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Haemochromatosis is defined as iron overload leading to end organ damage. As the body does not have a way to excrete excess iron, there is a progressive build-up of iron in tissues and organs. The excess iron is stored in your organs, especially the liver, heart and pancreas. This can lead to organ dysfunction and failure. As it progresses, complications can include arthritis, diabetes, liver cirrhosis, heart arrhythmias and failure, loss of libido and a charateristic metallic grey pigmentation of the skin.
This condition may be inherited which is called hereditary haemochromatosis (HH) or acquired, which is caused by some other disease or underlying condition. The most common form is an inherited disorder.
Hereditary haemochromatosis (HH)
This is seen mainly in white skinned people (Caucasians). HH is also the most common genetic disorder in Australia, affecting about one in every 200 Australians of European origin. It causes the body to absorb too much iron resulting in iron overload.
Iron is absorbed from the diet through the small intestine and the amount absorbed is determined by the body's needs. People with HH absorb more iron than their body needs. As the body does not have a way to increase excretion of the excess iron there is a progressive build-up of the excess iron in tissues and organs.
Early iron overload might have no symptoms, even though organ damage is occurring. Symptoms tend to occur after the age of 40, but may be earlier or later. Early symptoms may include fatigue, abdominal pain and joint aches
The HFE gene
HH is an autosomal recessive disorder. Everyone has two copies of the HFE gene- one inherited from their mother and the other one inherited from their father. HH is usually caued by a mutation in the HFE gene. To have HH a person needs to have a fault in both their HFE genes.
The most common mutation is called C282Y. Other mutations are called H63D ( the second most common) or S65C. Two copies of C282Y or a copy of C282Y together with a copy of H63D or S65C, places a person at risk for HH. About 1 in 200 Caucasians of Northern European descent have two abnormal (mutated) copies of the gene associated with HH and are at risk for developing iron overload and clinical symptoms. However, not all the people with two copies of the mutated gene develop HH. It is estimated that up to 45% of men and 10% of women who have a double dose of the C282Y gene fault will develop significant problems ushc as liver cirrhosis. Clinical disease is less common in females due to physiological blood loss from menstruation and pregnancy. More than 80% of cases of HH are due to C282Y homozygosity (carrying two copies of the C282Y gene). Around 80% of men and 60% of women with the double dose of the C282Y gene fault will havve raised iron levels in their body. The reason why some have ery high iron levels and severe medical problems whilst others have midler or even no problems, is not yet understood.
In Australia, around 1 in 5 people have a singe copy of the H63D gene fault and 1 in 9 a single C282Y gene fault. People with one abnormal (mutated) copy of the HFE gene, are referred to as carriers. Carriers are not at particular risk for developing iron overload. The carrier status is much lower in other racial/ethnic groups.
This is due to a variety of other diseases and conditions. Examples include:
- Chronic liver disease, such as chronic hepatitis C infection, alcoholic liver disease, or non-alcholic steatohepatitis (NASH)
- Alcohol abuse
- Multiple blood transfusions e.g. for the treatment of thalassaemia
- Some haemolytic diseases
- Rarely excessive oral iron supplementation
Last Review Date: June 8, 2019
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