Identification of a hereditary pancreatitis mutation in four West Virginia families

A case of MERRF associated with chronic pancreatitis

We report the first case to our knowledge of chronic pancreatitis associated with mitochondrial encephalopathy with the A8344G mitochondrial DNA (mtDNA) mutation. This 10-year-old-girl had suffered from recurrent abdominal pain with elevated serum amylase and lipase since the age of 6, and easy fatigability, tremor and astatic seizures since the age of 8. A biopsy of quadriceps muscle revealed ragged-red-fibers and cytochrome c oxidase deficiency. Analysis of mtDNA in peripheral blood identified an A8344G mutation in the mitochondrial tRNA(Lys) gene. Taken together with physical signs of myoclonic seizures and cerebellar dysfunction, we diagnosed her as myoclonic epilepsy with ragged-red fibers associated with chronic pancreatitis. Although no association between mitochondrial disease and pancreatitis has yet been established, this case suggests it is necessary to consider the participation of mitochondrial abnormality in the pathogenesis of recurrent pancreatitis.

Chronic pancreatitis

In the past year, there has been at least one important clinical paper that sheds light on the character and natural history of painful chronic pancreatitis, which has important clinical implications. In addition, several novel mutations have been described in the cationic trypsinogen gene in patients with hereditary pancreatitis. The mechanism by which these mutations cause pancreatic disease remains speculative. The diagnosis of early chronic pancreatitis is controversial. A novel noninvasive pancreatic function test (measurement of postprandial APOB-48) was reported but is unlikely to be a sensitive test of pancreatic function. Pancreatic fibrosis is frequently seen in alcoholics without chronic pancreatitis, and this makes it difficult to interpret the findings on endoscopic ultrasonogram. Recent studies highlight the difficulty in abolishing pancreatic steatorrhea. Recently fibrosing colonopathy in adult patients has been reported. Extracorporeal shockwave lithotripsy combined with endoscopic therapy failed to benefit patients with calcific chronic pancreatitis.

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.