Evidence for a common mutation in hereditary pancreatitis

Association of SPINK1 gene mutation and CFTR gene polymorphisms in patients with pancreas divisum presenting with idiopathic pancreatitis

BACKGROUND

Pancreas divisum has been associated with idiopathic pancreatitis. However, the causal association remains controversial.

OBJECTIVE

To study the gene mutations in patients with pancreas divisum presenting with idiopathic pancreatitis.

METHODS

All consecutive patients with pancreas divisum presenting with recurrent pancreatitis were included in the study. Fifty healthy volunteers, 30 patients with chronic pancreatitis, and 14 patients with idiopathic recurrent acute pancreatitis without pancreas divisum served as controls. Patients and controls were tested for cationic trypsiongen gene, CFTR gene and SPINK1 gene mutations.

RESULTS

Of the 12 patients with pancreas divisum and idiopathic pancreatitis, 4 had SPINK1 N34S gene mutation-3 were heterozygous and 1 was homozygous, and 1 had P55S mutation compared with 1 of 50 healthy controls with N34S mutation (P=0.001). The frequency of SPINK1 mutation was similar among patients with pancreas divisum and pancreatitis (41.6%), chronic pancreatitis (43.3%), and recurrent acute pancreatitis without pancreas divisum (35.7%). Five patients with pancreas divisum had polymorphisms in the CFTR gene.

CONCLUSION

Patients with pancreas divisum presenting with idiopathic pancreatitis had a higher frequency of SPINK1 gene mutation compared with healthy controls, which might be responsible as the sole-factor or a co-factor in causing pancreatitis in them.

Pancreatitis in fibrocalculous pancreatic diabetes mellitus is not associated with common mutations in the trypsinogen gene

BACKGROUND

A distinct type of pancreatitis associated with diabetes, termed fibrocalculous pancreatic diabetes (FCPD), has been reported in tropical developing countries including Bangladesh. The molecular basis for autosomal dominant hereditary pancreatitis (HP) has recently been attributed to mutations in exons 2 and 3 of the trypsinogen gene. We have investigated the hypothesis that mutations in the aforementioned exons of this gene might also predispose to FCPD.

METHODS

Seventy Bangladeshi and 50 South Indian unrelated FCPD patients and seven South Indian families with FCPD probands were studied. Pancreatic calcification was confirmed by abdominal X-ray, ultrasound and/or ERCP. Established mutations of exons 2 and 3 of the trypsinogen gene were studied in these subjects by PCR-RFLP analysis and DNA sequencing.

RESULTS

The mutations found in hereditary pancreatitis were not observed in this collection of FCPD subjects, and complete DNA sequencing of exons 2 and 3 of the fourth cationic trypsinogen gene also excluded any new mutations.

CONCLUSIONS

These results indicate that chronic pancreatitis of FCPD is unlikely to be caused by common mutations in the trypsinogen gene.

Genes, cloned cDNAs, and proteins of human trypsinogens and pancreatitis-associated cationic trypsinogen mutations

Historically, trypsinogens/trypsins have been one of the most extensively studied enzyme models of protein structure and function. They have received renewed attention after the identification of mutations in the cationic trypsinogen gene as being associated with hereditary pancreatitis. A survey of the literature revealed five cloned cDNAs, but only three protein products of human trypsinogens, and their nomenclature has been confusing. The availability of the complete genomic sequencing of the human trypsinogen gene family made it possible to provide a systematic review of the genes, cDNAs, and protein products of human trypsinogens and to clarify some controversial issues. Further, the confusing coexistence of two systems for naming the cationic trypsinogen mutations is addressed.

Hereditary pancreatitis and mutations of the cationic trypsinogen gene

BACKGROUND

Mutations of the cationic trypsinogen gene have been detected in hereditary pancreatitis. This article reviews current understanding of their function and clinical significance.

METHODS

An unrestricted Medline search was conducted using the key words hereditary pancreatitis and 'cationic trypsinogen . Additional material was obtained from references cited in original papers and recently published abstracts of meetings.

RESULTS AND CONCLUSION

Cationic trypsinogen mutations have been identified in most, but not all, families with hereditary pancreatitis. This confirms existing evidence that premature trypsinogen activation plays a central role in the pathogenesis of human pancreatitis. Patients currently clinically defined as having hereditary pancreatitis should be screened for the presence of cationic trypsinogen mutations. A subgroup of patients with non-hereditary pancreatitis may also benefit from being screened for these mutations. Patients with hereditary pancreatitis should be entered into prospective, multicentre trials investigating secondary screening for pancreatic cancer. Gene therapy for hereditary pancreatitis is beyond current technological capability but remains a future therapeutic prospect for this often debilitating condition.

Genetic predispositions to acute and chronic pancreatitis

Advances in molecular genetics have provided the powerful tools necessary to identify the key molecules and mechanisms that underly the disease process. Continued work in this area promises to reveal new insights as new disease genes are discovered. This article focuses on the insights into the cause of acute and chronic pancreatitis gained by investigation of the HP genes, the diagnosis of the known mutations, the fascinating observation of nonpenetrance, and a look at future directions.