What Causes Hemochromatosis?

There are two types of hemochromatosis: primary (hereditary) and secondary. Each type has a different cause.

Primary Hemochromatosis

A defect in the genes that control how much iron you absorb from your diet causes primary hemochromatosis. Primary hemochromatosis is sometimes called hereditary hemochromatosis or classical hemochromatosis. Most cases of hemochromatosis are primary hemochromatosis.

The genes most commonly involved in primary hemochromatosis are called HFE genes. Abnormal HFE genes cause the body to absorb too much iron. Humans inherit two copies of most of the genes in the body, one from each parent. You have primary hemochromatosis if you inherit two copies of the abnormal HFE gene, one from each parent.

If you inherit one abnormal HFE gene and one normal HFE gene, you are a hemochromatosis "carrier." Carriers do not usually develop the disease, but they can pass the abnormal gene on to their children. About 1 in 10 people in the United States are believed to be hemochromatosis carriers.

If both parents are carriers of the abnormal HFE gene, then each of their children has a 1 in 4 chance of inheriting a pair of abnormal HFE genes.

Other types of abnormal genes also can cause hemochromatosis, but less commonly. Scientists are still studying what other changes to normal genes may cause hemochromatosis.

Secondary Hemochromatosis

This type of hemochromatosis is usually the result of another disease or condition that can cause iron overload. Diseases or conditions that may cause hemochromatosis include:

• Certain anemias, such as thalassemia and aplastic anemia
• A condition called African iron overload, which is a combination of an inherited disorder and diet
• Atransferrinemia and aceruloplasminemia, both rare inherited diseases
• Chronic liver disease, such as hepatitis, alcoholic liver disease, or nonalcoholic steatohepatitis ("steato" means "fatty")

Secondary hemochromatosis can sometimes be caused by too much iron from:

• Blood transfusions
• Iron intake (from oral iron pills or injected iron)
• Long-term kidney dialysis