May 12, 2009

Study: Genetics involved in gallstone risk

Although obesity and gallstones often go together, U.S. scientists say genetically modified mice fed high-fat food don't grow fat, but do develop gallstones.

Washington University School of Medicine researchers in St. Louis said they studied a strain of mice genetically engineered to lack a substance called liver fatty acid binding protein. The scientists compared the modified mice with their healthy, normal littermates.

Both groups ate either a standard chow diet or a diet that provided about 20 percent of its calories in the form of fat and cholesterol.

Mice lacking the protein didn't become obese on the high-fat diet as did the normal mice. But while they remained lean, the engineered mice developed gallstones at high rates.

Gallstones form when cholesterol is secreted in bile from the liver at high concentrations, and that typically happens in patients who are obese, who have diabetes, take estrogens or who have lost a lot of weight very rapidly, said Dr. Nicholas Davidson, who led the study. Since these mice don't become obese, we thought they might be protected against gallstones. But we found that they were dramatically more susceptible.

He said the experiments show genetic factors are involved in gallstone risk.

The research appears in the Journal of Lipid Research.