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Hemochromatosis
Hereditary hemochromatosis is the genetic form of hemochromatosis, a disease characterized by a progressive iron overload.
It affects about one million individuals in the US. In hereditary hemochromatosis, more iron is absorbed than is needed. With the exception of menstruation in women, the human body has no natural means of getting rid of extra iron. As a result, iron builds up in individuals with hereditary hemochromatosis and is deposited throughout the body. Over time iron can reach toxic levels in tissues, causing dysfunction and failure in major organs such as the liver, pancreas, heart, thyroid, pituitary gland, and joints.
Hereditary hemochromatosis can have a variety of symptoms, ranging from mild conditions like fatigue, weakness, abdominal and joint pain to more severe ones associated with failures in the aforementioned organs. Undiagnosed and untreated, hereditary hemochromatosis can have serious consequences over time, including increased risk for liver diseases, heart problems, arthritis, depression, impotence, infertility, hypothyroidism, pituitary hormone deficiency, diabetes and even some forms of cancer.
The worldwide prevalence of hereditary hemochromatosis in 18-70 year old individuals is estimated to range from 1.5 to 3 per 1000 individuals. However, the disease is thought to be significantly under-diagnosed and is more common in men than in women. The prevalence of hereditary hemochromatosis also varies considerably between populations, being most common in individuals of European descent.
Hereditary hemochromatosis actually has a geographic distribution that is thought to reflect the historical movements of people of northwestern Europe. It is most frequent in populations surrounding the North Sea; Norway, Denmark, Iceland, Germany (west and south), France, the United Kingdom, and Ireland. It isless frequent in southern Europe, and almost non-existant in Africa. In the United States, the frequency in individuals of European descent is similar to that seen in northern Europe. The highest frequency of the disease is found in the Irish population. This and the geographic distribution of the disease, has led scientists to believe that hemochromatosis is the result of a relatively recent mutation originating in a Celtic population (indeed, hereditary hemochromatosis is sometimes referred to as the “Celtic curse”). Some scientists have however proposed that the mutation is of Viking or Germanic origin.
Hereditary hemochromatosis is caused by mutations in the HFE gene on chromosome 6. There are more than 20 known mutations in the HFE gene, but the most important for hereditary hemochromatosis identified to date are two sequence variants, C282Y and H63D. The C282Y mutation explains 80 to 90 percent of all diagnosed cases of hereditary hemochromatosis in populations of northwestern European ancestry.
The deCODEme Genetic Scan identifies the C282Y and H63D sequence variants in the HFE gene on chromosome 6 and uses them to provide customers of European descent with a personalized interpretation of their genetic risk for developing hereditary hemochromatosis.
At present, the necessary scientific information to interpret the genetic risk for customers of other ethnicities is not available. This information will be added as soon as it becomes available and we are assured of its quality.
- [1] Lucotte G, Dieterlen F. Blood Cells Mol Dis. 2003 31(2):262-7.
This content was last reviewed on February 11, 2010.
