Identification of CFTR, PRSS1, and SPINK1 mutations in 381 patients with pancreatitis

Cystic Fibrosis Foundation Evidence-Based Guideline for the Management of CRMS/CFSPID

A multidisciplinary committee developed evidence-based guidelines for the management of cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen-positive, inconclusive diagnosis (CRMS/CFSPID). A total of 24 patient, intervention, comparison, and outcome questions were generated based on surveys sent to people with CRMS/CFSPID and clinicians caring for these individuals, previous recommendations, and expert committee input. Four a priori working groups (genetic testing, monitoring, treatment, and psychosocial/communication issues) were used to provide structure to the committee. A systematic review of the evidence was conducted, and found numerous case series and cohort studies, but no randomized clinical trials. A total of 30 recommendations were graded using the US Preventive Services Task Force methodology. Recommendations that received ≥80% consensus among the entire committee were approved. The resulting recommendations were of moderate to low certainty for the majority of the statements because of the low quality of the evidence. Highlights of the recommendations include thorough evaluation with genetic sequencing, deletion/duplication analysis if <2 disease-causing variants were noted in newborn screening; repeat sweat testing until at least age 8 but limiting further laboratory testing, including microbiology, radiology, and pulmonary function testing; minimal use of medications, which when suggested, should lead to shared decision-making with families; and providing communication with emphasis on social determinants of health and shared decision-making to minimize barriers which may affect processing and understanding of this complex designation. Future research will be needed regarding medication use, antibiotic therapy, and the use of chest imaging for monitoring the development of lung disease.

Classification of PRSS1 variants responsible for chronic pancreatitis: An expert perspective from the Franco-Chinese GREPAN study group

BACKGROUND

PRSS1 was the first reported chronic pancreatitis (CP) gene. The existence of both gain-of-function (GoF) and gain-of-proteotoxicity (GoP) pathological PRSS1 variants, together with the fact that PRSS1 variants have been identified in CP subtypes spanning the range from monogenic to multifactorial, has made the classification of PRSS1 variants very challenging.

METHODS

All currently reported PRSS1 variants (derived primarily from two databases) were manually reviewed with respect to their clinical genetics, functional analysis and population allele frequency. They were classified by variant type and pathological mechanism within the framework of our recently proposed ACMG/AMP guidelines-based seven-category system.

RESULTS

The total number of distinct germline PRSS1 variants included for analysis was 100, comprising 3 copy number variants (CNVs), 12 5' and 3' variants, 19 intronic variants, 5 nonsense variants, 1 frameshift deletion variant, 6 synonymous variants, 1 in-frame duplication, 3 gene conversions and 50 missense variants. Based upon a combination of clinical genetic and functional analysis, population data and in silico analysis, we classified 26 variants (all 3 CNVs, the in-frame duplication, all 3 gene conversions and 19 missense) as "pathogenic", 3 variants (missense) as "likely pathogenic", 5 variants (four missense and one promoter) as "predisposing", 13 variants (all missense) as "unknown significance", 2 variants (missense) as "likely benign", and all remaining 51 variants as "benign".

CONCLUSIONS

We describe an expert classification of the 100 PRSS1 variants reported to date. The results have immediate implications for reclassifying many ClinVar-registered PRSS1 variants as well as providing optimal guidelines/standards for reporting PRSS1 variants.

Occam’s razor or Hickam’s dictum-COVID-19 is not a textbook aetiology of acute pancreatitis: A modified Naranjo Score appraisal

BACKGROUND

Acute pancreatitis (AP) is a disease spectrum ranging from mild to severe disease. During the coronavirus disease 2019 (COVID-19) pandemic, numerous reports of AP have been published, with most authors concluding a causal relationship between COVID-19 and AP. Retrospective case reports or small case series are unable to accurately determine the cause-effect relationship between COVID-19 and AP.

AIM

To establish whether COVID-19 is a cause of AP using the modified Naranjo scoring system.

METHODS

A systematic review was conducted on PubMed, World of Science and Embase for articles reporting COVID-19 and AP from inception to August 2021. Exclusion criteria were cases of AP which were not reported to be due to COVID-19 infection, age < 18 years old, review articles and retrospective cohort studies. The original 10-item Naranjo scoring system (total score 13) was devised to approximate the likelihood of a clinical presentation to be secondary to an adverse drug reaction. We modified the original scoring system into a 8-item modified Naranjo scoring system (total score 9) to determine the cause-effect relationship between COVID-19 and AP. A cumulative score was decided for each case presented in the included articles. Interpretation of the modified Naranjo scoring system is as follows: ≤ 3: Doubtful, 4-6: Possible, ≥ 7: Probable cause.

RESULTS

The initial search resulted in 909 articles, with 740 articles after removal of duplicates. A total of 67 articles were included in the final analysis, with 76 patients which had AP reported to be due to COVID-19. The mean age was 47.8 (range 18-94) years. Majority of patients (73.3%) had ≤ 7 d between onset of COVID-19 infection and diagnosis of AP. There were only 45 (59.2%) patients who had adequate investigations to rule out common aetiologies (gallstones, choledocholithiasis, alcohol, hypertriglyceridemia, hypercalcemia and trauma) of AP. Immunoglobulin G4 testing was conducted in 9 (13.5%) patients to rule out autoimmune AP. Only 5 (6.6%) patients underwent endoscopic ultrasound and/or magnetic resonance cholangiopancreatogram to rule out occult microlithiasis, pancreatic malignancy and pancreas divisum. None of the patients had other recently diagnosed viral infections apart from COVID-19 infection, or underwent genetic testing to rule out hereditary AP. There were 32 (42.1%), 39 (51.3%) and 5 (6.6%) patients with doubtful, possible, and probable cause-effect relationship respectively between COVID-19 and AP.

CONCLUSION

Current evidence is weak to establish a strong link between COVID-19 and AP. Investigations should be performed to rule out other causes of AP before establishing COVID-19 as an aetiology.

Rescue of Rare CFTR Trafficking Mutants Highlights a Structural Location-Dependent Pattern for Correction

Cystic Fibrosis (CF) is a genetic disease caused by mutations in the gene encoding the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel. Currently, more than 2100 variants have been identified in the gene, with a large number being very rare. The approval of modulators that act on mutant CFTR protein, correcting its molecular defect and thus alleviating the burden of the disease, revolutionized the field of CF. However, these drugs do not apply to all patients with CF, especially those with rare mutations-for which there is a lack of knowledge on the molecular mechanisms of the disease and the response to modulators. In this work, we evaluated the impact of several rare putative class II mutations on the expression, processing, and response of CFTR to modulators. Novel cell models consisting of bronchial epithelial cell lines expressing CFTR with 14 rare variants were created. The variants studied are localized at Transmembrane Domain 1 (TMD1) or very close to the signature motif of Nucleotide Binding Domain 1 (NBD1). Our data show that all mutations analyzed significantly decrease CFTR processing and while TMD1 mutations respond to modulators, those localized in NBD1 do not. Molecular modeling calculations confirm that the mutations in NBD1 induce greater destabilization of CFTR structure than those in TMD1. Furthermore, the structural proximity of TMD1 mutants to the reported binding site of CFTR modulators such as VX-809 and VX-661, make them more efficient in stabilizing the CFTR mutants analyzed. Overall, our data suggest a pattern for mutation location and impact in response to modulators that correlates with the global effect of the mutations on CFTR structure.

Diagnosis, severity stratification and management of adult acute pancreatitis-current evidence and controversies

Acute pancreatitis (AP) is a disease spectrum ranging from mild to severe with an unpredictable natural course. Majority of cases (80%) are mild and self-limiting. However, severe AP (SAP) has a mortality risk of up to 30%. Establishing aetiology and risk stratification are essential pillars of clinical care. Idiopathic AP is a diagnosis of exclusion which should only be used after extended investigations fail to identify a cause. Tenets of management of mild AP include pain control and management of aetiology to prevent recurrence. In SAP, patients should be resuscitated with goal-directed fluid therapy using crystalloids and admitted to critical care unit. Routine prophylactic antibiotics have limited clinical benefit and should not be given in SAP. Patients able to tolerate oral intake should be given early enteral nutrition rather than nil by mouth or parenteral nutrition. If unable to tolerate per-orally, nasogastric feeding may be attempted and routine post-pyloric feeding has limited evidence of clinical benefit. Endoscopic retrograde cholangiopancreatogram should be selectively performed in patients with biliary obstruction or suspicion of acute cholangitis. Delayed step-up strategy including percutaneous retroperitoneal drainage, endoscopic debridement, or minimal-access necrosectomy are sufficient in most SAP patients. Patients should be monitored for diabetes mellitus and pseudocyst.

WITHDRAWN: Clinical interpretation of PRSS1 gene variants in patients with pancreatitis

The Publisher regrets that this article is an accidental duplication of an article that has already been published in Clinics and Research in Hepatology and Gastroenterology, Volume 45, Issue 1, 2021, 101497. https://doi.org/10.1016/j.clinre.2020.07.004. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal

Probability of high-risk genetic matching with oocyte and semen donors: complete gene analysis or genotyping test?

PURPOSE

To estimate the probability of high-risk genetic matching when assisted reproductive techniques (ART) are applied with double gamete donation, following an NGS carrier test based on a complete study of the genes concerned. We then determine the results that would have been obtained if the genotyping tests most widely used in Spanish gamete banks had been applied.

METHODS

In this descriptive observational study, 1818 gamete donors were characterised by NGS. The pathogenic variants detected were analysed to estimate the probability of high-risk genetic matching and to determine the results that would have been obtained if the three most commonly used genotyping tests in ART had been applied.

RESULTS

The probability of high-risk genetic matching with gamete donation, screened by NGS and complete gene analysis, was 5.5%, versus the 0.6-2.7% that would have been obtained with the genotyping test. A total of 1741 variants were detected, including 607 different variants, of which only 22.6% would have been detected by all three genotyping tests considered and 44.7% of which would not have been detected by any of these tests.

CONCLUSION

Our study highlights the considerable heterogeneity of the genotyping tests, which present significant differences in their ability to detect pathogenic variants. The complete study of the genes by NGS considerably reduces reproductive risks when genetic matching is performed with gamete donors. Accordingly, we recommend that carrier screening in gamete donors be carried out using NGS and a complete study with nontargeted analysis of the variants of the screened genes.

Clinical interpretation of PRSS1 variants in patients with pancreatitis

Since the description of the PRSS1 gene encoding the cationic trypsinogen as being involved in dominant hereditary pancreatitis, more than 50 PRSS1 variants have been reported. Among the PRSS1 variants that have been classified as pathogenic, some have a high penetrance and others have a low penetrance. Assessing the clinical relevance of PRSS1 variants is often complicated in the absence of functional evidence and interpretation of rare variants is not very easy in clinical practice. The aim of this study was to review the different variants identified in the PRSS1 gene and to classify them according to their degree of deleterious effect. This classification was based on the results of several in vitro experiments and on population data, in comparing the allelic frequency of each variant in patients with pancreatitis and in unaffected individuals. This review should help geneticists and clinicians in charge of patient's care and genetic counseling to interpret molecular results.

Clinical interpretation of SPINK1 and CTRC variants in pancreatitis

Since the description of the SPINK1 gene encoding the serine protease inhibitor Kazal type 1 and the CTRC gene encoding the Chymotrypsin C as being involved in chronic pancreatitis, more than 56 SPINK1 and 87 CTRC variants have been reported. Assessing the clinical relevance of SPINK1 and CTRC variants is often complicated in the absence of functional evidence and interpretation of rare variants is not very easy in clinical practice. The aim of this study was to review the different variants identified in these two genes and to classify them according to their degree of damaging effect. This classification was based on the results of in vitro experiments, in silico analysis using different prediction tools, and on population data, in comparing the allelic frequency of each variant in patients with pancreatitis and in unaffected control individuals. This review should help geneticists and clinicians in charge of patient's care and genetic counseling to interpret the results of genetic studies.

Carriers of cystic fibrosis among sperm donors: complete CFTR gene analysis versus CFTR genotyping

OBJECTIVE

To determine the frequency of cystic fibrosis (CF) carriers among sperm donors in Spain studied through a complete analysis of the CFTR gene and to compare the results with those that would have been obtained by the 4 genotyping panels of the CFTR gene most commonly used as a carrier test in the context of assisted reproduction in our country.

DESIGN

Descriptive observational study.

SETTING

Private center.

PATIENTS

Nine hundred thirty-five sperm donors, from January 2014 to June 2019.

INTERVENTION

None.

MAIN OUTCOME MEASURE

Presence of pathogenic variants in the CFTR gene.

RESULTS

17% of the donors were carriers of at least 1 pathogenic variant in CFTR, with 39 different pathogenic variants detected. Only 4 of these 39 variants (10.27%) would have been detected by the 4 genotyping tests considered, and 22 variants (56.41%) would not have been detected by any of the genotyping tests. The pathogenic variants of the CFTR gene included in the different genotyping tests analyzed vary widely, and <50% are common to all of them.

CONCLUSIONS

Although the was not based in the general population, these results show that the use of genotyping tests is associated with a high reproductive risk, because the rate of detection of CF carriers was lower when these panels were applied, in comparison with the complete study of the CFTR gene. We recommend that complete sequencing of the CFTR gene by next-generation sequencing be performed as a screening method for CF in sperm donors.

The Cystic Fibrosis Transmembrane Conductance Regulator 470 Met Allele Is Associated with an Increased Risk of Chronic Pancreatitis in Both Asian and Caucasian Populations: A Meta-Analysis

Background: The Met470Val polymorphism (1540A>G [rs213950]) within the cystic fibrosis transmembrane conductance regulator (CFTR) protein has been reported to be associated with chronic pancreatitis (CP). The results remain inconclusive, and therefore, we performed this meta-analysis to clarify the association between M470V and CP risk. Methodology/Results: We conducted a meta-analysis of 7 case-control studies, including a total of 1121 CP patients and 2209 controls from Asian and Caucasian populations. We calculated the odds ratio (OR) and 95% confidence intervals (95% CI). Met470Val was found to be significantly associated with an increased risk of CP under all the genetic models (M vs. V, OR = 1.260, 95% CI: 1.134-1.399; MV vs. VV, OR = 1.292, 95% CI: 1.091-1.530; MM vs. VV, OR = 1.579, 95% CI: 1.274-1.956; MV/MV vs. VV, OR = 1.366, 95% CI: 1.165-1.603; MM vs. MV/VV, OR = 1.346, 95% CI: 1.114-1.621). Met470Val was also found to be significantly associated with an increased risk of idiopathic CP (ICP) in allele contrast, codominant, and recessive models (M vs. V, OR = 1.298, 95% CI: 1.020-1.653; MV vs. VV, OR = 1.297, 95% CI: 1.074-1.566; MM vs. VV, OR = 1.473, 95% CI: 1.165-1.862; MM vs. MV/VV, OR = 1.254, 95% CI: 1.023-1.538). Conclusions: The CFTR 470 M allele is significantly associated with an increased risk of CP in both Asian and Caucasian populations. The CFTR 470 M allele is also significantly associated with risk of ICP.

Surface loops of trypsin-like serine proteases as determinants of function

Trypsin and chymotrypsin-like serine proteases from family S1 (clan PA) constitute the largest protease group in humans and more generally in vertebrates. The prototypes chymotrypsin, trypsin and elastase represent simple digestive proteases in the gut, where they cleave nearly any protein. Multidomain trypsin-like proteases are key players in the tightly controlled blood coagulation and complement systems, as well as related proteases that are secreted from diverse immune cells. Some serine proteases are expressed in nearly all tissues and fluids of the human body, such as the human kallikreins and kallikrein-related peptidases with specialization for often unique substrates and accurate timing of activity. HtrA and membrane-anchored serine proteases fulfill important physiological tasks with emerging roles in cancer. The high diversity of all family members, which share the tandem β-barrel architecture of the chymotrypsin-fold in the catalytic domain, is conferred by the large differences of eight surface loops, surrounding the active site. The length of these loops alters with insertions and deletions, resulting in remarkably different three-dimensional arrangements. In addition, metal binding sites for Na+, Ca2+ and Zn2+ serve as regulatory elements, as do N-glycosylation sites. Depending on the individual tasks of the protease, the surface loops determine substrate specificity, control the turnover and allow regulation of activation, activity and degradation by other proteins, which are often serine proteases themselves. Most intriguingly, in some serine proteases, the surface loops interact as allosteric network, partially tuned by protein co-factors. Knowledge of these subtle and complicated molecular motions may allow nowadays for new and specific pharmaceutical or medical approaches.

Referral frequency, attrition rate, and outcomes of germline testing in patients with pancreatic adenocarcinoma

Hereditary predisposition is estimated to account for 10% of all pancreatic cancer cases. However, referral patterns and clinical workflow for germline testing in this disease differ significantly by institution, and many at-risk patients may not undergo appropriate counseling and testing. We undertook an analysis of patients diagnosed with pancreatic cancer (PDAC) who were referred to the Clinical Genetics program of a high-volume academic center over a 3-year period to assess referral frequency, evaluate the yield of germline testing in this selected patient cohort, and elucidate the reasons individuals did not undergo recommended germline testing. Medical records of patients with PDAC referred for genetic counseling between January 2015 and October 2017 were reviewed for demographic, medical/family history, and disease-specific data. If testing did not occur, reasons were documented. Genetic test results were categorized as negative, variants of unknown significance, or established pathogenic mutations. Descriptive statistics included means with standard deviations; associations were analyzed with t test and Fisher's exact test. 32% (137 of 432) of PDAC patients were referred for genetic counseling, but only 64% attended their appointment and 60% ultimately underwent germline testing. Common reasons for attrition included worsening disease severity, lack of patient follow-up, insurance concerns, and logistic/travel challenges. Pathogenic germline mutations were detected in 20% (16 of 82) of patients tested, distributed across races/ethnicities, and significantly associated with younger age and positive family history of breast cancer. PDAC patients frequently do not undergo genetic counseling/germline testing despite appropriate referrals, highlighting a need to develop streamlined processes to engage more patients in testing, especially those with high-risk features.

Early Intra-Acinar Events in Pathogenesis of Pancreatitis

Premature activation of digestive enzymes in the pancreas has been linked to development of pancreatitis for more than a century. Recent development of novel models to study the role of pathologic enzyme activation has led to advances in our understanding of the mechanisms of pancreatic injury. Colocalization of zymogen and lysosomal fraction occurs early after pancreatitis-causing stimulus. Cathepsin B activates trypsinogen in these colocalized organelles. Active trypsin increases permeability of these organelles resulting in leakage of cathepsin B into the cytosol leading to acinar cell death. Although trypsin-mediated cell death leads to pancreatic injury in early stages of pancreatitis, multiple parallel mechanisms, including activation of inflammatory cascades, endoplasmic reticulum stress, autophagy, and mitochondrial dysfunction in the acinar cells are now recognized to be important in driving the profound systemic inflammatory response and extensive pancreatic injury seen in acute pancreatitis. Chymotrypsin, another acinar protease, has recently been shown be play critical role in clearance of pathologically activated trypsin protecting against pancreatic injury. Mutations in trypsin and other genes thought to be associated with pathologic enzyme activation (such as serine protease inhibitor 1) have been found in familial forms of pancreatitis. Sustained intra-acinar activation of nuclear factor κB pathway seems to be key pathogenic mechanism in chronic pancreatitis. Better understanding of these mechanisms will hopefully allow us to improve treatment strategies in acute and chronic pancreatitis.

Genetic predisposition in pancreatitis

PURPOSE OF REVIEW

Genetic mutations are the primary cause for acute recurrent (ARP) and chronic pancreatitis in children. Further, our medical approach for many diseases is changing from a one-drug therapy to more individualized therapeutic strategies. In respect to the therapeutic management of ARP/chronic pancreatitis, this entails an understanding of the individual, mainly genetic, risk factors that led to pancreatitis disease.

RECENT FINDINGS

New pancreatitis-associated genes are continuously emerging from increasingly large genetic cohort studies. Furthermore, newer research findings demonstrate that multiple genetic and nongenetic factors are required to increase the individual risk for developing ARP/chronic pancreatitis. Last, there is new exciting development towards targeted pancreatitis therapy in the future.

SUMMARY

This review introduces the current concept of ARP/chronic pancreatitis as a complex disease caused by multiple genetic and nongenetic factors. This warrants careful evaluation of these patients and ideally consultation of a pancreas expert to help understand individual genetic risk profiles and to provide more effective patient consultation.

Trans-heterozygosity for mutations enhances the risk of recurrent/chronic pancreatitis in patients with Cystic Fibrosis

BACKGROUND

Recurrent (RP) and chronic pancreatitis (CP) may complicate Cystic Fibrosis (CF). It is still unknown if mutations in genes involved in the intrapancreatic activation of trypsin (IPAT) or in the pancreatic secretion pathway (PSP) may enhance the risk for RP/CP in patients with CF.

METHODS

We enrolled: 48 patients affected by CF complicated by RP/CP and, as controls 35 patients with CF without pancreatitis and 80 unrelated healthy subjects. We tested a panel of 8 genes involved in the IPAT, i.e. PRSS1, PRSS2, SPINK1, CTRC, CASR, CFTR, CTSB and KRT8 and 23 additional genes implicated in the PSP.

RESULTS

We found 14/48 patients (29.2%) with mutations in genes involved in IPAT in the group of CF patients with RP/CP, while mutations in such genes were found in 2/35 (5.7%) patients with CF without pancreatitis and in 3/80 (3.8%) healthy subjects (p < 0.001). Thus, we found mutations in 12 genes of the PSP in 11/48 (22.9%) patients with CF and RP/CP. Overall, 19/48 (39.6%) patients with CF and RP/CP showed one or more mutations in the genes involved in the IPAT and in the PSP while such figure was 4/35 (11.4%) for patients with CF without pancreatitis and 11/80 (13.7%) for healthy controls (p < 0.001).

CONCLUSIONS

The trans-heterozygous association between CFTR mutations in genes involved in the pathways of pancreatic enzyme activation and the pancreatic secretion may be risk factors for the development of recurrent or chronic pancreatitis in patients with CF.

Total Pancreatectomy With Intraportal Islet Autotransplantation as a Treatment of Chronic Pancreatitis in Patients With CFTR Mutations

OBJECTIVES

Chronic pancreatitis (CP) is an infrequent but debilitating complication associated with CFTR mutations. Total pancreatectomy with islet autotransplantation (TPIAT) is a treatment option for CP that provides pain relief and preserves β-cell mass, thereby minimizing the complication of diabetes mellitus. We compared outcomes after TPIAT for CP associated with CFTR mutations to CP without CTFR mutations.

METHODS

All TPIATs performed between 2002 and 2014 were retrospectively reviewed: identifying 20 CFTR homozygotes (cystic fibrosis [CF] patients), 19 CFTR heterozygotes, and 20 age-/sex-matched controls without CFTR mutations. Analysis of variance and χ tests were used to compare groups.

RESULTS

Baseline demographics were not different between groups. Postoperative glycosylated hemoglobin and C-peptide levels were similar between groups, as were islet yield and rate of postoperative complications. At 1 year, 40% of CF patients, 22% of CFTR heterozygotes, and 35% of control patients were insulin independent.

CONCLUSION

Total pancreatectomy with islet autotransplantation is a safe, effective treatment option for CF patients with CP, giving similar outcomes for those with other CP etiologies.

The Differential Role of Human Cationic Trypsinogen (PRSS1) p.R122H Mutation in Hereditary and Nonhereditary Chronic Pancreatitis: A Systematic Review and Meta-Analysis

Background

Environmental factors and genetic mutations have been increasingly recognized as risk factors for chronic pancreatitis (CP). The PRSS1 p.R122H mutation was the first discovered to affect hereditary CP, with 80% penetrance. We performed here a systematic review and meta-analysis to evaluate the associations of PRSS1 p.R122H mutation with CP of diverse etiology.

Methods

The PubMed, EMBASE, and MEDLINE database were reviewed. The pooled odds ratio (OR) with 95% confidence intervals was used to evaluate the association of p.R122H mutation with CP. Initial analysis was conducted with all etiologies of CP, followed by a subgroup analysis for hereditary and nonhereditary CP, including alcoholic or idiopathic CP.

Results

A total of eight case-control studies (1733 cases and 2415 controls) were identified and included. Overall, PRSS1 p.R122H mutation was significantly associated with an increased risk of CP (OR = 4.78[1.13-20.20]). Further analysis showed p.R122H mutation strongly associated with the increased risk of hereditary CP (OR = 65.52[9.09-472.48]) but not with nonhereditary CP, both alcoholic and idiopathic CP.

Conclusions

Our study showing the differential role of p.R122H mutation in various etiologies of CP indicates that this complex disorder is likely influenced by multiple genetic factors as well as environmental factors.

Genetic risk in chronic pancreatitis: the misfolding-dependent pathway

PURPOSE OF REVIEW

Genetic risk in chronic pancreatitis is partly due to mutations that cause misfolding of digestive enzymes and elicit endoplasmic reticulum stress. This review examines recent developments in this concept.

RECENT FINDINGS

The best characterized misfolding variants in the highly expressed digestive proteases cationic trypsinogen (PRSS1) and carboxypeptidase A1 (CPA1) are strong, causative risk factors for chronic pancreatitis and may be associated with autosomal dominant hereditary pancreatitis.

SUMMARY

Properties of misfolding digestive enzyme mutants indicate that endoplasmic reticulum stress is a highly relevant pathological mechanism and a potential therapeutic target in chronic pancreatitis.

Genetic Risk in Chronic Pancreatitis: The Trypsin-Dependent Pathway

Genetic investigations have provided unique insight into the mechanism of chronic pancreatitis in humans and firmly established that uncontrolled trypsin activity is a central pathogenic factor. Mutations in the PRSS1, SPINK1, and CTRC genes promote increased activation of trypsinogen to trypsin by stimulation of autoactivation or by impairing protective trypsinogen degradation and/or trypsin inhibition. Here we review key genetic and biochemical features of the trypsin-dependent pathological pathway in chronic pancreatitis.

PRSS1, SPINK1, CFTR, and CTRC Pathogenic Variants in Korean Patients With Idiopathic Pancreatitis

BACKGROUND

This study aimed to identify pathogenic variants of PRSS1, SPINK1, CFTR, and CTRC genes in Korean patients with idiopathic pancreatitis.

METHODS

The study population consisted of 116 Korean subjects (65 males, 51 females; mean age, 30.4 yr, range, 1-88 yr) diagnosed with idiopathic chronic pancreatitis (ICP), idiopathic recurrent acute pancreatitis (IRAP), or idiopathic acute pancreatitis (IAP). We analyzed sequences of targeted regions in the PRSS1, SPINK1, CFTR, and CTRC genes, copy numbers of PRSS1 and SPINK1, and clinical data from medical records.

RESULTS

We identified three types of pathogenic PRSS1 variants in 11 patients, including p.N29I (n=1), p.R122H (n=1), and p.G208A (n=9). Sixteen patients exhibited heterozygous pathogenic variants of SPINK1, including c.194+2T>C (n=12), p.N34S (n=3), and a novel pathogenic splicing variation c.194+1G>A. A heterozygous CFTR p.Q1352H pathogenic variant was detected in eight patients. One patient carried a heterozygous CTRC p.P249L pathogenic variant, which is a known high-risk variant for pancreatitis. All patients had normal PRSS1 and SPINK1 gene copy numbers. Weight loss occurred more frequently in patients carrying the p.G208A pathogenic variant, while pancreatic duct stones occurred more frequently in patients with the c.194+2T>C pathogenic variant.

CONCLUSIONS

Pathogenic variants of PRSS1, SPINK1, and CFTR were associated with idiopathic pancreatitis, while pathogenic variants of CTRC were not. Copy number variations of PRSS1 and SPINK1 were not detected.

Pancreatic duct stenosis: Differential diagnosis between malignant and benign conditions at secretin-enhanced MRCP

PURPOSE

To define imaging criteria of benign and malignant nature in patients with main pancreatic duct (MPD) stenosis.

MATERIALS-METHODS

S-MRCPs of 35 patients with pancreatitis and 14 with adenocarcinoma were evaluated.

RESULTS

Adenocarcinoma caused higher prevalence of complete stenosis (14/14-100% vs 17/35-49%), dilated side-branches (14/14-100% vs 18/35-51%) and lower prevalence of duct-penetrating sign (0/14-0% vs 31/35-89%). The number of stenoses was higher in benign conditions (mean 1.4 Vs 1). Upstream MPD diameter was higher in cancer-induced stenoses (4.5 vs 2.9mm).

CONCLUSIONS

Single complete stenosis with dilated side branches, increased MPD caliber and absent duct-penetrating sign are suggestive of malignancy.

Genetic Analysis of Japanese Children With Acute Recurrent and Chronic Pancreatitis

OBJECTIVES

Causes of acute recurrent pancreatitis (ARP) or chronic pancreatitis (CP) are sometimes difficult to determine in children. In such patients, genetic analysis may prove helpful. The present study analyzed mutations of cationic trypsinogen (PRSS1), serine protease inhibitor Kazal type 1 (SPINK1), chymotrypsin C (CTRC), and carboxypeptidase A1 (CPA1) and investigated the clinical features of children with these mutations.

METHODS

Genetic analyses of mutations in these 4 genes were conducted in 128 patients with ARP or CP. Characteristics of the patients showing mutations were investigated using medical records.

RESULTS

Fifty of the 128 (39.1%) subjects had at least 1 mutation (median age at onset, 7.6 years). Abdominal pain was the presenting symptom of pancreatitis in 48 of the 50 patients (96%). Fifteen of those 50 patients (30.0%) had a family history of pancreatitis. Gene mutations were present in PRSS1 in 26 patients, SPINK1 in 23, CTRC in 3, and CPA1 in 5. In the 31 patients with mutations in SPINK1, CTRC, or CPA1, 16 (51.6%) had homozygous or heterozygous mutations with other mutations. Three patients underwent surgery and another 4 patients underwent endoscopy to manage ARP or CP. Although 3 of the 7 patients complained of mild abdominal pain, none of those 7 patients experienced any obvious episode of ARP after treatment.

CONCLUSIONS

In pediatric patients with idiopathic ARP and CP, genetic analysis is useful for identifying the cause of pancreatitis. Early endoscopic or surgical treatment prevents ARP by extending the interval between episodes of pancreatitis in this population.

Genetic Mutations in Pediatric Pancreatitis

OBJECTIVES

The aim of our study was to describe the prevalence, characteristics, and outcomes of children with acute recurrent (ARP) or chronic (CP) pancreatitis with or without mutations in PRSS1, CFTR or SPINK1.

METHODS

Retrospective chart review of children with ARP or CP with and without testing for PRSS1, CFTR, and SPINK1. Demographics, clinical features, management, and outcome were collected. Analysis of variance was used to compare continuous variables and χ or Fisher exact test for categorical variables.

RESULTS

Ninety-one subjects with ARP (n = 77) or CP (n = 14) were identified and included in this study. Of these, 37 (41%) were male, 44 were white, and 30 were Hispanic. Thirty-three (36%) had at least 1 mutation identified (Pan-Mut): PRSS1 (7), CFTR (21), SPINK1 (3), SPINK/CFTR (2). Thirty-six were tested but had no mutation, and 22 were not tested. The Pan-Mut subjects were more likely to have a family history of pancreatitis but there were no differences in the clinical features, imaging or outcome.

CONCLUSIONS

Mutations in CFTR, SPINK1 or PRSS1 are present in one third of pediatric ARP and CP with no other cause. No clinical features or outcomes differentiated between the Pan-Mut group and the no-mutation group. The Pan-Mut subjects were more likely to have a family history of pancreatitis. Pediatric ARP and CP without identified cause should undergo genetic testing.

SPINK1 Promoter Variants in Chronic Pancreatitis

OBJECTIVES

Serine protease inhibitor Kazal type 1 (SPINK1) provides an important line of defense against premature trypsinogen activation within the pancreas. Our aim was to identify pathogenic SPINK1 promoter variants associated with chronic pancreatitis (CP).

METHODS

One hundred CP patients (cases) and 100 controls with no pancreatic disease from the Hungarian National Pancreas Registry were enrolled. Direct sequencing of SPINK1 promoter region was performed. Functional characterization of variants was carried out using luciferase reporter gene assay.

RESULTS

Two common polymorphisms (c.-253T>C and c.-807C>T) were found in both cases and controls. Variant c.253T>C was enriched in cases relative to controls (odds ratio, 2.1; 95% confidence interval, 1.2-3.8; P = 0.015). Variant c.-215G>A was detected in 3 of 100 cases; always linked with the pathogenic variant c.194+2T>C. Novel promoter variants c.-14G>A, c.-108G>T, and c.-246A>G were identified in 1 case each. Functional analysis showed decreased promoter activity for variants c.-14G>A (80%), c.-108G>T (31%), and c.-246A>G (47%) whereas activity of variant c.-215G>A was increased (201%) and variant c.-253T>C was unchanged compared with wild type.

CONCLUSIONS

The common promoter variant c.-253T>C was associated with CP in this cohort. Two of 3 newly identified SPINK1 promoter variants seem to exhibit significant functional defects and should be considered potential risk factors for CP.

Spontaneous Pancreatitis Caused by Tissue-Specific Gene Ablation of Hhex in Mice

BACKGROUND & AIMS

Perturbations in pancreatic ductal bicarbonate secretion cause chronic pancreatitis. The physiologic mechanism of ductal secretion is known, but its transcriptional control is not. We determine the role of the transcription factor hematopoietically expressed homeobox protein (Hhex) in ductal secretion and pancreatitis.

METHODS

We derived mice with pancreas-specific, Cremediated Hhex gene ablation to determine the requirement of Hhex in the pancreatic duct in early life and in adult stages. Histologic and immunostaining analyses were used to detect the presence of pathology. Pancreatic primary ductal cells were isolated to discover differentially expressed transcripts upon acute Hhex ablation on a cell autonomous level.

RESULTS

Hhex protein was detected throughout the embryonic and adult ductal trees. Ablation of Hhex in pancreatic progenitors resulted in postnatal ductal ectasia associated with acinar-to-ductal metaplasia, a progressive phenotype that ultimately resulted in chronic pancreatitis. Hhex ablation in adult mice, however, did not cause any detectable pathology. Ductal ectasia in young mice did not result from perturbation of expression of Hnf6, Hnf1β, or the primary cilia genes. RNA-seq analysis of Hhex-ablated pancreatic primary ductal cells showed mRNA levels of the G-protein coupled receptor natriuretic peptide receptor 3 (Npr3), implicated in paracrine signaling, up-regulated by 4.70-fold.

CONCLUSIONS

Although Hhex is dispensable for ductal cell function in the adult, ablation of Hhex in pancreatic progenitors results in pancreatitis. Our data highlight the critical role of Hhex in maintaining ductal homeostasis in early life and support ductal hypersecretion as a novel etiology of pediatric chronic pancreatitis.

Functional significance of SPINK1 promoter variants in chronic pancreatitis

Chronic pancreatitis is a progressive inflammatory disorder of the pancreas, which often develops as a result of genetic predisposition. Some of the most frequently identified risk factors affect the serine protease inhibitor Kazal type 1 (SPINK1) gene, which encodes a trypsin inhibitor responsible for protecting the pancreas from premature trypsinogen activation. Recent genetic and functional studies indicated that promoter variants in the SPINK1 gene might contribute to disease risk in carriers. Here, we investigated the functional effects of 17 SPINK1 promoter variants using luciferase reporter gene expression assay in four different cell lines, including three pancreatic acinar cell lines (rat AR42J with or without dexamethasone-induced differentiation and mouse 266-6) and human embryonic kidney 293T cells. We found that most variants caused relatively small changes in promoter activity. Surprisingly, however, we observed significant variations in the effects of the promoter variants in the different cell lines. Only four variants exhibited consistently reduced promoter activity in all acinar cell lines, confirming previous reports that variants c.-108G>T, c.-142T>C, and c.-147A>G are risk factors for chronic pancreatitis and identifying c.-52G>T as a novel risk variant. In contrast, variant c.-215G>A, which is linked with the disease-associated splice-site mutation c.194 + 2T>C, caused increased promoter activity, which may mitigate the overall effect of the pathogenic haplotype. Our study lends further support to the notion that sequence evaluation of the SPINK1 promoter region in patients with chronic pancreatitis is justified as part of the etiological investigation.

Genetic and electrophysiological characteristics of recurrent acute pancreatitis

OBJECTIVES

The aim was to present the workup of patients with acute recurrent pancreatitis (ARP) for genetic analysis and electrophysiological testing.

METHODS

Patients with ARP with unknown etiology were referred for genetic testing and evaluation of cystic fibrosis transmembrane conductor regulator (CFTR) function by nasal potential difference (NPD) testing.

RESULTS

A total of 67 patients were evaluated. The mean age was 23 ± 17 years (median 17.0 years, range 1.5-72 years); 90% were Jewish and 10% Arab. Ten (15%) patients carried PRSS1 gene mutation (K23R(7), R122H(2), and D21A(1)). One patient had K172E/- (chymotrypsin C [CTRC]) mutation, 1 had I42M (serine protease inhibitor Kazal type 1 [SPINK1])/V235I (CTRC) together with ΔF508/5T, 1 patient had R67H (SPINK1)/V235I (CTRC), and 1 patient had V235I (CTRC)/-. Ten of 67 (15%) patients submitted for CFTR gene testing carried mutations (ΔF508/L997F, ΔF508/5T(11TG), W1282/5T(12TG), W1282X/Y1014C, ΔF508/R31C, R117H/-, R117H/Y1014C, D1152H/-, 5T(11TG)/-, and L997F/-). Fifty-four (80%) patients underwent sweat testing. Of these, 5 had sweat chloride ≥60 mEq/L, and 22 patients had sweat chloride from 40 to 60 mEq/L. Of the 56 (83%) patients had nasal potential difference testing, 4 (6%) with abnormal results.

CONCLUSIONS

One-third (34%) of patients with ARP carry mutations for hereditary pancreatitis including rare mutations (K23R), and 12.5% have evidence of cftr mutations and 10% had CFTR dysfunction underscoring the importance of genetic and functional workup of these patients.

Evaluating Adults With Idiopathic Pancreatitis for Genetic Predisposition: Higher Prevalence of Abnormal Results With Use of Complete Gene Sequencing

OBJECTIVES

In adults with unexplained pancreatitis, the yield of complete gene versus select exosome sequencing on mutation detection and distinguishing clinical characteristics associated with mutations requires clarification. We sought to (1) compare frequency of mutations identified using different techniques and (2) compare clinical characteristics between adults with and without mutations.

METHODS

This is a cohort study of adults with unexplained pancreatitis who underwent genetic testing between January 2008 and December 2012. We compare probabilities of having a positive mutation with complete gene sequencing versus alternatives and describe differences in characteristics among patients with and without mutations.

RESULTS

Of the 370 patients, 67 (18%) had a genetic mutation; 24 (6%) were of high risk. Mutations were significantly more prevalent with use of complete sequencing (42%) versus other approaches (8%, P < 0.0001). Most (44/67, 66%) with a mutation had no family history. Those with high-risk mutations were more likely to have a family history of chronic pancreatitis (21% vs 4%, P = 0.002). Patients with pancreas divisum were more likely to have mutations (27% vs 14%, P = 0.0007).

CONCLUSION

Among individuals with adult-onset pancreatic disease, the probability of finding any mutation, including high risk, is significantly higher using complete gene sequencing. The impact on patients and providers requires further investigation.

Genetics of pancreatitis: the 2014 update

Chronic pancreatitis is a progressive inflammatory disease in which pancreatic secretory parenchyma is destroyed and replaced by fibrous tissue, eventually leading to malnutrition and diabetes. Alcohol is the leading cause in Western countries, but genetic factors are also implicated. Since the identification of mutations in the cationic trypsinogen (PRSS1) gene as a cause of hereditary pancreatitis in 1996, we have seen great progress in our understanding of the genetics of pancreatitis. It has been established that mutations in the genes related to the activation and inactivation of trypsin(ogen) such as PRSS1, serine protease inhibitor Kazal type 1 (SPINK1) and chymotrypsin C (CTRC) genes are associated with pancreatitis. In 2013, carboxypeptidase A1 (CPA1) was identified as a novel pancreatitis susceptibility gene. Endoplasmic reticulum stress in pancreatic acinar cells resulting from the mis-folding of mutated pancreatic enzymes has been shown to act as a novel mechanism underlying the susceptibility to pancreatitis. In Japan, the nationwide survey revealed 171 patients (96 males and 75 females) with hereditary pancreatitis in 59 families based on the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer criteria. Because about 30% of families with hereditary pancreatitis do not carry mutations in any of the known pancreatitis susceptibility genes, other yet unidentified genes might be involved. Next generation sequencers can perform billions of sequencing reactions with a read length of 150-250 nucleotides. Comprehensive analysis using next generation sequencers will be a promising strategy to identify novel pancreatitis-associated genes and further clarify the pathogenesis of pancreatitis.

Human cationic trypsinogen (PRSS1) variants and chronic pancreatitis

Variations in the serine protease 1 (PRSS1) gene encoding human cationic trypsinogen have been conclusively associated with autosomal dominant hereditary pancreatitis and sporadic nonalcoholic chronic pancreatitis. Most high-penetrance PRSS1 variants increase intrapancreatic trypsin activity by stimulating trypsinogen autoactivation and/or by inhibiting chymotrypsin C-dependent trypsinogen degradation. Alternatively, some PRSS1 variants can cause trypsinogen misfolding, which results in intracellular retention and degradation with consequent endoplasmic reticulum stress. However, not all PRSS1 variants are pathogenic, and clinical relevance of rare variants is often difficult to ascertain. Here we review the PRSS1 variants published since 1996 and discuss their functional properties and role in chronic pancreatitis.

Functional effects of 13 rare PRSS1 variants presumed to cause chronic pancreatitis

OBJECTIVE

Hereditary pancreatitis is caused by mutations in human cationic trypsinogen (PRSS1) which lead to increased autoactivation by altering chymotrypsin C (CTRC)-dependent trypsinogen activation and degradation. Exceptions are some cysteine mutations which cause misfolding, intracellular retention and endoplasmic reticulum stress. Clinical relevance of many PRSS1 variants found in patients with sporadic chronic pancreatitis is unknown but often assumed by analogy with known disease-causing mutations. Functional comparison of PRSS1 variants found in sporadic and hereditary cases is needed to resolve this dilemma.

DESIGN

Here, we investigated the functional phenotype of 13 published PRSS1 variants with respect to autoactivation in the presence of CTRC and cellular secretion.

RESULTS

Only mutation p.D100H increased trypsinogen autoactivation, but this gain in function was offset by a marked reduction in secretion. Five mutants (p.P36R, p.G83E, p.I88N, p.V123M, p.S124F) showed decreased autoactivation due to increased degradation by CTRC. Five mutants exhibited strongly (p.D100H, p.C139F) or moderately (p.K92N, p.S124F, p.G208A) reduced secretion, whereas mutant p.K170E showed slightly increased secretion. Mutant p.I88N was also secreted to higher levels but was rapidly degraded by CTRC. Finally, three mutants (p.Q98K, p.T137M, p.S181G) had no phenotypic alterations relative to wild-type trypsinogen.

CONCLUSIONS

Rare PRSS1 variants found in sporadic chronic pancreatitis do not stimulate autoactivation but may cause increased degradation, impaired secretion or no functional change. Variants with reduced secretion are likely pathogenic due to mutation-induced misfolding and consequent endoplasmic reticulum stress.

A conservative assessment of the major genetic causes of idiopathic chronic pancreatitis: data from a comprehensive analysis of PRSS1, SPINK1, CTRC and CFTR genes in 253 young French patients

Idiopathic chronic pancreatitis (ICP) has traditionally been defined as chronic pancreatitis in the absence of any obvious precipitating factors (e.g. alcohol abuse) and family history of the disease. Studies over the past 15 years have revealed that ICP has a highly complex genetic architecture involving multiple gene loci. Here, we have attempted to provide a conservative assessment of the major genetic causes of ICP in a sample of 253 young French ICP patients. For the first time, conventional types of mutation (comprising coding sequence variants and variants at intron/exon boundaries) and gross genomic rearrangements were screened for in all four major pancreatitis genes, PRSS1, SPINK1, CTRC and CFTR. For the purposes of the study, synonymous, intronic and 5'- or 3'-untranslated region variants were excluded from the analysis except where there was persuasive evidence of functional consequences. The remaining sequence variants/genotypes were classified into causative, contributory or neutral categories by consideration of (i) their allele frequencies in patient and normal control populations, (ii) their presumed or experimentally confirmed functional effects, (iii) the relative importance of their associated genes in the pathogenesis of chronic pancreatitis and (iv) gene-gene interactions wherever applicable. Adoption of this strategy allowed us to assess the pathogenic relevance of specific variants/genotypes to their respective carriers to an unprecedented degree. The genetic cause of ICP could be assigned in 23.7% of individuals in the study group. A strong genetic susceptibility factor was also present in an additional 24.5% of cases. Taken together, up to 48.2% of the studied ICP patients were found to display evidence of a genetic basis for their pancreatitis. Whereas these particular proportions may not be extrapolable to all ICP patients, the approach employed should serve as a useful framework for acquiring a better understanding of the role of genetic factors in causing this oligogenic disease.

Hereditary pancreatitis: endoscopic and surgical management

INTRODUCTION

Hereditary pancreatitis is a rare cause of chronic pancreatitis. In recent years, genetic mutations have been characterized. The rarity of this disorder has resulted in a gap in clinical knowledge. The aims were to characterize patients with hereditary pancreatitis and establish clinical guidelines.

METHODS

Pediatric and adult endoscopic, surgical, radiologic, and genetic databases from 1998 to 2012 were searched. Patients with recurrent acute or chronic pancreatitis and genetic mutation for either PRSS-1, SPINK-1, or CFTR or those who met the family history criteria were included. Patients with pancreatitis due to other causes, without a positive family history, familial pancreatic cancer, or cystic fibrosis, were excluded.

RESULTS

Eighty-seven patients were identified. Genetic testing confirmed the diagnosis in 54 patients (62 %). Eighty-five patients (98 %) underwent 263 endoscopic procedures including sphincterotomy (72 %), stone removal (49 %), and pancreatic duct stenting (82 %). Twenty-eight patients (32 %) have undergone 37 operations which included 19 resections and 18 drainage procedures. The interval between procedures for recurrent pain was longer for surgery than for endoscopic therapy (9.1 vs. 3.4 years, p < 0.05).

CONCLUSIONS

Most children and young adults with hereditary pancreatitis can be managed initially with endoscopic therapy. When surgery is undertaken, the procedure should be tailored to the pancreatic anatomy and cancer risk.

Cerulein-induced chronic pancreatitis does not require intra-acinar activation of trypsinogen in mice

BACKGROUND & AIMS

Premature activation of trypsinogen activation can cause pancreatic injury and has been associated with chronic pancreatitis (CP). Mice that lack intra-acinar activation of trypsinogen, such as trypsinogen-7-null (T(-/-)) and cathepsin B-null (CB(-/-)) mice, have been used to study trypsin-independent processes of CP development. We compared histologic features and inflammatory responses of pancreatic tissues from these mice with those from wild-type mice after the development of CP.

METHODS

CP was induced in wild-type, T(-/-), and CB(-/-) mice by twice-weekly induction of acute pancreatitis for 10 weeks; acute pancreatitis was induced by hourly intraperitoneal injections of cerulein (50 μg/kg × 6). Pancreatic samples were collected and evaluated by histologic and immunohistochemical analyses. Normal human pancreas samples, obtained from the islet transplant program at the University of Minnesota, were used as controls and CP samples were obtained from surgical resections.

RESULTS

Compared with pancreatic tissues from wild-type mice, those from T(-/-) and CB(-/-) mice had similar levels of atrophy, histomorphologic features of CP, and chronic inflammation. All samples had comparable intra-acinar activation of nuclear factor (NF)-κB, a transcription factor that regulates the inflammatory response, immediately after injection of cerulein. Pancreatic tissue samples from patients with CP had increased activation of NF-κB (based on nuclear translocation of p65 in acinar cells) compared with controls.

CONCLUSIONS

Induction of CP in mice by cerulein injection does not require intra-acinar activation of trypsinogen. Pancreatic acinar cells of patients with CP have increased levels of NF-κB activation compared with controls; regulation of the inflammatory response by this transcription factor might be involved in the pathogenesis of CP.

Genetics and pathogenesis of chronic pancreatitis: the 2012 update

Chronic pancreatitis is a persistent inflammation of the pancreas that results in irreversible morphological changes and impairment of both exocrine and endocrine functions. Genetic studies of the disease over the past 15 years have led to the identification of four firmly established susceptibility genes namely PRSS1, SPNIK1, CTRC and CFTR. Our previously published review (Chen and Férec. Annu Rev Genomics Hum Genet 2009) has comprehensively summarized the advances made in terms of genetics and pathogenesis of chronic pancreatitis, covering the data available up to early 2009. This review summarizes the important and representative findings published thereafter, focusing on (i) newly found disease-causing mutations, (ii) functional characterization of known variations and (iii) genotype and phenotype relationship.

Genetic prevalence and characteristics in children with recurrent pancreatitis

AIMS

The causes of chronic (CP) and recurrent acute pancreatitis (RAP) in children include anatomic abnormalities and hereditary, metabolic, and autoimmune disorders, with a significant proportion of cases being labeled as idiopathic. Genetic pancreatitis (GP) is associated with mutations of cystic fibrosis transmembrane conductor regulator gene (CFTR), cationic trypsinogen (PRSS1) gene, and serine protease inhibitor Kazal type 1 (SPINK1). There literature is sparse regarding the clinical profile of GP in children. The aim of the present study was to estimate the prevalence and describe the clinical characteristics and outcome of genetic pancreatitis.

METHODS

We reviewed the charts of children ages 18 years or younger with RAP or CP diagnosed from 2000 to 2009 at the Children's Hospital of Wisconsin, Milwaukee. Twenty-nine patients with RAP or CP were identified, of whom 23 (79%) were positive for mutations in ≥1 of the above-mentioned genes, and were included for review.

RESULTS

The median age of symptom onset was 5 years (range 9 months-15 years) with diagnosis at 6.5 years (range 1-16 years). Twenty-one were white; 14 were girls. The most common presenting symptoms were abdominal pain and vomiting. Patients with RAP had 2 to 8 episodes of pancreatitis during 3.6-year average follow-up. Family history was positive in 5 of 29 of gene-tested patients. CFTR, SPINK1, or PRSS1 mutations were seen in 14 (48%), 8 (27%), and 7 (24%) patients, respectively. Two patients were homozygous for CFTR mutations, 6 heterozygote and 4 patients had 5 T variants. Two other patients had double heterozygous mutations in F508 del/2789 + 5G > A and F508 del/5T variant. Six patients with CP had a combination of CFTR and SPINK1 or PRSS1 mutations. Eleven of 29 (38%) patients met radiological criteria for CP. All of the heterozygote patients with a combination of CFTR and SPINK1 or PRSS1 mutations had CP. Eight patients developed a chronic pain syndrome and 2 developed exocrine pancreatic insufficiency during follow-up.

CONCLUSIONS

We found a high prevalence of genetic mutations in patients without anatomic or metabolic abnormalities known to be associated with pancreatitis. Studies are needed to ascertain the genetic causes of RAP and CP and examine the relation between single CFTR mutations and single mutations in the PRSS1 and SPINK1 genes.

Role of proteases and antiprotease in the etiology of chronic pancreatitis

BACKGROUND/AIM

Chronic pancreatitis (CP) is the progressive and irreversible destruction of the pancreas characterized by the permanent loss of endocrine and exocrine function. Trypsin, the most important digestive enzyme plays a central role in the regulation of all other digestive enzymes. Chymotrypsin, an endopeptidase hydrolyzes peptides at amino acids with aromatic side chains. Alpha-1-antitrypsin is a principal antiprotease which protects the mucosal tissue from the proteolytic effects of trypsin and chymotrypsin by the formation of molar complexes. The present study is aimed at examining the role of proteases (trypsin and chymotrypsin) and anti-protease (α1-anti-trypsin) in the etiopathogenesis of chronic pancreatitis.

PATIENTS AND METHODS

A total of 90 CP patients and 110 age and sex matched controls were considered for the study. Serum trypsin, chymotrypsin and α1-anti-trypsin levels were determined prospectively in CP patients and compared to healthy controls as described previously.

RESULTS

The mean activity of trypsin were found to be increased in CP patients (X ± SD = 0.82 ± 0.838) in comparison to normal control group (X ± SD = 0.55 ± 0.328), (P = 0.001). Chymotrypsin activity were also found to be elevated in CP patients (X ± SD = 0.63 ± 0.278) in comparison to control group (X ± SD = 0.39 ± 0.295), (P = 0.0001). The mean α-1-anti-trypsin activity were found to be lowered in CP patients (X ± SD = 0.42 ± 0.494) in comparison to control group (X ± SD = 0.67 ± 0.465), with the variation being significant (P = 0.0003).

CONCLUSION

The findings suggest an imbalance in the synthesis and degradation of proteolytic enzymes and antiprotease indicating an altered aggressive and defensive role in the pathogenesis of chronic pancreatitis.

Recommendations for the classification of diseases as CFTR-related disorders

Several diseases have been clinically or genetically related to cystic fibrosis (CF), but a consensus definition is lacking. Here, we present a proposal for consensus guidelines on cystic fibrosis transmembrane conductance regulator (CFTR)-related disorders (CFTR-RDs), reached after expert discussion and two dedicated workshops. A CFTR-RD may be defined as "a clinical entity associated with CFTR dysfunction that does not fulfil diagnostic criteria for CF". The utility of sweat testing, mutation analysis, nasal potential difference, and/or intestinal current measurement for the differential diagnosis of CF and CFTR-RD is discussed. Algorithms which use genetic and functional diagnostic tests to distinguish CF and CFTR-RDs are presented. According to present knowledge, congenital bilateral absence of vas deferens (CBAVD), acute recurrent or chronic pancreatitis and disseminated bronchiectasis, all with CFTR dysfunction, are CFTR-RDs.

[Pancreatitis in cystic fibrosis: association with genotype and pancreatic status]

INTRODUCTION

Pancreatitis is an uncommon complication of cystic fibrosis (CF). Either single or recurrent acute episodes can occur and it occasionally may follow a protracted course with relentless destruction of the pancreas. Moreover mild mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) have been found in many cases of idiopathic chronic pancreatitis. We describe a group of patients with CF who had one or more episodes of pancreatitis. We have estimated its prevalence in a large population of patients with CF across Spain.

METHODS

A retrospective descriptive study was conducted by collecting the demographic, clinical and laboratory data, pancreatic status and genotype of CF patients who attended the CF Units in 5 Spanish hospitals.

RESULTS

The overall number of CF patients under follow-up in the five centres was 520, of which 17 cases with pancreatitis were identified. The prevalence of pancreatitis in this population was 3.3%, higher than previously reported. Noticeably eight of the 17 patients (47.06%) had pancreatic insufficiency. This appears to be, partly, in contrast with that classically found, as this complication is usually associated with patients with a certain level of pancreatic reserve. No associations with genotype, age, gender or other factors were found.

CONCLUSIONS

The prevalence of pancreatitis in our CF patients was higher than that found in other CF populations, and was not limited to patients with pancreatic sufficiency. It occurred mostly in teenagers and young adults often with mild pulmonary disease. The CF genotype was variable. The course of the patients should be carefully monitored, and further information on the long-term outcome of larger cohorts of patients is needed.

A novel exon duplication of the cystic fibrosis transmembrane conductance regulator in a patient presenting with adult-onset recurrent pancreatitis

Pancreatitis is a rare occurrence in patients with cystic fibrosis (CF) affecting 1.2% of all patients, but it can be the first presenting sign in approximately 15% of adults with pancreatic sufficiency and a milder CF phenotype. We report a case of a woman with recurrent pancreatitis who has one cystic fibrosis-causing mutation (G551D) and the first known description of a pathologic duplication of exon 19 of the CF transmembrane conductance regulator (CFTR). A 30-year-old white woman with 30 attacks of pancreatitis over a 5-year period starting at age 25 presented to the genetics department. She was found to have a mutation in the SPINK1 gene, IVS3+184T>A, and one cystic fibrosis-causing mutation (G551D) prompting full gene sequencing of the CFTR, revealing an additional duplication of exon 19. Sweat chloride testing was elevated at 97 and 106 mmol/L. Despite normal growth parameters and lung function, it is important to be aware of recurrent pancreatitis as a presenting sign of CF. Comprehensive CF gene analysis is necessary to detect a second CF-causing mutation that may put patients at risk for more severe symptoms of pancreatitis. There is a significant difference in the prevalence of heterozygote mutations between available testing methods.

Molecular biology of pancreatic cancer

In spite of continuous research efforts directed at early detection and treatment of pancreatic cancer, the outlook for patients affected by the disease remains dismal. With most cases still being diagnosed at advanced stages, no improvement in survival prognosis is achieved with current diagnostic imaging approaches. In the absence of a dominant precancerous condition, several risk factors have been identified including family history, chronic pancreatitis, smoking, diabetes mellitus, as well as certain genetic disorders such as hereditary pancreatitis, cystic fibrosis, familial atypical multiple mole melanoma, and Peutz–Jeghers and Lynch syndromes. Most pancreatic carcinomas, however, remain sporadic. Current progress in experimental molecular techniques has enabled detailed understanding of the molecular processes of pancreatic cancer development. According to the latest information, malignant pancreatic transformation involves multiple oncogenes and tumor-suppressor genes that are involved in a variety of signaling pathways. The most characteristic aberrations (somatic point mutations and allelic losses) affect oncogenes and tumor-suppressor genes within RAS, AKT and Wnt signaling, and have a key role in transcription and proliferation, as well as systems that regulate the cell cycle (SMAD/DPC, CDKN2A/p16) and apoptosis (TP53). Understanding of the underlying molecular mechanisms should promote development of new methodology for early diagnosis and facilitate improvement in current approaches for pancreatic cancer treatment.

Pancreatitis, Other Inflammatory Lesions, and Pancreatic Pseudotumors

The pancreas is versatile in the diversity of disorders that it can exhibit. In this article, characteristics of disorders such as chronic, autoimmune, eosinophilic, hereditary, and infectious pancreatitis are described. With regard to autoimmune pancreatitis, the role of clinical evaluation, histologic examination, and IgG4 immunohistochemistry is discussed. The role of pancreatitis in the pathogenesis of diabetes is also mentioned. Some implications of pancreatitis are highlighted, including the neoplastic predisposition caused by inflammatory lesions of the pancreas. The goal of this article is to convey an appreciation of these disorders because their recognition can benefit patients tremendously, as inflammatory lesions of the pancreas can be mass-forming, giving rise to pseudotumors, and leading to surgical resection that may otherwise be unnecessary.

Assessing the pathological relevance of SPINK1 promoter variants

The SPINK1 gene, encoding the human pancreatic secretory trypsin inhibitor, is one of the major genes involved in predisposition to chronic pancreatitis (CP). In this study we have assessed the potential functional impact of 11 SPINK1 promoter variants by means of both luciferase reporter gene assay and electrophoretic mobility shift assay (EMSA), using human pancreatic COLO-357 cells as an expression system. The 11 promoter variants were found to be separable into three distinct categories on the basis of the reporter gene assay results viz loss-of-function, gain-of-function and functionally neutral. These findings, which were validated by EMSA, concurred with data from previous deletion studies and DNase I footprinting assays. Further, binding sites for two transcription factors, HNF1 and PTF1, were newly identified within the SPINK1 promoter by virtue of their being affected by specific variants. Combining the functional data with epidemiological data (derived by resequencing the SPINK1 promoter region in French, German and Indian CP patients and controls), then allowed us to make meaningful inferences as to each variant's likely contribution to CP. We conclude that only the three promoter variants associated with a loss-of-function (ie, −53C>T, −142T>C and −147A>G) are likely to be disease-predisposing alterations.

Intragenic duplication: a novel mutational mechanism in hereditary pancreatitis

OBJECTIVES

In a hereditary pancreatitis family from Denmark, we identified a novel intragenic duplication of 9 nucleotides in exon-2 of the human cationic trypsinogen (PRSS1) gene (c.63_71dup) which at the amino-acid level resulted in the insertion of 3 amino acids within the activation peptide of cationic trypsinogen (p.K23_I24insIDK). The aim of the present study was to characterize the effect of this unique genetic alteration on the function of human cationic trypsinogen.

METHODS

Wild-type and mutant cationic trypsinogens were produced recombinantly and purified to homogeneity. Trypsinogen activation was followed by enzymatic assays and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Trypsinogen secretion was measured from transfected HEK 293T cells.

RESULTS

Recombinant cationic trypsinogen carrying the p.K23_I24insIDK mutation exhibited greater than 10-fold increased autoactivation. Activation by human cathepsin B also was accelerated by 10-fold. Secretion of the p.K23_I24insIDK mutant from transfected cells was diminished, consistent with intracellular autoactivation.

CONCLUSIONS

This is the first report of an intragenic duplication within the PRSS1 gene causing hereditary pancreatitis. The accelerated activation of p.K23_I24insIDK by cathepsin B is a unique biochemical property not found in any other pancreatitis-associated trypsinogen mutant. In contrast, the robust autoactivation of the novel mutant confirms the notion that increased autoactivation is a disease-relevant mechanism in hereditary pancreatitis.

The etiology of acute recurrent pancreatitis in children: a challenge for pediatricians

OBJECTIVES

To assess specific etiologies of acute recurrent pancreatitis at a single Italian pediatric cystic fibrosis (CF) center.

METHODS

We studied, retrospectively, 78 young patients (39 female subjects; mean age at diagnosis, 8.8 ± 5.1 years) affected by acute recurrent episodes of pancreatitis, remained etiologically undiagnosed at first-level assessment. All patients were submitted to endoscopic retrograde cholangiopancreatography to exclude biliopancreatic malformations and tested for CF by a sweat chloride test. Most patients also were studied for the research of CFTR, PRSS1, and SPINK1 gene mutations.

RESULTS

A high percentage of family history for chronic pancreatitis was observed (20.5%). The sweat test identified 8 subjects (10.3%) with classic CF (2 patients) or at risk for CF (6 patients). Genetic analysis showed mutations in CFTR, SPINK1, and PRSS1 genes in 39.6%, 7.1%, and 4.5% of patients, respectively. A biliopancreatic malformation was diagnosed in 15 patients (19.2%). We also observed biliary lithiasis (5 patients [6.5%]), congenital pancreatic polycystosis (2 patients), a case of dyslipidemia, and 1 patient with a posttransplantation, drug-induced pancreatitis.

CONCLUSIONS

Recurrent pancreatitis in children has several etiologies. Genetic testing confirms the high frequency of CFTR mutations. This suggests that it is of some value to identify patients with late-onset CF and CFTR-related disorders.