NEW YORK (Reuters) -- Less than 1% of people of European descent have an inherited iron metabolism disorder that can cause skin pigmentation, enlarged liver, liver cancer and possibly cardiac failure. To develop the disease, called hemochromatosis, individuals need to inherit two mutated genes -- one from each parent.
Now, a new study suggests that essentially healthy people who carry only a single mutated gene -- about 10% of whites -- may not necessarily need treatments for the excess of iron in their blood.
"This study establishes that, yes, such people have an abnormality of iron metabolism. But with very few exceptions, there is no health risk," said senior investigator Dr. James P. Kushner, of the Division of Hematology-Oncology at the University of Utah School of Medicine in Salt Lake City. "The only health risk was when there was a second associated disease, such as alcoholic liver disease or hepatitis."
Such diseases are made worse by even a moderate increase in blood iron levels, according to the report in this week's issue of The New England Journal of Medicine. Organ damage could be prevented if patients have their blood drawn at regular intervals.
In the study, researchers looked at more than 1,000 healthy men and women who carry a single gene for hemochromatosis. They found that 18% to 20% of the men, and 8% to 11% of the women, had elevated levels of iron and iron-transporting proteins in their blood. Six out of 39 liver biopsies showed liver damage, but those specimens were taken from individuals who also had complicating factors, such as alcoholism or hepatitis.
"The increased body iron burden in [those with one gene] appears to have minimal consequences," wrote Kushner. However, very few liver biopsies have been done on healthy people who carry one gene, he noted.
Hemochromatosis occurs when excessive amounts of iron -- which plays a key role in the formation of oxygen-transporting hemoglobin molecules -- is absorbed from the intestine. The iron builds up in the liver, heart and other organs, sometimes causing premature death due to liver disease, cancer or heart failure.
The disease "has been much underdiagnosed and misdiagnosed, in part because of an earlier belief that it was a variant of alcoholic cirrhosis, and also because its symptoms were confused with those of other diseases -- for example, alcoholic liver disease and arthritis," according to an editorial by Drs. Lawrie Powell and Elizabeth Jazwinska, of the Queensland Institute of Medical Research in Australia.
More study on those who carry one gene for the disorder may be useful to help determine which additional factors affect iron levels in those who actually carry the disease, the Australian researchers concluded.
SOURCE: The New England Journal of Medicine (1996;335:1799-1805)
