Hereditary haemochromatosis: Difference between revisions
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'''Haemochromatosis''', also spelled '''hemochromatosis''', is a [[hereditary disease]] characterized by improper processing by the body of [[iron]] from foodstuffs. |
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It results in the progressive accumulation of iron in the body. By midlife sufficient iron may have been absorbed to damage the [[liver]], [[pancreas]] and [[testes]] to cause failure of these organs. [[Cirrhosis]], [[liver cancer]], [[diabetes]] and [[impotence]] may result. A form of [[arthritis]] develops in many patients. There is also susceptibility to serious infectious diseases; one such infection may occur after eating raw [[oyster]]s. Females are relatively protected against these abnormalities, at least until after [[menopause]], because of the loss of iron with [[menstruation]] and [[pregnancy]]. |
It results in the progressive accumulation of iron in the body. By midlife sufficient iron may have been absorbed to damage the [[liver]], [[pancreas]] and [[testes]] to cause failure of these organs. [[Cirrhosis]], [[liver cancer]], [[diabetes]] and [[impotence]] may result. A form of [[arthritis]] develops in many patients. There is also susceptibility to serious infectious diseases; one such infection may occur after eating raw [[oyster]]s. Females are relatively protected against these abnormalities, at least until after [[menopause]], because of the loss of iron with [[menstruation]] and [[pregnancy]]. |
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Revision as of 01:50, 21 March 2004
Haemochromatosis, also spelled hemochromatosis, is a hereditary disease characterized by improper processing by the body of iron from foodstuffs.
It results in the progressive accumulation of iron in the body. By midlife sufficient iron may have been absorbed to damage the liver, pancreas and testes to cause failure of these organs. Cirrhosis, liver cancer, diabetes and impotence may result. A form of arthritis develops in many patients. There is also susceptibility to serious infectious diseases; one such infection may occur after eating raw oysters. Females are relatively protected against these abnormalities, at least until after menopause, because of the loss of iron with menstruation and pregnancy.
People with the abnormal genes do not reduce their absorption of iron in response to increased iron levels in the body. Thus the iron stores of the body increase. As they increase the iron which is initially stored as ferritin starts to get stored as a breakdown product of ferritin called haemosiderin and this is toxic to tissue.
It is one the commonest inheritable genetic defects especially in people of northern European extraction, with about 1 in 10 people carrying the defective gene. There are two main genotypes: C282Y and H63D. C282Y is more serious and the greatest risk of haemochromatosis is for people with two copies of the abnormal gene. People with single copies are essentially normal. People with a copy of the C282Y gene and the H63D gene have a slight risk of haemochromatosis but are usually clinically normal.
The disorder remains asymptomatic until the development of organ failure, but the disease can readily be detected by laboratory studies to measure levels of iron in the blood. Early diagnosis is important because the late effects of iron accumulation can be wholly prevented by periodic phlebotomies (blood donations). Probably a one-time study of iron levels early in adult life would be sufficient to evaluate an individual.
The prevalence of haemochromatosis varies in different populations. In Northern Europeans it is of the order of one in 400 persons. Other populations probably have a lower prevalence of this disease. There exist other causes of excess iron accumulation as well. These include multiple blood transfusions, the presence of certain blood diseases, and the drinking of iron-rich beer by Bantus.
Even if an individual has both copies of the abnormal gene the risk of actual clinical haemochromatosis is still quite low (? about 20%). This is called incomplete penetrance.
These figures are not exact because there is not a strict definition of heamochromatosis. The severity of the disease can vary greatly from person to person and also during a person's lifetime.
see also cirrhosis