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FAQ ON GENETIC HAEMOCHROMATOSISThis answer is brought to you by many of the Australian nutrition professionals who regularly contribute to the Nutritionists Network (‘Nut-Net'), a nutrition email discussion group. Date of last revision: December 2004 Lack of iron in the body is the world's most common nutritional deficiency. Approximately two billion people (one third of the world's population) suffer from anaemia because they do not get enough iron in their diet. But paradoxically, despite having only a normal dietary intake of iron, some people suffer from the exact opposite problem—too much iron in their bodies. This condition is known as ‘haemochromatosis' (also spelled ‘hemochromatosis'). Normally, only a small proportion (about 5–20%) of ingested iron is absorbed from the intestine into the body. People who have the haemochromatosis gene absorb a greater proportion of iron than usual. Those people who have just one copy of the gene (together with one normal gene) absorb a little more iron than those who have two copies of the normal gene. But people who have two copies of the haemochromatosis gene (and therefore do not have a copy of the normal gene) absorb even more. Absorbing high levels of iron from the diet can be an advantage if you are iron-deficient, but the problem with haemochromatosis is that the high level of absorption does not stop when adequate iron has been absorbed. As the levels of iron build up in the body, the likelihood of harm increases. Whereas a healthy person's body may contain up to one gram of iron (enough to make a small nail), a person with haemochromatosis may acquire 3 or 4 grams, and in extreme cases even up to 20 grams of iron, which may be enough to set off metal detectors at airports! Because it is genetic in origin, this condition is not ‘curable', but it can be controlled with appropriate medical treatment and some simple dietary alterations. Question 1. What effects does haemochromatosis have and how common is it? Iron is the critical component of ‘haemoglobin', the red pigment in blood. Haemoglobin carries oxygen to the tissues, so iron is essential in the diet. In good health some iron is stored in the liver before being used to make haemoglobin, but as explained above, haemochromatosis leads to excessive absorption of iron from the diet. Much of the additional iron is deposited in the liver, damaging this vital organ and causing it to enlarge. Harmful levels of iron may also be deposited in other organs, including the heart and pancreas. It can also affect joints, leading to symptoms similar to arthritis. The extent of genetic haemochromatosis in Australia is not exactly known. One study estimated that about one Australian in 80 has the condition, many without knowing it. It can affect men, women and children at any age. Genetic haemochromatosis is particularly common among people whose ancestors came from Britain or elsewhere in northern Europe. The genetics of haemochromatosis is rather complicated—see the Appendix to this FAQ for more details on how it is inherited. Because of the seriousness of the condition, and its hereditary nature, if you or any of your relatives are diagnosed with genetic haemochromatosis, other members of your immediate family should be tested as a matter of some urgency. If you have symptoms that are suggestive of haemochromatosis (see next section), you should raise the possibility with your doctor that a possible cause is genetic haemochromatosis. Question 2. So what exactly are the symptoms of haemochromatosis ? Because the excess iron can be stored almost anywhere in the body, haemochromatosis can lead to a huge range of symptoms, making a diagnosis difficult. A blood test is the only way to be sure that haemochromatosis is (or isn't) causing the health problems. The symptoms can include any (and usually more than one) of the following:
In addition, having haemochromatosis may cause men to experience impotence, while women may suffer from early menopause and/or irregular periods. People with haemochromatosis may also suffer infectious diseases at a greater rate than usual, because high levels of blood iron reduce the body's immunity to disease. As previously mentioned, another possible indicator is setting off airport metal detector alarms for no apparent reason. It needs to be kept in mind that many of these symptoms are also indicative of other disorders. As examples, chronic fatigue may occur after a viral infection, or may be due to depression; abdominal pain can be caused by irritable bowel syndrome (among other conditions); and cirrhosis of the liver often occurs in people who have excessive intakes of alcohol. However, someone who suspects that they may have the genetic potential to develop haemochromatosis (e.g., a close relative has been diagnosed) should not wait until symptoms occur. There is always the risk that a severe condition—such as cirrhosis of the liver—may occur before actual symptoms show, so early diagnosis and treatment are critical in reducing the potential for long-term harmful effects. Question 3. With so many possible symptoms, how is haemochromatosis diagnosed? Initially, it is more important to determine the presence of excess iron in the body (i.e., haemochromatosis) rather than establishing a diagnosis of genetic haemochromatosis. That is, to start necessary treatment, the doctor only needs to know that a patient has potentially harmful levels of excess iron, not how the excess came about. To test how much iron there is in the body, your doctor will take a small blood sample and have it analysed for ‘serum ferritin'. If this test shows a high level of iron, treatment can then be commenced while further tests are conducted to see if the iron overload is the result of genetic haemochromatosis. These tests may include a liver biopsy to determine if damage has already occurred to the liver (e.g., cirrhosis), and a gene test—which is a simple blood test for the genetic mutation. This gene test is positive in over 90% of those affected by haemochromatosis, allowing identification of family members at risk of iron overload. It is recommended that you receive genetic counselling from your doctor or geneticist before undergoing any genetic testing. Question 4. What is the treatment for haemochromatosis? The major treatment is removal of blood, by the same method as that used to make a blood donation. This is called ‘venesection' or ‘phlebotomy'. When blood is removed by phlebotomy, some iron is released from storage sites in the body to replace the lost iron. If this is repeated often enough—once or twice weekly is usually adequate—the amount of iron stored in the body will gradually diminish. After about two years, the frequency of phlebotomies can often be substantially reduced, because the excess iron has been removed. However, because the condition cannot be ‘cured' (it is genetic in origin), the tendency will always be to store more iron. This means that, even after the body's excess iron stores have been depleted, phlebotomies will have to be continued for the rest of the person's life, although at a much reduced rate (usually only at intervals of three or four months). Question 5. How effective is treatment? While regular taking of blood will allow the body's iron stores to return to normal, it will not cure some severe conditions if these have already been triggered by the high iron levels. These include diabetes mellitus and cirrhosis of the liver. This indicates the importance of early detection so treatment can be commenced before serious, complicating illnesses occur. Less serious conditions—such as chronic fatigue, yellowing of the skin and abdominal pain— should improve once the body's iron levels are brought under control. Unfortunately, impotence, irregular menstruation and arthritis may not improve. But early diagnosis and continued treatment will usually mean a normal life expectancy. Question 6. Is there a special diet for haemochromatosis? Although iron intake in the diet should be controlled, diet alone cannot treat the iron overload resulting from haemochromatosis. Phlebotomy is the major treatment. In any case, many foods that are rich in iron are nutritious in other ways, so a low-iron diet is not usually recommended. However, some dietary precautions are appropriate, for example vitamin C supplements should not be taken, because vitamin C enhances the absorption of dietary iron into the body. Raw seafood should also be avoided, as should breakfast cereals that are fortified with iron. Meat and offal are rich in iron, so consumption of these foods should be restricted (one small serve of meat per day is adequate). Some foods are helpful, for example tea and milk products interfere with iron absorption, so these are appropriate drinks to have with meals (while alcohol may increase iron absorption, so its intake should be restricted). Further Reading Haemochromatosis: A Common Inherited Disorder Obtainable from 412 Musgrave Road Coopers Plains Qld 4108 (Postal Address PO Box 154 Coopers Plains Qld 4108) Phone: 07 3345 8051 Web address: http://www.haemochromatosis.org.au/ Appendix: Inheritance Of Genetic HaemochromatosisIn 1996 the major gene for haemochromatosis was discovered. The gene is known as a ‘recessive' gene, meaning that two copies of the defective gene must be present before it is likely to cause severe iron overload. A person with just one copy of the haemochromatosis gene, together with a copy of the normal gene, will be a ‘carrier', and so can pass the condition on to the next generation. But that person will not usually experience a harmful level of iron overload (although in rare instances this can occur). One Australian study found that about one-third of the population are carriers (i.e., have one gene for haemochromatosis and one for normal blood absorption) meaning that about 11% of marriages will be between carriers. On average, about one-quarter of the children in these families might be expected to develop haemochromatosis. If one parent actually has genetic haemochromatosis and the other parent is a carrier, on average about half the children in that family will develop haemochromatosis, while the other half will be carriers. In the unusual situation that both parents have genetic haemochromatosis, all the children will develop the condition. Back to Frequently Asked Questions Index |