observed with the adult pancreas phenotype, disease phenotypes of embryonic tissues, including marked neuronal cell death due to apoptosis, were determined to be p53-dependent. Our findings therefore point to cell/tissue-specific responses to p53-activation that include distinction between apoptosis and senescence pathways, in the context of translation disruption.

Inconclusive diagnosis of cystic fibrosis after newborn screening.

OBJECTIVES: To prospectively study infants with an inconclusive diagnosis of cystic fibrosis (CF) identified by newborn screening (NBS; "CF screen positive, inconclusive diagnosis" [CFSPID]) for disease manifestations. METHODS: Infants with CFSPID and CF based on NBS from 8 CF centers were prospectively evaluated and monitored. Genotype, phenotype, repeat sweat test, serum trypsinogen, and microbiology data were compared between subjects with CF and CFSPID and between subjects with CFSPID who did (CFSPID→CF) and did not (CFSPID→CFSPID) fulfill the criteria for CF during the first 3 years of life. RESULTS: Eighty-two subjects with CFSPID and 80 subjects with CF were enrolled. The ratio of CFSPID to CF ranged from 1:1.4 to 1:2.9 in different centers. CFTR mutation rates did not differ between groups; 96% of subjects with CFSPID and 93% of subjects with CF had 2 mutations. Subjects with CFSPID had significantly lower NBS immunoreactive trypsinogen (median [interquartile range]:77 [61-106] vs 144 [105-199] µg/L; P < .0001) than did subjects with CF. Pseudomonas aeruginosa and Stenotrophomonas maltophilia were isolated in 12% and 5%, respectively, of subjects with CFSPID. CF was diagnosed in 9 of 82 (11%) subjects with CFSPID (genotype and abnormal sweat chloride = 3; genotype alone = 4; abnormal sweat chloride only = 2). Sweat chloride was abnormal in CFSPID→CF patients at a mean (SD) age of 21.3 (13.8) months. CFSPID→CF patients had significantly higher serial sweat chloride (P < .0001) and serum trypsinogen (P = .009) levels than did CFSPID→CFSPID patients. CONCLUSIONS: A proportion of infants with CFSPID will be diagnosed with CF within the first 3 years. These findings underscore the need for clinical monitoring, repeat sweat testing at age 2 to 3 years, and extensive genotyping.

Variants in Solute Carrier SLC26A9 Modify Prenatal Exocrine Pancreatic Damage in Cystic Fibrosis.

OBJECTIVES: To test the hypothesis that multiple constituents of the apical plasma membrane residing alongside the causal cystic fibrosis (CF) transmembrane conductance regulator protein, including known CF modifiers SLC26A9, SLC6A14, and SLC9A3, would be associated with prenatal exocrine pancreatic damage as measured by newborn screened (NBS) immunoreactive trypsinogen (IRT) levels. STUDY DESIGN: NBS IRT measures and genome-wide genotype data were available on 111 subjects from Colorado, 37 subjects from Wisconsin, and 80 subjects from France. Multiple linear regression was used to determine whether any of 8 single nucleotide polymorphisms (SNPs) in SLC26A9, SLC6A14, and SLC9A3 were associated with IRT and whether other constituents of the apical plasma membrane contributed to IRT. RESULTS: In the Colorado sample, 3 SLC26A9 SNPs were associated with NBS IRT (min P=1.16×10(-3); rs7512462), but no SLC6A14 or SLC9A3 SNPs were associated (P>.05). The rs7512462 association replicated in the Wisconsin sample (P=.03) but not in the French sample (P=.76). Furthermore, rs7512462 was the top-ranked apical membrane constituent in the combined Colorado and Wisconsin sample. CONCLUSIONS: NBS IRT is a biomarker of prenatal exocrine pancreatic disease in patients with CF, and a SNP in SLC26A9 accounts for significant IRT variability. This work suggests SLC26A9 as a potential therapeutic target to ameliorate exocrine pancreatic disease.

Pediatric chronic pancreatitis is associated with genetic risk factors and substantial disease burden.

OBJECTIVE: To determine the clinical presentation, diagnostic variables, risk factors, and disease burden in children with chronic pancreatitis. STUDY DESIGN: We performed a cross-sectional study of data from the International Study Group of Pediatric Pancreatitis: In Search for a Cure, a registry of children with acute recurrent pancreatitis and chronic pancreatitis. Between-group differences were compared using Wilcoxon rank-sum test. RESULTS: Among 170 subjects in the registry, 76 (45%) had chronic pancreatitis; 57% were female, 80% were white; median age at diagnosis was 9.9 years. Pancreatitis-predisposing genetic mutations were identified in 51 (67%) and obstructive risk factors in 25 (33%). Toxic/metabolic and autoimmune factors were uncommon. Imaging demonstrated ductal abnormalities and pancreatic atrophy more commonly than calcifications. Fifty-nine (77%) reported abdominal pain within the past year; pain was reported as constant and receiving narcotics in 28%. Children with chronic pancreatitis reported a median of 3 emergency department visits and 2 hospitalizations in the last year. Forty-seven subjects (70%) missed 1 day of school in the past month as the result of chronic pancreatitis; 26 (34%) missed 3 or more days. Children reporting constant pain were more likely to miss school (P = .002), visit the emergency department (P = .01), and experience hospitalizations (P = .03) compared with children with episodic pain. Thirty-three children (43%) underwent therapeutic endoscopic retrograde pancreatography; one or more pancreatic surgeries were performed in 30 (39%). CONCLUSIONS: Chronic pancreatitis occurs at a young age with distinct clinical features. Genetic and obstructive risk factors are common, and disease burden is substantial.

Altered intestinal bile salt biotransformation in a cystic fibrosis (Cftr-/-) mouse model with hepato-biliary pathology.

BACKGROUND: Cftr(-/-tm1Unc) mice develop progressive hepato-biliary pathology. We hypothesize that this liver pathology is related to alterations in biliary bile hydrophobicity and bile salt metabolism in Cftr(-/-tm1Unc) mice. METHODS: We determined bile production, biliary and fecal bile salt- and lipid compositions and fecal bacterial composition of C57BL/6J Cftr(-/-tm1Unc) and control mice. RESULTS: We found no differences between the total biliary bile salt or lipid concentrations of Cftr(-/-) and controls. Compared to controls, Cftr(-/-) mice had a ~30% higher bile production and a low bile hydrophobicity, related to a ~7 fold higher concentration of the choleretic and hydrophilic bile salt ursocholate. These findings coexisted with a significantly smaller quantity of fecal Bacteroides bacteria. CONCLUSIONS: Liver pathology in Cftr(-/-tm1Unc) is not related to increased bile hydrophobicity. Cftr(-/-) mice do however display a biliary phenotype characterized by increased bile production and decreased biliary hydrophobicity. Our findings suggest Cftr dependent, alterations in intestinal bacterial biotransformation of bile salts.

Design and implementation of INSPPIRE.

OBJECTIVES: Acute recurrent pancreatitis (ARP) and chronic pancreatitis (CP) are rare and poorly understood diseases in children. Better understanding of these disorders can only be accomplished via a multicenter, structured, data collection approach. METHODS: The International Study Group of Pediatric Pancreatitis: In Search for a Cure (INSPPIRE) consortium was created to investigate the epidemiology, etiologies, pathogenesis, natural history, and outcomes of pediatric ARP and CP. Patient and physician questionnaires were developed to capture information on demographics, medical history, family and social history, medications, hospitalizations, risk factors, diagnostic evaluation, treatments, and outcome information. Information collected in paper questionnaires was then transferred into Research Electronic Data Capture (REDCap), tabulated, and analyzed. RESULTS: The administrative structure of the INSPPIRE consortium was established, and National Institutes of Health funding was obtained. A total of 14 sites (10 in the United States, 2 in Canada, and 2 overseas) participated. Questionnaires were amended and updated as necessary, followed by changes made into the REDCap database. Between September 1, 2012 and August 31, 2013, a total of 194 children were enrolled into the study: 54% were girls, 82% were non-Hispanic, and 72% were whites. CONCLUSIONS: The INSPPIRE consortium demonstrates the feasibility of building a multicenter patient registry to study the rare pediatric diseases, ARP and CP. Analyses of collected data will provide a greater understanding of pediatric pancreatitis and create opportunities for therapeutic interventional studies that would not otherwise be possible without a multicenter approach.

Evidence for a causal relationship between early exocrine pancreatic disease and cystic fibrosis-related diabetes: a Mendelian randomization study.

Circulating immunoreactive trypsinogen (IRT), a biomarker of exocrine pancreatic disease in cystic fibrosis (CF), is elevated in most CF newborns. In those with severe CF transmembrane conductance regulator (CFTR) genotypes, IRT declines rapidly in the first years of life, reflecting progressive pancreatic damage. Consistent with this progression, a less elevated newborn IRT measure would reflect more severe pancreatic disease, including compromised islet compartments, and potentially increased risk of CF-related diabetes (CFRD). We show in two independent CF populations that a lower newborn IRT estimate is associated with higher CFRD risk among individuals with severe CFTR genotypes, and we provide evidence to support a causal relationship. Increased loge(IRT) at birth was associated with decreased CFRD risk in Canadian and Colorado samples (hazard ratio 0.30 [95% CI 0.15-0.61] and 0.39 [0.18-0.81], respectively). Using Mendelian randomization with the SLC26A9 rs7512462 genotype as an instrumental variable since it is known to be associated with IRT birth levels in the CF population, we provide evidence to support a causal contribution of exocrine pancreatic status on CFRD risk. Our findings suggest CFRD risk could be predicted in early life and that maintained ductal fluid flow in the exocrine pancreas could delay the onset of CFRD.