Patients have severe beta-thalassemia or one of the thalassemia variants. Thalassemia is a hereditary disease in which the bone marrow produces abnormal red blood cells that have a shorter life span than normal red blood cells. Because of that, the patient has chronically low red blood cell numbers (anemia) and need regular blood transfusions to help the patient feel better and to help prevent damage to important organs such as the heart. The following treatments are currently available to patients: lifelong blood transfusions and drugs that help remove iron from the body, and long-term antibiotics to prevent infections. These treatments are difficult for patients to take, and do not stop the effects of the disease.