CausesBy Mayo Clinic staff
Hereditary hemochromatosis is caused by a mutation in a gene that controls the amount of iron your body absorbs from the food you eat. The mutations that cause hereditary hemochromatosis are passed from parents to children.
Gene mutations that cause hemochromatosis
The gene that is mutated most often in people with hereditary hemochromatosis is called HFE. You inherit one HFE gene from each of your parents. The HFE gene has two common mutations, C282Y and H63D. One of these mutations is found in about 85 percent of people who have hereditary hemochromatosis. Genetic testing can reveal whether you have these mutations in your HFE gene.
- If you inherit 2 abnormal genes, you may develop hemochromatosis. About 70 percent of people who inherit two genes develop evidence of iron overload of hemochromatosis. You can also pass the mutation on to your children.
- If you inherit 1 abnormal gene, you won't develop hemochromatosis. You are considered a gene mutation carrier and can pass the mutation on to your children. They would not develop disease unless they also inherit another abnormal gene from another parent.
How hemochromatosis affects your organs
Iron plays an essential role in several body functions, including helping in the formation of blood. A peptide hormone called hepcidin, secreted by the liver, plays a key role in the body's use of iron. It controls how much iron is absorbed by the intestines, how iron is used in various body processes and how it's stored in various organs.
In hemochromatosis, the normal role of hepcidin is disrupted and your body absorbs more iron that it needs. This excess iron is stored in the tissues of major organs, especially your liver. Too much iron is toxic to your body, and over a period of years, the stored iron can severely damage many organs, leading to organ failure and chronic diseases such as cirrhosis, diabetes and heart failure.
Though many people have faulty genes that cause hemochromatosis, only about 10 percent of them have iron overload to the degree that causes tissue and organ damage.
Other types of hemochromatosis
- Juvenile hemochromatosis. This causes the same problems in young people that hereditary hemochromatosis causes in adults. But iron accumulation begins much earlier, and symptoms usually appear between the ages of 15 and 30. This disorder is caused by a mutation in the HJV gene.
- Neonatal hemochromatosis. In this severe disorder, iron builds up rapidly in the liver of the developing fetus. It is thought to be an autoimmune disease, in which the body attacks itself.
- Secondary hemochromatosis. This form of the disease is not inherited. The iron deposits are due to another disease, such as anemia, chronic liver disease or an infection.
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- What is hemochromatosis? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/hemo/. Accessed Nov. 7, 2012.
- Eng KG, et al. Natural history and management of HFE-Hemochromatosis. Seminars in Liver Disease. 2011;31:293.
- Hemochromatosis. National Institute of Diabetes and Digestive and Kidney Diseases. http://digestive.niddk.nih.gov/ddiseases/pubs/hemochromatosis/index.htm. Accessed Nov. 12, 2012.
- Poterucha JJ (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 29, 2012.