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Hemochromatosis Gene

Mutations in the Gene for Hemochromatosis

Researchers have identified more than 20 mutations in the HFE gene that cause hereditary hemochromatosis. These genetic mutations alter the size of the HFE protein or disrupt its three-dimensional shape. As a result, the HFE protein cannot function properly.
Two particular mutations are responsible for most cases of hereditary hemochromatosis. Each of these mutations changes one of the building blocks (amino acids) used to make the HFE protein. These two important mutations are found at the C282Y and H63D portion of the HFE gene.
C282Y is the most important HFE mutation. When two mutated copies of C282Y are inherited (one from each parent), iron is overabsorbed from the diet and hemochromatosis can result. When a person inherits two mutated copies of H63D, there is usually little increase in iron absorption. However, a person who inherits one HFE mutation at H63D from one parent and one mutation at C282Y from the other may rarely develop hemochromatosis.

Inheriting the Hemochromatosis Gene

A child who inherits two copies of a mutated gene for hemochromatosis (one from each parent) is highly likely to develop the condition. However, not all people who have two mutated copies of the gene develop signs and symptoms of hemochromatosis.
In fact, research scientists are not exactly sure what percentage of people who have two copies of the mutated HFE gene develop the disease. Some studies have shown that as few as 1 in 100 people will develop symptoms. Other studies have shown that as many as 50 in 100 people may develop symptoms of hemochromatosis.
People who inherit only one copy of the mutated gene are hemochromatosis carriers, but usually have no associated symptoms, or have very mild symptoms, since one correct copy of the gene appears to adequately regulate iron absorption. "Silent" carriers, those without symptoms of hemochromatosis, can still pass on the defect to their children.
If two parents are silent carriers, a child has a 25 percent chance of inheriting two copies of the defective hemochromatosis gene, and will most likely develop the disease. An estimated 10 percent of the U.S. population carries the gene. Carriers are most likely to exhibit signs of hemochromatosis if there are triggers, such as diabetes or alcoholism.

Hemochromatosis Disease

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