Haemochromatosis.

Primary, hereditary or genetic haemochromatosis is one of the most common inherited disorders in a Caucasian populations with a disease frequency of 1:300-400 and a carrier frequency of approximately 10%. The basic genetic defect remains unknown, although the haemochromatosis gene has now been cloned and is known to be a member of the MHC non-classical class I family. Many factors--environmental, genetic and non-genetic in nature--influence the degree of iron loading in affected individuals. In particular, pathological and physiological blood loss influence iron stores in haemochromatosis. The iron concentration in the liver is an important determinant of survival because a hepatic iron concentration in excess of 400 mumol/g dry weight is usually associated with cirrhosis. Patients with cirrhosis secondary to haemochromatosis are at risk of hepatocellular carcinoma. The combination of improved awareness of the disease and the appropriate use of genetic testing for the common C282Y mutation should lead to earlier diagnosis and therapy.