Thalassemia, << `thal` us SEE mee uh, >> is an inherited blood disease that causes anemia. It chiefly affects children whose ancestors came from near the Mediterranean Sea. Thalassemia also afflicts African Americans and some Asian and Middle Eastern peoples. Children with thalassemia do not produce enough hemoglobin, a pigment that gives red blood cells their color and carries oxygen. A shortage of the substance deprives the body’s tissues of oxygen. Symptoms of thalassemia are present at birth or appear about six months later. They include pale skin, irritability, poor appetite, and slow growth. If untreated, thalassemia may cause an enlarged heart, liver, or spleen. The untreated disease also deforms and weakens certain bones, especially in the face.
Thalassemia is caused by abnormalities in the genes that control production of hemoglobin. When these abnormalities affect the parts of hemoglobin called the beta chains, the disease is called beta thalassemia. The severest beta type is called beta thalassemia major, also known as Cooley’s anemia. It occurs in children who inherit defective beta hemoglobin genes from both parents. Without treatment, children with beta thalassemia major may die in infancy. Some children who inherit defective beta genes from both parents develop a milder disease called beta thalassemia intermedia. People who inherit a defective gene from one parent have beta thalassemia minor, also called beta thalassemia trait. These people are rarely ill but can pass the faulty gene on to their children. However, if this trait is inherited with the sickle cell trait, a disease known as sickle beta thalassemia results. This disease has symptoms that closely resemble those of sickle cell anemia (see Sickle cell anemia ).
In some cases, thalassemia can be cured with a bone marrow transplant. This procedure destroys a patient’s blood-forming tissue and replaces it with donor tissue that produces normal amounts of hemoglobin. Many patients receive repeated blood transfusions, which keep hemoglobin near normal levels. Because hemoglobin contains iron, transfusions also supply excess iron that can damage the heart or other organs. Iron chelation therapy removes this excess iron. Patients who tolerate chelation therapy well can live for many years. Another promising treatment uses drugs to stimulate fetal hemoglobin, a form active in unborn babies that becomes much less active after birth.
