Clinical - Hematologic, Pediatrics
Thalassemia is a disorder of production of one of the proteins of hemoglobin. Hemoglobin is a protein in red blood cells and is responsible for the transport of oxygen to tissues. Hemoglobin is made up of two proteins, alpha globin and beta globin.
Normal hemoglobin has two alpha and two beta globin protein chains. A deficiency or absence of the alpha chain results in Alpha-thalassemia and a deficiency or absence of one or more of the beta chains results in Beta-thalassemia. Beta-thalassemia occurs in 1 in 25,000 births in north america.
The beta chain requires a gene from each parent to produce the correct quality and quantity of beta globin. If the gene from one parent is missing or incomplete, the child will develop Beta-thalassemia minor. If the gene from both parents is missing, the child will develop Beta-thalassemia major or Cooley’s anemia.
Thalassemia minor results in a microcytic red cell but otherwise there are no other sequelae. Thalassemia major results hemolysis. Newborns with Beta-thalassemia major usually are normal at birth because of the initial predominance of hemoglobin F. As this hemoglobin is replaced with defective hemoglobin, they develop anemia from hemolysis during the first year of life. The clinical findings result from the sequelae of severe anemia. On physical exam patients may be pale and jaundice from the hemolysis. Patients may also present with growth retardation, skeletal abnormalities, and hepatosplenomegaly. With regular blood transfusions, life expectancy is good. Without transfusions, life expectancy is limited to a few years. A bone marrow transplant may be curative but this treatment option is limited to patients with exact matching from a sibling or other family member.
Screening for Beta-thalassemia with hemoglobin electrophoresis occurs in the newborn period.
Giardina PJ, Forget BG. Thalassemia syndromes. In: Hoffman R, Benz EJ, Shattil SS, et al., eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 41.
DeBaun MR, Frei-Jones M, Vichinsky E. Hemoglobinopathies. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 456.