Genetic Haemochromatosis

Genetic haemochromatosis is a disorder, which causes iron build up over time. Usually an adult has about 4 grams of iron in their body but with this disorder the amount of iron in the body is much higher, with the total amount of iron in the body reaching up to 20 to 40 grams if untreated.

In Australia, haemochromatosis affects 1 in 200-300 people but it is most common in Australians whose ancestry is from Northern Europe or the United Kingdom.

If haemochromatosis is left untreated, it leads to conditions such as:

§ Cirrhosis of the liver

§ Cardiomyopathy

§ Diabetes

To prevent these problems from developing, early diagnosis and treatment is needed. The treatment for this disorder is done by regularly extracting blood, from the same main vein, as the one that's used for when a person donates blood. By doing this regularly, it reduces the high levels of iron in the blood so that it doesn't get stored in various organs.

People who are affected by haemochromatosis may show no symptoms at all. The symptoms of this disorder are more likely to develop in men aged between 40 and 60 years old and at a later age for women, although the disorder can be diagnosed much earlier. For this disorder, symptoms vary according to the organs involved. In the early years there may be no symptoms at all except for a healthy skin colouring that seems like a tan. Although early symptoms that occur in some people are:

§ Weakness

§ Weight Loss

§ Lack of interest or concern

§ Sexual drive

§ Pain in the arms

§ Muscle Tenderness

§ Cramps in the legs

Symptoms may occur earlier in men though because women lose blood during menstruation and childbirth causing the iron levels in the body to reduce.

THE CAUSES OF HEREDITARY HAEMOCHROMATOSIS

The gene most commonly involved in hereditary haemochromatosis is called the HFE gene. On the short arm of chromosome number 6 is where this gene is located. The HFE gene codes the protein that regulates iron absorption. When the HFE gene is faulty the message from the gene is also faulty causing the iron storage that regulates itself to fail.

Two mutations, called C282Y and H63D, have been identified in the HFE gene. It appears to cause most of the cases of hereditary haemochromatosis.

Being born with two faulty HFE gene copies does not actually have to mean that a person will definitely develop HH, it just means that they are more easily affected by hereditary haemochromatosis then others. There are also other triggering factors that are important in the development of HH and also how easily it's affected, are different for males and females. Also by having a H63D mutation in both copies of their HFE gene rarely causes a person to develop HH. There is also a difference in men and women how this disorder can affect them. It is estimated that 90% males and 50-70% females born with the C282Y mutation in both copies of the HFE gene, will develop HH at some time during their life. About 90% of people with symptoms of HH have the mutation called C282Y in both copies of their HFE gene. Although only 2% of people with HH have a C282Y mutation in one of their HFE gene copies and a mutation called H63D in their other HFE gene copy. When a person is born with these two faults in their HFE gene copies, less than 1% will develop the symptoms of hereditary haemochromatosis during their lifetime. To end these statistics, about 10% of people with symptoms don't have either of these mutations in their HFE gene.

GENETIC CARRIERS FOR HH

Everyone has two copies of the iron storage-regulating gene (the HFE gene) in their body's cells. People who have a correct copy of the gene and a mutated copy are called "carriers" of the mutated gene for HH (genetic carriers). They would hardly show any symptoms, or have only a very slight form of the disease since they have one correct copy of the gene, which usually regulates the amount of iron stored in the body. Triggering factors such as having diabetes or being an alcoholic, for genetic carriers can develop the disease.

THE PATTERN OF INHERITANCE OF HEREDITARY HAEMOCHROMATOSIS IN FAMILIES

HH being a recessive genetic disorder follows a pattern of inheritance in families.

In Figures 1 and 2, the little 'r' and the correct copy by using the big 'R', represent the mutated iron storage regulation gene.

There are four different ways for the combination of genes to be able to be passed from parents to children.

Shown in Figure 1, is if a couple who are both carriers of the mutated gene have a baby, then there is a 25% chance in every pregnancy, that they'll have a baby who is likely to develop HH as an adult.

In Figure 2, it's a bit different. If only one parent is a carrier of the mutated gene, there is a 50% chance that their children will be genetic carriers. There isn't any chance that their children will inherit two faulty copies of the