You now know more about what causes hemochromatosis. Recall David, the college student you read about in this chapter’s Everybody Has a Story. Can you now explain with some detail why hemochromatosis alters normal iron regulation in the body?

Answer 1

David has a condition called hereditary hemochromatosis that was only discovered in 1996. It is now known that the reason for the increased iron absorption in individuals with hemochromatosis is a defect in the gene (DNA) that codes for one of the transport proteins involved in regulating intestinal iron transport.
Iron is stored intracellularly as ferritin and hemosiderin. Ferritin synthesis is regulated according to iron availability by a system of cytoplasmic binding proteins (IRP-1 and -2) and a noncoding iron regulatory element on mRNA (IRE). When iron is abundant (as in hemochromatosis), sites on the ferritin molecule are blocked from further iron binding, which promotes increased synthesis of ferritin. Ferritin is also the storage form of iron and tends to accumulate in the parenchymal cells in the periportal areas of the liver. With time, and excessive iron absorption, these parenchymal cells of the liver are destroyed and replaced with fibrous tissue, leading to a condition known as hepatic cirrhosis. The destruction of the liver cells from too much iron being deposited releases the liver enzymes, alanine aminotransferase and aspartate aminotransferase. Once the liver enzymes are released, they are detected at high levels in the bloodstream.