Casting New Light on Genetic Iron Overload

Participants in a nutrition study who possessed a single mutated gene linked with iron overload did not absorb too much iron from foods in the study, compared to participants who didn't have the mutated gene. The finding is important because, as a public health policy, some U.S. foods are fortified with iron to aid consumers who wouldn't otherwise get enough from their diet.

Agricultural Research Service (ARS) nutritionist Janet R. Hunt and molecular biologist Huawei Zeng at the ARS Grand Forks Human Nutrition Research Center, Grand Forks, N.D., conducted the study. They wanted to find out whether carriers of a single copy of the genetic mutation could be at risk of absorbing too much iron. Hunt heads the center's Micronutrient Absorption and Metabolism Unit.

In people with hereditary hemochromatosis, also known as iron overload, excess iron is deposited in body organs, leading to diseases such as cirrhosis of the liver, diabetes, liver cancer and heart and joint diseases. Those who inherit two copies of the altered gene--one from each parent--have an increased risk of developing full-blown hereditary hemochromatosis. But approximately one in 10 people in the United States inherit just one of the altered genes, which makes them "silent carriers."

For this genotyping study, Hunt and Zeng tested 359 volunteers by taking DNA samples either from the inside of their cheeks or from their blood. Those identified as carrying a single copy of the mutation had their iron absorption measured after consuming regular and iron-fortified meals.

The findings suggest that iron fortification of foods does not pose a special health risk to the estimated 35 million carriers of one copy of the DNA mutation. May is "genetic screening awareness month" for the American Hemochromatosis Society, based in Orlando, Fla.

Read more about the research in the May 2005 issue of Agricultural Research magazine. ARS is the U.S. Department of Agriculture's chief scientific research agency.