Thalassemia is a hereditary disease in which the bone marrow produces red blood cells that have a shorter life span than normal red blood cells. Patients with this disease accumulate iron in their bodies because they require frequent blood transfusions throughout their lives. The transfused red blood cells eventually break apart and release their contents (including iron) into the bloodstream. The liver removes excess iron from the bloodstream and stores it in liver tissue. Excessive accumulation of iron damages the liver and causes scar tissue to form. Accumulation of scar tissue causes a condition known as cirrhosis. Other diseases also cause cirrhosis, particularly hepatitis C virus (HCV) infection and severe alcoholism. For many years, doctors have believed that cirrhosis is permanent, perhaps because the conditions that cause it are usually permanent. Recently, doctors have been able to cure thalassemia by transplanting bone marrow from a normal donor. Since cured patients no longer need transfusions, much less iron enters their bodies, and iron may leave the liver and reduce the stimulus to form scar tissue. Many patients with thalassemia already have cirrhosis before they undergo bone marrow transplantation; therefore, it is possible to see whether cirrhosis decreases after successful treatment of thalassemia.