TUESDAY, Nov. 18 (HealthDayNews) -- A genetic mutation may cause the metabolic disorder primary iron overload, which is common among blacks.

The discovery is described in three studies in the November/December issue of Blood Cells, Molecules and Diseases.

Italian and American scientists report finding a variation in a gene called SCL40A1, which encodes the protein ferroportin 1, used by the body to transport iron.

Mutations in this gene lead to an increase in levels of the iron storage protein ferritin. This, in turn, results in an accumulation of iron in macrophages -- the body's scavenger cells.

"There are probably multiple causes (of primary iron overload disease), and we have found one of them," Dr. Ernest Beutler, chairman of the department of molecular and experimental medicine at the Scripps Research Institute, says in a prepared statement.

Beutler led one of the studies and co-authored a second.

Mutations in the SCL40A1 gene occur almost exclusively in black populations and may help explain the disproportionate number of black Americans who have primary iron overload.

In people with the disorder, excessive amounts of iron are deposited in the liver, pancreas and other organs. Primary iron overload can lead to diabetes, cirrhosis of the liver and cardiovascular disease. Severe forms of the disorder can be fatal.

More information

Here's where you can learn more about iron disorders.