Hereditary pancreatitis in North America: the Pittsburgh-Midwest Multi-Center Pancreatic Study Group Study

Abstract

Background: Hereditary pancreatitis (HP) was defined on a clinical basis alone until the first cationic trypsinogen gene (PRSS1) mutation was discovered through the initial phase of the current Pittsburgh Midwest Multi-Center Pancreatic Study Group (MMPSG) HP study in 1996, making genetic testing available.

Aim: To evaluate the regional distribution of HP in the United States, and to compare the study's gene mutation database with the pedigree databases to determine whether family history alone predicts the likelihood of detecting mutations in the cationic trypsinogen gene.

Methods: Probands of families with HP, familial pancreatitis and idiopathic chronic pancreatitis were recruited through referrals from MMPSG collaborating centers, other physicians and self-referral of patients who had learned of the study through the World Wide Web (www.pancreas.org). Pedigrees were constructed, detailed questionnaires were completed and a blood sample was drawn for each proband and participating family members. The birthplace and current location of each patient was recorded, DNA was analyzed for known mutations and the pattern of phenotype inheritance was determined from analysis of each pedigree.

Results: A total of 717 individuals were ascertained; 368 (51%) had clinical pancreatitis confirmed and the rest were primarily unaffected family members used for linkage studies. Forty-six clinically unaffected individuals were silent mutation carriers (11% of mutation-positive individuals). HP was most common in Minnesota, New York and the central mid-Atlantic states plus Kentucky and Ohio. One hundred and fifteen of 150 kindreds fulfilled the strict definition of an HP family, and 60 (52%) had PRSS1 mutations. Of the families with a detected mutation, 11% did not fulfill the clinical definition of an HP kindred.

Conclusions: The distribution of HP within the United States shows major regional differences. The etiology of HP can be identified in a small majority of HP families through genetic testing. However, family history alone is not a good predictor of finding a mutation in the cationic trypsinogen (PRSS1) gene.