Linkage studies in a large kindred with hereditary pancreatitis confirms mapping of the gene to a 16-cM region on 7q

Mutations of the cationic trypsinogen gene in patients with hereditary pancreatitis

BACKGROUND

Hereditary pancreatitis has been shown to be caused by one of two mutations (R117H and N21I) of the cationic trypsinogen gene (PRSS1). Families with hereditary pancreatitis in the north of England were investigated for these mutations. The clinical features associated with each mutation were compared.

METHODS

In individuals from nine families with hereditary pancreatitis, DNA was screened for the R117H and N21I mutations. All five exons of the cationic trypsinogen gene were also sequenced to search for additional mutations. Haplotype analysis was carried out to identify common ancestors. Clinical data were collected.

RESULTS

The R117H mutation was identified in three families and N21I in a further five. The R117H mutation was associated with a more severe phenotype than N21I in terms of mean(s.d.) age of onset of symptoms (8.4(7.2) versus 16. 5(7.1) years; P = 0.007) and requirement for surgical intervention (eight of 12 versus four of 17 patients respectively; P = 0.029). Haplotype analysis suggested that each mutation had arisen more than once.

CONCLUSION

Two mutations in the cationic trypsinogen gene cause hereditary pancreatitis in eight of nine families originating in this region. The R117H mutation is associated with a more severe form of the disease in terms of age at onset of symptoms and requirement for surgical intervention.

Molecular understanding of chronic pancreatitis: a perspective on the future

Despite the recent development of medical imaging technology, chronic pancreatitis can only be diagnosed when the disease is fully established. This is due to the lack of specific and sensitive markers for this disease. The discovery of mutations in the cationic trypsinogen gene in patients with hereditary pancreatitis and a high incidence of mutations in the cystic fibrosis transmembrane conductance regulator gene in patients with chronic pancreatitis might be important clues to understanding the molecular mechanisms of this disease. The interaction between ethanol and ion channels might be the missing link between alcohol ingestion and chronic pancreatitis.

The spectrum of complications of hereditary pancreatitis. Is this a model for future gene therapy?

Hereditary pancreatitis is an unusual form of acute and chronic pancreatitis that is usually associated with two specific mutations in the cationic trypsinogen gene. The extensive information available on the biochemistry, cell biology, and molecular biology of cationic trypsinogen and its gene provides the groundwork for development of a variety of therapeutic strategies, including gene therapy. Several features of this disease, however, make gene therapy unlikely in the near future. Further research using new models, including transgenic animals, is required before breakthroughs in therapy can be expected.

Implications of molecular diagnostic testing in families with hereditary pancreatitis

Hereditary Pancreatitis (HP), is an autosomal dominant trait, which presents with recurrent attacks of abdominal pain, and is the most common cause of chronic relapsing pancreatitis in children. In addition to recurring episodes of intense epigastric pain, patients have nausea, vomiting, and anorexia, and typically show elevated serum amylase levels during the acute episode that can rapidly decline in convalescence. Complications of long-standing disease include features of chronic pancreatitis, such as pancreatic pseudo-cyst, exocrine and endocrine failure, parenchymal calcification, and pancreatic cancer. A large family from Virginia, which was originally studied by Katwinkle and Lapey in 1973, was re-ascertained through a new proband. Linkage studies in this family mapped the gene to the 7q35 region, with similar results being reported simultaneously by two other groups. A pathogenic G to A transition mutation in exon 3 of the cationic trypsinogen (CT) gene, which had previously been mapped to this region, was found both in our family as well as other families from North America. Many other conditions can produce abdominal symptoms that are often mis-attributed to the disease in HP families. An affected member of our family in whom the mutation was confirmed by direct sequencing of exon 3 of the cationic trypsinogen gene requested diagnostic testing on his 4-year-old son because of onset of severe abdominal pain and vomiting. Screening for the mutation in this child did not reveal the pathogenic G to A change. These results prevented unnecessary invasive diagnostic procedures and treatment in this child. The pre-symptomatic testing of high risk individuals could, thus, have a significant impact on the well being of both affected and normal family members.

Hereditary pancreatitis. Gene defects and their implications

Hereditary pancreatitis is a rare condition characterized by acute and chronic pancreatitis transmitted in an autosomal dominant fashion. There also is an epidemiologic link to pancreatic cancer in some affected families. Failure of a secondary brake mechanism responsible for inactivation of prematurely activated cationic trypsin in acinar cells seems to be the fundamental defect in type I hereditary pancreatitis (R117H cationic trypsin), and also may explain the pathogenesis of type II hereditary pancreatitis (N211 cationic trypsin). The diagnosis is made based on clinical history and, in certain cases, by molecular diagnostic testing for these gene defects. Medical management of acute and chronic hereditary pancreatitis currently does not differ from that of nonhereditary AP. As in nonhereditary pancreatitis, the surgical approach must be tailored to the individual problem, with an understanding that disease restricted to the head of the gland is atypical and that residual acinar tissue continues to drive the disease state. Although diagnosis and management of pancreatic adenocarcinoma are similar in this cohort, the increased age-accumulated risk suggests that thoughtful screening protocols eventually may be clinically and cost-effective.

A signal peptide cleavage site mutation in the cationic trypsinogen gene is strongly associated with chronic pancreatitis

BACKGROUND & AIMS

In pancreatitis, a key role has been attributed to the inappropriate conversion of trypsinogen to trypsin. Recently, two mutations of the cationic trypsinogen gene were found in families with hereditary pancreatitis. This study was conducted to determine the spectrum and frequency of cationic trypsinogen mutations in unrelated patients with idiopathic or hereditary chronic pancreatitis (CP).

METHODS

DNA samples from 44 unrelated children and adolescents with CP (30 patients with idiopathic CP and 14 with hereditary CP) and from 56 family members were investigated. The cationic trypsinogen gene was screened for mutations by single-strand conformation polymorphism analysis and DNA sequencing.

RESULTS

A mutation in the cationic trypsinogen gene was detected in 5 patients: in 2 patients with a family history of CP and in 3 patients with idiopathic CP. In 1 patient the formerly described R122H mutation was detected. In 4 patients a hitherto unknown mutation was found at the signal peptide cleavage site leading to an alanine to valine exchange in codon 16. The mutations were inherited in all cases. In 95 unrelated control individuals the A16V mutation was not found.

CONCLUSIONS

Heterozygosity for the A16V mutation is strongly associated with CP. These results indicate that a significant percentage of patients with idiopathic CP may have a genetic basis for their disorder; therefore, genetic testing should be included in the diagnostic evaluation of these patients.

Hereditary pancreatitis and pancreatic carcinoma

Few risk factors for pancreatic cancer have emerged except for chronic pancreatitis. Recently, hereditary pancreatitis was estimated to carry a standardized incidence ratio of 53, a risk about 25 times higher than smoking. A review of the ongoing hereditary pancreatitis study of the Midwest Multicenter Pancreatic Study Group suggests that the risk of pancreatic cancer is related to long-standing pancreatitis rather than to the cationic trypsinogen mutations. No recommendations can be made on screening patients with hereditary pancreatitis for pancreatic cancer at this time. However, prospective data, serum, and pancreatic juice should be collected and banked on consenting patients at risk as part of prospective, multicenter trials so that evidence-based recommendations for hereditary pancreatitis and other types of chronic pancreatitis can be made in the future.

New insights into hereditary pancreatitis

The recent discovery that mutations in the trypsinogen gene are responsible for acute and chronic pancreatitis, and that patients with hereditary pancreatitis are at great risk for pancreatic cancer, has opened the door to understanding many aspects of pancreatic disease. This review focuses on the clinical presentation of hereditary pancreatitis, the mechanism of disease, and implications of this disease on understanding acute and chronic pancreatitis.

Mutations in exons 2 and 3 of the cationic trypsinogen gene in Japanese families with hereditary pancreatitis

BACKGROUND/AIMS

Single-point mutations in the cationic trypsinogen gene have been reported in hereditary pancreatitis kindreds in the white population. The aim of the present study was to investigate whether similar gene mutations are present in Japanese hereditary pancreatitis kindreds.

METHODS

All five exons of the cationic trypsinogen gene were amplified by polymerase chain reaction and sequenced in six Japanese families with hereditary pancreatitis.

RESULTS

Two types of single-point mutation in the cationic trypsinogen gene, which were identical with those reported in white families with hereditary pancreatitis, were observed in separate Japanese families with hereditary pancreatitis: 21Asn (AAC) to Ile (ATC) (N21I) in exon 2 and 117Arg (CGC) to His (CAC) (R117H) in exon 3. Pancreatitis occurred at more advanced ages in patients with the N21I mutation than in those with the R117H mutation. Besides normal polymorphisms in exons 4 and 5, no mutation was found in patients in the remaining four families with hereditary pancreatitis, 21 patients with sporadic chronic pancreatitis, or five normal subjects.

CONCLUSIONS

These results show heterogeneity, but no racial specificity, in the cationic trypsinogen gene mutations in hereditary pancreatitis kindreds. A distinctive clinical feature for each of the mutation types is suggested: adult onset for the N21I mutation and childhood onset for the R117H mutation.

Identification of a hereditary pancreatitis mutation in four West Virginia families

Hereditary pancreatitis (HP) is the second most common cause of chronic childhood pancreatitis in the United States. Mutations in the cationic trypsinogen gene on chromosome 7 are known to cause HP. We identified four families in West Virginia with symptoms consistent with HP. To determine whether members of these families had defects in the trypsinogen gene, we tested for linkage between the HP gene and simple tandem repeat markers on chromosome 7q and screened for a specific mutation in the cationic trypsinogen gene. Two-point linkage analysis indicated that the disease gene is closely linked to three 7q markers (D7S661, D7S2511, and D7S1805). Restriction fragment length polymorphism analysis showed that all clinically affected members and nonpenetrant carriers from the four families carried a G to A mutation in the third exon of the trypsinogen gene. These findings indicate that this mutation is the cause of HP in the families in our study. The observation that most individuals who carry the mutation have symptoms of HP is consistent with the high but incomplete penetrance of the trait. The presence of a single mutation and a common linked haplotype indicates that the defective allele arose in an ancestor common to all four families.

Alternative Splicing of Human NrCAM in Neural and Nonneural Tissues

Neural cell adhesion molecule NrCAM exists in a variety of isoforms as a result of alternative splicing of individual exons during RNA processing. In this report we demonstrate that many of the alternative splicing events described for chick are conserved in man and describe a novel variant of NrCAM cDNA. Furthermore, we show that NrCAM is expressed at significant levels outside the nervous system; in particular in pancreas, adrenal glands, and placenta and that expression in both brain and other tissues is accompanied by a very variable pattern of exon utilization in fetal and adult cells. Copyright 1998 Academic Press.