U. PITTSBURGH (US) — A genetic variant on chromosome X near the claudin-2 gene (CLDN2) predicts which men who are heavy drinkers are at high risk of developing chronic pancreatitis, report scientists.
The finding, published online today in Nature Genetics, enables doctors to identify people with early signs of pancreatitis or an attack of acute pancreatitis who are at very high risk for progressing to chronic pancreatitis, allowing them to take preventative action to slow the development of the disease, and give the pancreas a chance to heal.
Once an individual develops pancreatitis it takes several years for the pancreas to deteriorate.
“The discovery that chronic pancreatitis has a genetic basis solves a major mystery about why some people develop chronic pancreatitis and others do not,” says David C. Whitcomb, professor of medicine, cell biology, and physiology, and human genetics at the University of Pittsburgh School of Medicine and lead author of the report.
“We also knew there was an unexpected higher risk of men developing pancreatitis with alcohol consumption, but until now we weren’t sure why. Our discovery of this new genetic variant on chromosome X helps explain this mystery as well.”
Over 100,000 Americans suffer from chronic pancreatitis, a progressive inflammatory disease characterized by abdominal pain and permanent damage to the pancreas.
Most studies report excessive alcohol consumption as the major risk factor for adult-onset chronic pancreatitis. However, according to Whitcomb, only 3 percent of individuals who are alcoholics develop chronic pancreatitis, suggesting a pancreas-specific risk factor.
No protection for men
The study was conducted over 10 years and involved more than 2,000 patients, all of whom underwent DNA testing in a study funded by the National Institutes of Health. Researchers discovered that there was a common DNA variant on the X chromosome that is present in 26 percent of men without pancreatitis, but jumps to nearly 50 percent of men diagnosed with alcoholic pancreatitis.
Women have two X chromosomes, so most women with the high-risk DNA variant on one X chromosome appear to be protected from alcoholic chronic pancreatitis by the other X chromosome, if it is normal. Men have one X chromosome and one Y chromosome, so if they inherit a high-risk X chromosome, there is no protection.
The factor on chromosome X does not appear to cause pancreatitis, but if pancreatic injury occurs for any reason such as gallstone pancreatitis or abdominal trauma, it is more likely that the person will develop chronic pancreatitis—especially if they also drink alcohol.
“This information is important because the high-risk chromosome can be identified in patients who drink and have early signs of pancreatic injury,” says Dhiraj Yadav, associate professor of medicine and a co-investigator on the study.
“If pancreatic injury and acute pancreatitis occur, patients must stop drinking immediately.”
Nationally, 16 percent of men drink alcohol at levels defined by the National Institute on Alcohol Abuse and Alcoholism as high risk. Twenty-six percent of these men who drink heavily are at high risk of chronic pancreatitis following pancreas injury. Only 10 percent of women drink alcohol at dangerous levels, and of these only 6 percent have the X chromosome variant on both X chromosomes.
“Previous discoveries show that chronic pancreatitis without alcohol involvement has a strong genetic link. This helps to eliminate the previous stigma that patients with chronic pancreatitis must also be heavy drinkers,” adds Whitcomb. “This study proves that there is a genetic element to the disease.”
Collaborators on this study contributed from the University of Pittsburgh, Pennsylvania State–Hershey, University of Liverpool, the University of Greifswald, and others. The research was supported by National Institutes of Health.
Source: University of Pittsburgh