Clinical characterization of patients with hereditary pancreatitis and mutations in the cationic trypsinogen gene

Role of genetic disorders in acute recurrent pancreatitis

There was remarkable progress in the understanding of the role genetic risk factors in chronic pancreatitis. These factors seem to be much more important than thought in the past. The rare autosomal-dominant mutations N29I and R122H of PRSS1 (cationic trypsinogen) as well as the variant N34S of SPINK1 (pancreatic secretory trypsin inhibitor) are associated to a disease onset in childhood or youth. Compared to chronic alcoholic pancreatitis the progression is slow so that for a long time only signs of acute-recurrent pancreatitis are found. Only at later time points (more than 10-15 years) there is evidence for chronic pancreatitis in the majority of patients. Acute recurrent pancreatitis may therefore be regarded as a transition state until definite signs of chronic pancreatitis are detectable.

Hereditary chronic pancreatitis

Hereditary chronic pancreatitis (HCP) is a very rare form of early-onset chronic pancreatitis. Apart from young age at diagnosis and a slower progression, the clinical course, morphological features and laboratory findings of HCP do not differ from those of patients with alcoholic chronic pancreatitis. Diagnostic criteria and treatment of HCP also resemble those of chronic pancreatitis of other causes. The clinical presentation is highly variable and includes chronic abdominal pain, impairment of endocrine and exocrine pancreatic function, nausea and vomiting, maldigestion, diabetes, pseudocysts, bile-duct and duodenal obstruction, and rarely pancreatic cancer. Fortunately, the disease is mild in most patients. Mutations in the PRSS1 gene, encoding cationic trypsinogen, play a causative role in chronic pancreatitis. It has been shown that the PRSS1 mutations increase autocatalytic conversion of trypsinogen to active trypsin, and thus probably cause premature, intrapancreatic trypsinogen activation, disturbing the intrapancreatic balance of proteases and their inhibitors. Other genes--such as the anionic trypsinogen (PRSS2), the serine protease inhibitor Kazal type 1 (SPINK1), and the cystic fibrosis transmembrane conductance regulator (CFTR)--have also been found to be associated with chronic pancreatitis (idiopathic and hereditary). Genetic testing should only be performed in carefully selected patients by direct DNA sequencing, and antenatal diagnosis should not be encouraged. Treatment focuses on enzyme and nutritional supplementation, pain management, pancreatic diabetes, and local organ complications such as pseudocysts and bile-duct or duodenal obstruction. The disease course and prognosis of patients with HCP is unpredictable. The risk of pancreatic cancer is elevated. Therefore, HCP patients should strongly avoid environmental risk factors for pancreatic cancer.

The M-ANNHEIM classification of chronic pancreatitis: introduction of a unifying classification system based on a review of previous classifications of the disease

BACKGROUND

Several classification systems of chronic pancreatitis have been proposed to provide a basis for treatment and research. All of these previous classifications were designed at the height of pancreatic research of their respective times; thus, each represented the most current knowledge available to pancreatologists at the time. However, none of these classifications provide simultaneously a simple standardized system for the clinical classification of chronic pancreatitis according to etiology, clinical stage, and severity of the disease, nor are they consistently useful for directing clinical practice and comparing interinstitutional data. Thus, we aimed to develop a new classification system of chronic pancreatitis to provide a framework for studying the interaction of various risk factors on the course of the disease.

METHODS

We reviewed the literature on the clinical course of all different forms of chronic pancreatitis, and we reviewed all previous classification systems of the disease. This approach provided a basis for the development of a new and unifying classification of chronic pancreatitis.

RESULTS

We established the M-ANNHEIM multiple risk factor classification system based on the current knowledge of acute and chronic pancreatitis. This classification allows patients to be categorized according to the etiology, clinical stage, and severity of their disease. The severity of pancreatic inflammation was assessed using a scoring system that takes into account the clinical symptoms and treatment options of chronic pancreatitis. Finally, four hypothetical patients were categorized according to the M-ANNHEIM classification system to provide examples of its applicability in clinical practice.

CONCLUSIONS

The M-ANNHEIM multiple risk factor classification system is simple, objective, accurate, and relatively noninvasive, and it incorporates etiology, different stages of the disease, and various degrees of clinical severity. This new classification system will be helpful for investigating the impact and interaction of various risk factors on the course of the disease and will facilitate the comparison and combination of interinstitutional data.

Hereditary chronic pancreatitis

Hereditary chronic pancreatitis (HCP) is a very rare form of early onset chronic pancreatitis. With the exception of the young age at diagnosis and a slower progression, the clinical course, morphological features and laboratory findings of HCP do not differ from those of patients with alcoholic chronic pancreatitis. As well, diagnostic criteria and treatment of HCP resemble that of chronic pancreatitis of other causes. The clinical presentation is highly variable and includes chronic abdominal pain, impairment of endocrine and exocrine pancreatic function, nausea and vomiting, maldigestion, diabetes, pseudocysts, bile duct and duodenal obstruction, and rarely pancreatic cancer. Fortunately, most patients have a mild disease. Mutations in the PRSS1 gene, encoding cationic trypsinogen, play a causative role in chronic pancreatitis. It has been shown that the PRSS1 mutations increase autocatalytic conversion of trypsinogen to active trypsin, and thus probably cause premature, intrapancreatic trypsinogen activation disturbing the intrapancreatic balance of proteases and their inhibitors. Other genes, such as the anionic trypsinogen (PRSS2), the serine protease inhibitor, Kazal type 1 (SPINK1) and the cystic fibrosis transmembrane conductance regulator (CFTR) have been found to be associated with chronic pancreatitis (idiopathic and hereditary) as well. Genetic testing should only be performed in carefully selected patients by direct DNA sequencing and antenatal diagnosis should not be encouraged. Treatment focuses on enzyme and nutritional supplementation, pain management, pancreatic diabetes, and local organ complications, such as pseudocysts, bile duct or duodenal obstruction. The disease course and prognosis of patients with HCP is unpredictable. Pancreatic cancer risk is elevated. Therefore, HCP patients should strongly avoid environmental risk factors for pancreatic cancer.

Characterisation of a transgenic mouse expressing R122H human cationic trypsinogen

BACKGROUND

The R122H mutation of the cationic trypsinogen was found in patients with hereditary pancreatitis. A transgenic animal carrying this mutation could be useful as a genetic model system of pancreatitis.

METHODS

Mice transgenic for the human R122H cationic trypsinogen were generated using the -205 fragment of the rat elastase promoter. The presence of the transgene was assayed in the DNA, in pancreatic mRNA and in zymogen granule lysates. Serum levels of amylase, lipase and cytokines (MCP-1, IL-6) were monitored and the histological appearance of the tissue was investigated. Pancreatitis was induced by 7 hourly injections of 50 mug/kg cerulein. The procedure was repeated twice weekly for 10 consecutive weeks. The animals were sacrificed 24 (n = 8) and 48 hours (n = 8) after the first injection and at the end of the whole treatment (n = 7).

RESULTS

The transgene was detected at the genomic level and in pancreatic mRNA. The corresponding protein was found in low amounts in zymogen granule lysates. R122H mice showed elevated pancreatic lipase, but there was no spontaneous development of pancreatitis within 18 months. After induction of pancreatitis, levels of lipase (after 24 hours) and amylase (after 48 hours) were higher in R122H mice compared to controls. Repeated treatment with cerulein resulted in a slightly more severe pancreatitis in R122H animals. Amylase, lipase, and the cytokine levels were similar to controls.

CONCLUSION

The R122H transgenic mouse failed to develop a spontaneous pancreatitis but a repeatedly provoked cerulein-induced pancreatitis led to a slightly more severe pancreatitis. The rather small difference in comparison to controls could be due to the low expression of the transgene in the mouse pancreas.

Genetic issues in pediatric pancreatitis

The number of hospitalizations in children with acute and chronic pancreatitis is increasing and accounts for significant morbidity. Acute pancreatitis is a reversible event involving diffuse inflammation of the pancreas with variable involvement of other regional tissues, remote organs, or both, whereas chronic pancreatitis is a process that produces irreversible changes in the pancreatic structure and function. Mutations in the gene encoding cationic trypsinogen have recently been identified to be associated with hereditary pancreatitis. Genetic mutations in the pancreatic secretory trypsin inhibitor and the cystic fibrosis transmembrane conductance regulator have been described to play a role in the development of pancreatitis as well. Mutations in the cytokine target genes relating to regulation of inflammation are likely to be important in determining the severity of pancreatitis. These findings, along with the advances in cell biology, have contributed to a better understanding of the pathophysiology of pancreatic diseases.

Mutations of human cationic trypsinogen (PRSS1) and chronic pancreatitis

Ten years ago, the groundwork for the discovery of the genetic basis of chronic pancreatitis was laid by linkage analyses of large kindreds with autosomal dominant hereditary chronic pancreatitis. Subsequent candidate gene sequencing of the 7q35 chromosome region revealed a strong association of the c.365G > A (p.R122 H) mutation of the PRSS1 gene encoding cationic trypsinogen with hereditary pancreatitis. In the following years, further mutations of this gene were discovered in patients with hereditary or idiopathic chronic pancreatitis. In vitro the mutations increase autocatalytic conversion of trypsinogen to active trypsin and thus probably cause premature, intrapancreatic trypsinogen activation in vivo. The clinical presentation is highly variable, but most affected mutation carriers have relatively mild disease. In this review, we summarize the current knowledge on trypsinogen mutations and their role in pancreatic diseases.

Germline mutations and gene polymorphism associated with human pancreatitis

A wide range of mutations and polymorphisms in genes that relate to pancreatic function seem to be involved in the development of pancreatitis. Some of these genetic alterations lead to disease phenotypes with unequivocal mendelian inheritance patterns, whereas others seem to act as modifier genes in conjunction with environ-mental or, as yet unidentified, genetic cofactors. This article reviews germline changes in the genes for trypsin, pancreatic secretory trypsin inhibitor, the cystic fibrosis conductance regulator, lipid metabolism proteins, inflammatory mediators for cytokines, and cathepsin B.

Trypsinogen mutations in pancreatic disorders

There are multiple PRSS1 mutations described in hereditary pancreatitis but only a minority of these are clinically relevant. The two most frequent point mutations are in exon 2 (N29I) and exon3 (R122H), found in diverse racial populations. Both mutations result in early onset pancreatitis but the mechanism underlying this phenotype is unclear. The frequency of these mutations in such diverse populations suggests they have spontaneously occurred many times. The origin of the major mutations may be explained by gene conversions, accounting for multiple founders. The implications are discussed in terms of mechanism of action of the mutations and clinical presentation.

Total Pancreatectomy for the Treatment of Chronic Pancreatitis: Indications, Outcomes, and Recommendations

Total pancreatectomy (TP) for chronic pancreatitis (CP) has not gained widespread acceptance because of concerns regarding technical complexity, diabetic complications, and uncertainty with respect to long-term pain relief. Records of patients having TP from 1997 to 2005 were reviewed. Patient presentation, etiology of disease, and the indication for TP were examined. Operative results were analyzed. Long-term results were critically assessed, including narcotic usage and the need for re-admission. Postoperative quality of life (QOL) was assessed by the SF-36 health survey. During the study period, 7 patients with CP had TP, and 28 had other operations. The etiology of CP was alcohol in four and hereditary pancreatitis in three. The indication for surgery was pain and weight loss. Preoperatively, all patients used narcotics chronically and two had insulin-dependent diabetes. Four had TP after failed previous surgical procedures. Endoscopic retrograde cholangiopancreatography and computed tomography demonstrated small ducts and atrophic calcified glands. The mean length of the operation was 468 minutes, and only two patients required transfusion. There were no biliary anastomotic complications. The mean length of stay was 14 days. Major morbidity was limited to a single patient with a leak from the gastrojejunal anastomosis. Thirty-day mortality was zero, with one late death unrelated to the surgical procedure or diabetes. The mean length of follow-up was 46 months. All patients remained alcohol and narcotic free. No patient was readmitted with a diabetic complication. When compared with the general population, QOL scores were diminished but reasonable. We conclude that TP is indicated in hereditary pancreatitis and in those with an atrophic, calcified pancreas with small duct disease; that TP is technically arduous but can be completed with very low morbidity and mortality; and that on long-term follow-up, pain relief and abstinence from alcohol and narcotics was excellent with an acceptable QOL.

Childhood pancreatitis

Inflammation of the pancreas has many presentations in children and adolescents. The etiology is often elusive, with a great number of cases being idiopathic. However, there have been a number of recent advances in the areas of cell biology, genetics and imaging technology, which should be highlighted. Herein is provided a review for the reader with particular emphasis on some of these newer advances.

Extracellular cleavage of E-cadherin by leukocyte elastase during acute experimental pancreatitis in rats

BACKGROUND & AIMS

Cadherins play an important role in cell-cell contact formation at adherens junctions. During the course of acute pancreatitis, adherens junctions are known to dissociate-a requirement for the interstitial accumulation of fluid and inflammatory cells-but the underlying mechanism is unknown.

METHODS

Acute pancreatitis was induced in rats by supramaximal cerulein infusion. The pancreas and lungs were either homogenized for protein analysis or fixed for morphology. Protein sequencing was used to identify proteolytic cleavage sites and freshly prepared acini for ex vivo studies with recombinant proteases. Results were confirmed in vivo by treating experimental pancreatitis animals with specific protease inhibitors.

RESULTS

A 15-kilodalton smaller variant of E-cadherin was detected in the pancreas within 60 minutes of pancreatitis, was found to be the product of E-cadherin cleavage at amino acid 394 in the extracellular domain that controls cell-contact formation, and was consistent with E-cadherin cleavage by leukocyte elastase. Employing cell culture and ex vivo acini leukocyte elastase was confirmed to cleave E-cadherin at the identified position, followed by dissociation of cell contacts and the internalization of cleaved E-cadherin to the cytosol. Inhibition of leukocyte elastase in vivo prevented E-cadherin cleavage during pancreatitis and reduced leukocyte transmigration into the pancreas.

CONCLUSIONS

These data provide evidence that polymorphonuclear leukocyte elastase is involved in, and required for, the dissociation of cell-cell contacts at adherens junctions, the extracellular cleavage of E-cadherin, and, ultimately, the transmigration of leukocytes into the epithelial tissue during the initial phase of experimental pancreatitis.

Expression of mutated cationic trypsinogen reduces cellular viability in AR4-2J cells

Mutations in the human cationic trypsinogen are associated with hereditary pancreatitis. The cDNA coding for human cationic trypsinogen was subcloned into the expression vector pcDNA3. The mutations R122H, N29I, A16V, D22G, and K23R were introduced by site directed mutagenesis. We constructed an expression vector coding for active trypsin by subcloning the cDNA of trypsin lacking the coding region for the trypsin activating peptide behind an appropriate signal peptide. Expression of protein was verified by Western blot and measurement of enzymatic activity. AR4-2J cells were transiently transfected with the different expression vectors and cell viability and intracellular caspase-3 activity were quantified. In contrast to wild-type trypsinogen, expression of active trypsin and mutated trypsinogens reduced cell viability of AR4-2J cells. Expression of trypsin and R122H trypsinogen induced caspase-3 activity. Acinar cells might react to intracellular trypsin activity by triggering apoptosis.

Cationic Trypsinogen Mutations and Pancreatitis

The discovery of PRSS 1 mutations in hereditary pancreatitis and analysis of how the genotype affects the presentation and progression of hereditary pancreatitis has led to a better understanding of the pathophysiology of the disease. Patients with hereditary pancreatitis present with symptoms at an early age and have a significant lifetime risk for the development of endocrine and exocrine insufficiency, albeit at a later stage than patients with either idiopathic or alcoholic chronic pancreatitis. There are distinct phenotypic differences between hereditary pancreatitis and with other types of pancreatitis. As many as 80% of patients with symptomatic hereditary pancreatitis have an underlying causative PRSS1 mutation; there are, however, few significant phenotypic differences between these PRSS1 mutations. TheR122H mutation is the most common PRSS1 mutation observed, and patients with the R122H mutation present earlier. This, however, does not necessarily translate into a more aggressive disease with respect to complications of chronic pancreatitis. Indeed, the age of presentation of symptoms may be a poor surrogate for predicting outcome, as inherited disorders of trypsinogen may cause subclinical attacks of pancreatitis, which ultimately lead to pancreatic destruction and dysfunction. All patients, irrespective of whether they carry a PRSS1 mutation, are at significant risk of developing pancreatic ductal adenocarcinoma. The risk appears to be insignificant below the age of 40 years, but it increases incrementally thereafter. Significantly, the risk of pancreatic cancer is not related to PRSS1 mutation type and does not appear to be related to the mode of inheritance. The role of SPINK1 mutations in modifying the expression of PRSS1mutations is unclear but appears to be of clinical importance. It is unlikely that they act as causative mutations per se, at least in the Western form of the disease. Additionally, they do not appear to have an impact on the penetrance of PRSS1 gene mutations in hereditary pancreatitis.

[Clinical implications of genetic risk factors of chronic pancreatitis]

The identification of a specific mutation in the human cationic trypsinogen gene in large kindreds with hereditary pancreatitis was the key to understand the genetic background of chronic pancreatitis. Rapidly, other variants within the same gene were identified-even in small families with a minority of patients. Later, mutations of the most important intrapancreatic trypsin inhibitor SPINK1 were found with high prevalence in patients with idiopathic, tropical and alcoholic chronic pancreatitis. We summarize interesting genetic and biochemical findings, point to clinical features and review recommendations for genetic analysis, follow-up and cancer prevention.

Genetic counseling for hereditary pancreatitis--the role of molecular genetics testing for the cationic trypsinogen gene, cystic fibrosis and serine protease inhibitor Kazal type 1

The importance of pretest information, using an accredited DNA laboratory and interpreting the genotype on behalf of the patient and their physicians is emphasized. Care with predictive testing and the strong encouragement to involve a specialist genetic counseling service is made. A similar approach to genetic testing should be used when children are involved. Because of the incomplete pickup of PRSS1 mutations, particularly of a limited mutation panel of R122H and N291 (perhaps with A16V), a diagnosis of HP cannot be ruled out by molecular genetic testing alone. The A16V mutation has a reduced penetrance, and its contribution to pancreatitis remains unclear. The advice to patients with genetic forms of pancreatitis is a strong encouragement to avoid smoking, to avoid alcohol, and to remain in contact with clinical and research groups for their follow-up and screening trials for early pancreatic cancer. The remaining issues are of how wide to cast the net of investigation in patients with unexplained pancreatitis, particularly looking for mutations in the CFTR and lower penetrance genes such as PSTI/SPINK1.

Cationic trypsinogen mutations and pancreatitis

The discovery of PRSS1 mutations in hereditary pancreatitis and analysis of how the genotype affects the presentation and progression of hereditary pancreatitis has led to a better understanding of the pathophysiology of the disease. Patients with hereditary pancreatitis present with symptoms at an early age and have a significant lifetime risk for the development of endocrine and exocrine insufficiency, albeit at a later stage than patients with either idiopathic or alcoholic chronic pancreatitis. There are distinct phenotypic differences between hereditary pancreatitis and with other types of pancreatitis. As many as 80% of patients with symptomatic hereditary pancreatitis have an underlying causative PRSS1 mutation; there are, however, few significant phenotypic differences between these PRSS1 mutations. The R122H mutation is the most common PRSS1 mutation observed, and patients with the R122H mutation present earlier. This, however, does not necessarily translate into a more aggressive disease with respect to complications of chronic pancreatitis. Indeed, the age of presentation of symptoms may be a poor surrogate for predicting outcome, as inherited disorders of trypsinogen may cause subclinical attacks of pancreatitis, which ultimately lead to pancreatic destruction and dysfunction. All patients, irrespective of whether they carry a PRSS1 mutation, are at significant risk of developing pancreatic ductal adenocarcinoma. The risk appears to be insignificant below the age of 40 years, but it increases incrementally thereafter. Significantly, the risk of pancreatic cancer is not related to PRSS1 mutation type and does not appear to be related to the mode of inheritance. The role of SPINK1 mutations in modifying the expression of PRSS1 mutations is unclear but appears to be of clinical importance. It is unlikely that they act as causative mutations per se, at least in the Western form of the disease. Additionally, they do not appear to have an impact on the penetrance of PRSS1 gene mutations in hereditary pancreatitis.

Hereditary pancreatitis in a family of Aboriginal descent

Hereditary pancreatitis is an autosomal dominant condition characterized by recurrent episodes of acute pancreatitis, usually starting in childhood. We present a family who was ascertained when an 11-year-old girl presented with an episode of acute pancreatitis. Her father and other family members had also had recurrent bouts of acute pancreatitis. Genetic testing revealed a pathogenic mutation in the cationic trypsinogen gene in the proband, her father and her paternal grandmother. As far as we are aware, this is the first Aboriginal kindred with mutation-proven hereditary pancreatitis. Hereditary pancreatitis is an important differential diagnosis to consider in a patient with recurrent episodes of acute pancreatitis with no obvious precipitating cause. This family is of Aboriginal descent and the implications of the family's background are also discussed when considering the aetiology of the condition. We emphasize the need to ascertain a full family history from patients with a history of repeated episodes of acute pancreatitis and also emphasize the need to avoid ethnic stereotypes when assessing patients.

Interaction between trypsinogen isoforms in genetically determined pancreatitis: mutation E79K in cationic trypsin (PRSS1) causes increased transactivation of anionic trypsinogen (PRSS2)

The human pancreas secretes two major trypsinogen isoforms, cationic and anionic trypsinogen. To date, 19 genetic variants have been identified in the cationic trypsinogen gene (PRSS1) of patients with hereditary, familial, or sporadic chronic pancreatitis. A common feature of cationic trypsinogen mutants studied so far is an increased propensity for autocatalytic activation (autoactivation). This is thought to lead to premature intrapancreatic digestive protease activation. In contrast, no pancreatitis-associated mutations have been found in the anionic trypsinogen gene (PRSS2), suggesting that this isoform might play a relatively unimportant role in pancreatitis. To challenge this notion, here we describe the unique properties of the E79K cationic trypsinogen mutation (c.235G>A), which was identified in three European families affected by sporadic or familial pancreatitis cases. In vitro analysis of recombinant wild-type and mutant enzymes revealed that catalytic activity of E79K trypsin was normal, and its inhibition by pancreatic secretory trypsin inhibitor was unaffected. Although the E79K mutation introduces a potential new tryptic cleavage site, autocatalytic degradation (autolysis) of E79K-trypsin was also unchanged. Furthermore, in contrast to previously characterized disease-causing mutations, E79K markedly inhibited autoactivation of cationic trypsinogen. Remarkably, however, E79K trypsin activated anionic trypsinogen two-fold better than wild-type cationic trypsin did, while the common pancreatitis-associated mutants R122H or N29I had no such effect. The observations not only suggest a novel mechanism of action for pancreatitis-associated trypsinogen mutations, but also highlight the importance of interactions between the two major trypsinogen isoforms in the development of genetically determined chronic pancreatitis.

Clinical and genetic characteristics of hereditary pancreatitis in Europe

BACKGROUND & AIMS

Hereditary pancreatitis is an autosomal dominant disease that is mostly caused by cationic trypsinogen (PRSS1) gene mutations. The aim was to determine phenotype-genotype correlations of families in Europe.

METHODS

Analysis of data obtained by the European Registry of Hereditary Pancreatitis and Pancreatic Cancer was undertaken using multilevel proportional hazards modelling.

RESULTS

There were 112 families in 14 countries (418 affected individuals): 58 (52%) families carried the R122H, 24 (21%) the N29I, and 5 (4%) the A16V mutation, 2 had rare mutations, and 21 (19%) had no PRSS1 mutation. The median (95% confidence interval [CI]) time to first symptoms for R122H was 10 (8, 12) years of age, 14 (11, 18) years for N29I, and 14.5 (10, 21) years for mutation negative patients (P = 0.032). The cumulative risk (95% CI) at 50 years of age for exocrine failure was 37.2% (28.5%, 45.8%), 47.6% (37.1%, 58.1%) for endocrine failure, and 17.5% (12.2%, 22.7%) for pancreatic resection for pain. Time to resection was significantly reduced for females (P < 0.001) and those with the N29I mutation (P = 0.014). The cumulative risk (95% CI) of pancreatic cancer was 44.0% (8.0%, 80.0%) at 70 years from symptom onset with a standardized incidence ratio of 67% (50%, 82%).

CONCLUSIONS

Symptoms in hereditary pancreatitis start in younger patients and endpoints take longer to be reached compared with other forms of chronic pancreatitis but the cumulative levels of exocrine and endocrine failure are much higher. There is an increasingly high risk of pancreatic cancer after the age of 50 years unrelated to the genotype.

Hereditary pancreatitis: clinical characteristics and diagnostic criteria in Japan

BACKGROUND/AIM

Hereditary pancreatitis (HP) is the strongest known risk factor for pancreatic cancer. The aim of the present study is to establish diagnostic criteria for HP to predict and identify high-risk groups for pancreatic cancer.

METHOD

We collected clinical data for 210 patients with recurrent acute or chronic pancreatitis, and examined mutations of the cationic trypsinogen (CT) gene in 57 patients with a family history of pancreatitis or with early-onset idiopathic recurrent acute or chronic pancreatitis (40 years of age or younger). DNA was extracted from peripheral blood leukocytes, and exons 2 and 3 of the CT gene were individually amplified by polymerase chain reaction (PCR) and sequenced.

RESULTS

Of these 57 patients in whom mutations of the CT gene were examined, the R122H (20 patients) and N29I (5 patients) mutations in the CT gene were observed in 25 patients (43.9%). From the analysis of clinical records and the CT gene of these patients, we proposed the following adaptations to the diagnostic criteria for HP: (1) at least one of the affected members in a family has no known etiological factors, (2) we deleted the definition of "different generation", but included the upper limit of the age of onset of pancreatitis in the case of siblings (at least 1 of the patients in a family <40 years of age). According to these criteria, all patients with the CT gene mutations in the present study could be classified as having HP, with the exception of 2 sporadic cases with the R122H and N29I mutations, respectively. Based on these findings, we revised the criteria for the diagnosis of HP; (1) recurrent acute or chronic pancreatitis with R122H or N29I mutation of the CT gene, or (2) recurrent acute or chronic pancreatitis with a family history of 2 or more affected patients, irrespective of generation, with at least 1 of the patients having no known etiological factors, and in case of siblings only, the onset of the disease in at least 1 of the patients is under age 40 years.

CONCLUSION

The revised criteria in the present study are appropriate and of clinical usefulness to diagnose patients with HP even in cases without the genetic testing. However, if and when more genes are detected, it will be important to reexamine the mutation-negative patients now classified as HP based on our proposed criteria.

Genetic testing in chronic pancreatitis

Genetic changes associated with some forms of chronic pancreatitis have been recently defined. There are three genes that play a role, each with a variety of genotypes and different pathologic mechanisms and clinical correlations. Selection of the appropriate diagnostic tests requires integration of the clinical and family history and the interpretation of results has a significant impact on genetic counseling for the patient and family. The relative significance of some variant alleles is still under investigation as they are common in the population and show low penetrance. Knowledge of the pathophysiology of each abnormal allele could lead the way towards more specific therapeutic options in the future.

Analysis of tumour necrosis factor alpha and interleukin 10 promotor variants in patients with chronic pancreatitis

OBJECTIVE

Cationic trypsinogen gene mutations are strong risk factors of hereditary pancreatitis. However, 20% of subjects with a trypsinogen mutation never get pancreatitis and the cause of this incomplete penetrance is unknown. We investigated the influence of interleukin 10 (IL10) and tumour necrosis factor alpha (TNFalpha) promotor variants on the manifestation of chronic pancreatitis of different underlying causes and in pancreatic cancer.

METHODS

A total of 335 German patients with chronic pancreatitis were investigated. In 157 patients the disease was related to alcohol abuse; the other cases were of non-alcoholic origin. In the latter group, the serine protease inhibitor, Kazal type 1 (SPINK1) mutation N34S was found in 72 patients and the trypsinogen mutations N29I or R122H were present in 60 patients; in the remaining 46 patients no mutation was found. In addition, we studied 208 patients with pancreatic cancer. As controls, 116 healthy blood donors and 25 healthy carriers of the trypsinogen mutations N29I or R122H were investigated. After DNA extraction from blood leucocytes, genotyping for the cytokine polymorphisms was performed by induced heteroduplex generators and/or direct DNA sequencing of the IL10 and TNFalpha promotor regions.

RESULTS

The frequencies of the promotor polymorphisms of IL10-627A, IL10-1117A, TNF-238A and TNF-308A in patients with alcoholic chronic pancreatitis, idiopathic pancreatitis, SPINK1-N34S-associated chronic pancreatitis and pancreatic cancer did not differ significantly from the control group. The variant TNF-238A was two to four times more frequent in index patients with trypsinogen mutations than in all other groups. The analysis of the allelic frequencies of whole families with trypsinogen mutations revealed that all subjects with the TNF-238A variant suffered from chronic pancreatitis, whereas all intrafamilial controls with wild-type TNF were unaffected.

CONCLUSIONS

TNFalpha and IL10 promotor variants are not associated with a manifestation of chronic pancreatitis or pancreatic cancer. The variant TNF-238A, however, might be a relevant risk factor for disease manifestation in families with hereditary pancreatitis.

Identification of patients with genetic risk factors of pancreatitis: impact on treatment and cancer prevention

Recent data suggest that genetic alterations are relevant risk factors for chronic pancreatitis. The highest risk is associated with autosomal-dominant mutations (N29I, R122H) of the cationic trypsinogen (PRSS1). Further mutations were identified in the genes of the pancreatic trypsin inhibitor (SPINK1) and in the cystic fibrosis transmembrane conductance regulator (CFTR). A remarkable finding was that both molecules were also mutated in patients suffering from alcoholic chronic pancreatitis. According to recent estimations, genetic alterations may be regarded as more severe risk factors than chronic alcohol consumption. To identify patients with mutations, a positive family history could be of help, but mutations were also found in a significant number of those with a negative family history. On the other hand, in approximately 40% of the patients with a positive family history no mutations were found up to now. The age at onset is lower in patients with genetic risk factors; however, no clear limit can be denominated above which a screening is not appropriate. Therefore, in our department genetic screening is offered to all patients with chronic pancreatitis of unclear origin. There is no specific treatment in patients with a genetically based disease. The patients with familial pancreatitis-increased rates of pancreas cancer were described but there is no agreement concerning the prophylactic strategy. Prevention of cancer by routine pancreatectomy, though performed recently, is not justified at the moment. Clinical criteria may be more appropriate to decide the timing and the extent of the operation.

Genetics and pancreatic disease

The recognition that variations in the DNA sequence of key genes predispose individuals to acute pancreatitis, chronic pancreatitis, and pancreatic cancer represents one of the greatest breakthroughs in pancreas research. This review highlights recent progress in understanding mutations in the cationic trypsinogen gene, the pancreatic secretory trypsin inhibitor gene, and the cystic fibrosis transmembrane conductance regulator gene with respect to pancreatitis. It also notes progress in the use of microarray technology, classification of chronic pancreatitis, and predisposition to pancreatic cancer.