Haemochromatosis in the brain. Light micrograph of a section through tissue from the choroid plexus of the brain showing haemochromatosis. This is a condition in which the body absorbs excessive amounts of iron, which builds up in organs and eventually damages them. The condition is caused by a genetic defect. Organ damage can be prevented if the condition is diagnosed early in life. Excess iron is removed by bloodletting, as the blood is the body's largest store of iron.