Cystic fibrosis gene linked to pancreas disease

In this story:

• Cause of pancreas disease often unknown
• Just one bad gene may raise risk

BOSTON (AP) -- The same genetic defect that causes cystic fibrosis also appears to be involved in life-threatening inflammation of the pancreas, an ailment that afflicts about 100,000 Americans.

Two new studies provide the first solid evidence that chronic pancreatitis, as the disease is called, may be linked to a bad gene.

Researchers estimate that the cystic fibrosis gene may play a role in about 10 percent to 15 percent of these cases, even though victims show no signs of cystic fibrosis itself.

"This is a disease that until now nobody thought was inherited," said Dr. Jonathan A. Cohn of Duke University in Durham, North Carolina.

Cause of pancreas disease often unknown

By far the leading cause of pancreatitis is alcohol abuse. But in about 30 percent of cases there is no clear cause. The new work suggests that between one-third and one-half of these unexplained cases may be triggered -- at least in part -- by the cystic fibrosis gene.

Studies directed by Cohn and Dr. Nicholas Sharer of the Manchester Royal Infirmary in England were published in Thursday's issue of the New England Journal of Medicine.

The English group looked at 134 patients with pancreatitis, while Cohn's team examined 27. In both cases, doctors found a strong link between the cystic fibrosis gene and the disease, especially in those who were not alcoholics.

"We don't know what fraction of people who have these mutations actually have pancreatitis," Cohn said. "What we do know is that they are at higher risk than people without the gene, even though their overall risk is still probably very low."

About 30,000 Americans have cystic fibrosis. The disease occurs when people inherit two defective copies of a gene, one from each parent. The gene makes a protein called the cystic fibrosis transmembrane conductance regulator, or CFTR.

A hallmark of cystic fibrosis is excessive amounts of mucus in the bronchial tubes, which causes lung infections.

Just one bad gene may raise risk

The new studies suggest that having just one bad copy of the cystic fibrosis gene raises the risk of pancreatitis. This is a disease in which the tiny ducts in the pancreas become plugged with digestive juice.

About 10 million Americans are considered to be cystic fibrosis carriers because their genetic material contains one bad copy and one good copy of the CFTR gene.

Dr. Preston Campbell, medical director of the Cystic Fibrosis Foundation, said that parents of cystic fibrosis patients, who carry one copy of the gene, do not appear to be at unusually high risk of pancreatitis.

"It's important to point out that the majority of patients who carry one copy of the gene are at very low risk of chronic pancreatitis," he said.

Dr. Lawrence M. Silverman of the University of North Carolina, a co-author of Cohn's study, speculated that a second defect on an entirely different gene may be necessary to trigger pancreatitis in those who have a bad cystic fibrosis gene.