African Iron Overload
NORD is very grateful to Pradyumna D. Phatak, MD, FACP, Medical Director, Lipson Cancer/Blood Center, Rochester General Hospital, and Clinical Professor of Medicine, UR School of Medicine, for assistance in the preparation of this report.
Synonyms of African Iron Overload
- African siderosis
- Bantu siderosis
- No subdivisions found.
African iron overload is a rare disorder characterized abnormally elevated levels of iron in the body. The name originates from the initial description of this entity in sub-Saharan Africa, in communities where affected individuals drink a traditional, homemade beer that contains a high amount of iron. Symptoms may vary from case to case but can include the accumulation of fibrous tissue (fibrosis) in the liver and, eventually, scarring of the liver (cirrhosis). The exact cause of African iron overload is unknown, but researchers believe that a combination of dietary and genetic factors result in the development of the disorder.
Researches originally believed that the popular, iron-rich beer caused cases of African iron overload. However, many individuals that drank the beer did not develop the disorder and some individuals that did not drink the beer did develop it. This led researchers to speculate that a mutation of a gene or genes involved in the transport or breakdown (metabolism) of iron must play a role in the development of African iron overload. Such a gene has not yet been identified.
The symptoms of African iron overload can vary from one person to another. The disorder usually develops in middle-aged or older adults. Affected individuals often develop abnormal enlargement of the liver (hepatomegaly). In more serious cases, the accumulation of fibrous tissue (fibrosis) in the main vein that supplies blood to the liver (portal vein) may result in high blood pressure in the this vein (portal hypertension). Abnormal fluid retention in the abdominal cavity can cause swelling (ascites). In some cases, scarring of the liver (cirrhosis) and, potentially, liver failure may eventually occur.
Additional symptoms have been reported to occur in association with African iron overload depending upon the extent of and exact location of iron accumulation. For example, diabetes may occur because of iron accumulation in the pancreas, the small organ located behind the stomach that produces insulin. Diabetes is a common disorder in which the body does not produce enough or is unable to properly use insulin.
Additional conditions that have been associated with African iron overload include bone thinning (osteoporosis), heart (cardiac) abnormalities, and an increased susceptibility to developing infections such as tuberculosis. Individuals with African iron overload are at a greater risk than the general population of developing esophageal cancer or a primary cancer of liver known as hepatocellular carcinoma.
African iron overload was originally believed to be caused in individuals who had a diet high in iron, especially individuals in rural African communities that drank a homemade beer with high amounts of iron. However, many individuals in these regions who did not drink excessive amounts of this iron-rich beer also developed African iron overload. Researchers now believe that African iron overload is caused by mutations of an as yet unidentified gene or genes and can be worsened by a diet high in iron.
The most common and best studied form of inherited iron overload is classical hereditary hemochromatosis, which is caused by mutations of the HFE gene. In the past few decades, researchers have identified separate forms of hemochromatosis and iron overload disorders that occur due to mutations of other iron-related genes. Studies have determined that African iron overload is not related to HFE mutations or to any of these other described mutations. More research is necessary to identify the genetic factors that may contribute to the development of this disorder.
African iron overload affects males and females in equal numbers. The exact incidence of the disorder is unknown. It has been reported in numerous countries in sub-Saharan Africa. Researchers believe that the disorder often goes unrecognized and is underdiagnosed, making it difficult to determine its true frequency in the general population. Some estimates suggest that iron overload affects more than 10 percent of the population in sub-Saharan Africa.
Inherited forms of iron overload have been reported in natives of other countries who may be of African descent (e.g. African Americans). Whether this may represent the same disease as that seen in sub-Saharan Africa remains unknown.
Symptoms of the following disorders can be similar to those of African iron overload. Comparisons may be useful for a differential diagnosis.
Primary disorders of iron overload are a group of primarily rare disorders characterized by iron accumulation in the body. This group includes hemochromatosis, atransferrinemia, and neonatal hemochromatosis. Hemochromatosis has been separated into four distinct disorders - hereditary (classic) hemochromatosis, also known as HFE-related hemochromatosis (which is not rare); hemochromatosis type 2 (juvenile hemochromatosis); hemochromatosis type 3, also known as TFR-related hemochromatosis; and hemochromatosis type 4, also known as ferroportin disease. The specific symptoms related to these disorders can vary depending upon the location and extent of iron accumulation. Common symptoms include fatigue, abdominal pain, lack of sex drive, joint pain, and heart abnormalities. If left untreated, iron can build up in various organs in the body causing serious, life-threatening complications. (For more information on these disorders, choose the specific disorder name as your search term in the Rare Disease Database.)
A diagnosis of African iron overload is made based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and a variety of specialized tests such as blood tests, which can reveal elevated levels of ferritin in the blood plasma. Ferritin is a protein that binds to iron and is used as an indicator of the body’s iron stores. Another test measures transferrin saturation. Transferrin is a protein involved in the transport of iron from the intestine into the bloodstream.
Therapy involving the regular removal of blood via a vein (known as a venesection or phlebotomy) is a common therapy for disorders associated with excess iron in the blood and should be beneficial to individuals with African iron overload. Controlled clinical studies of therapeutic phlebotomy for individuals with African iron overload have not been done yet but phlebotomy, if tolerated, is considered by many to be the standard of care.
Genetic counseling may be of benefit for affected individuals and their families.
Additional therapies have been used to treat individuals with disorder of iron overload. Such therapies include iron chelators. Iron chelators are drugs that bind to the excess iron in the body allowing it to be dissolved in water and excreted from the body through the kidneys. More research is necessary to determine the long-term safety and effectiveness of such therapies for individuals with iron overload diseases such as African iron overload.
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African Iron Overload Resources
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FROM THE INTERNET
Iron Disorders Institute. African Siderosis. November 3, 2006. Available at: http://www.irondisorders.org/Disorders/Siderosis.asp Accessed On: April 30, 2012.
McKusick VA., ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:601195; Last Update:10/26/2002. Available at: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=601195 Accessed on: April 30, 2012.
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Report last updated: 2013/03/12 00:00:00 GMT+0
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