What Is Beta Thalassemia?

Blood Transfusion
Blood Transfusion. Rafe Swan/Cultura/Getty Images

Beta thalassemia is an inherited anemia where the body is unable to produce hemoglobin normally. Hemoglobin A (the major hemoglobin in adults) contains two alpha globin chains and two beta globin chains. In beta thalassemia, the bone marrow is unable to produce a normal amount of beta globin resulting in little to no hemoglobin A. Also, there is an excess of alpha globin not bound to beta globin that causes red cell breakdown known as hemolysis.

Who Is at Risk?

Beta thalassemia is an inherited condition. It requires both parents to be carriers of the disorder called beta thalassemia trait or minor. When both parents have beta thalassemia trait, they have a 1 in 4 chance of having a child with beta thalassemia disease. Unfortunately, because beta thalassemia trait causes no symptoms, parents may be unaware of this risk prior to pregnancy.

What Are the Types of Beta Thalassemia?

Beta thalassemia can be classified in two ways: by the genetic mutation inherited or by transfusion need.

Genetic mutations

Beta zero thalassemia: The zero in beta zero mutation indicates that no beta globin can be produced by that chromosome.

Beta plus thalassemia: Beta globin is produced by in reduced amounts. The amount beta globin produced varies greatly with the particular mutation inherited. Some mutations produce almost no beta globin making them clinically similar to beta zero.

Transfusion need

Beta thalassemia major: Beta thalassemia major is defined by the need for life-long transfusions, usually monthly (termed hypertransfusion therapy).

Beta thalassemia intermedia: Usually moderate anemia that may require occasional transfusions (during illnesses, puberty, etc) but not on a regular basis.

Beta thalassemia trait/minor: This results in a mild asymptomatic anemia usually picked up on routine complete blood count.

How Is Beta Thalassemia Diagnosed?

In general, beta thalassemia major is identified on the newborn screen. In these infants, the test will only identify hemoglobin F (or fetal), no hemoglobin A. These children are referred to hematologist to be monitored closely. Some more severely affected beta thalassemia intermedia patients will also be identified this way.

Some more mildly affected patients will be identified on routine complete blood count (CBC). The CBC will reveal a mild to moderate anemia with very small red blood cells. This can be confused with iron deficiency anemia. Diagnosis is confirmed by a hemoglobin profile (also called electrophoresis). In beta thalassemia intermedia and trait this testing reveals elevation in hemoglobin A2 (a 2nd form of adult hemoglobin) and sometimes F (fetal).

What Are the Treatments for Beta Thalassemia?  

Beta thalassemia trait requires no treatment.

 People with beta thalassemia trait will have lifelong mild anemia.

Transfusion: Patients with beta thalassemia major require lifelong transfusions. Transfusion therapy is used to suppress red blood cell production in the bone marrow. Beta thalassemia intermedia patients may require transfusion therapy during illnesses and puberty (during growth spurt).

Iron chelation therapy: Patients with beta thalassemia major receive excess iron through red blood cell transfusions. This excess iron can cause damage to organs, particularly the heart. Iron chelation assists the body in removing iron. These can be given as an oral medication or an infusion under the skin.  Patients with beta thalassemia intermedia may develop iron overload even in the absence of blood transfusions secondary to increased absorption of iron in the small intestine.

Splenectomy: The spleen can become massively enlarged due to red cell breakdown (hemolysis) as well as red blood cell production in the spleen. If transfusion need increases or other blood cell counts go down due to trapping in the spleen, the spleen may need to be removed surgically.

Hydroxyurea: Hydroxyurea has been used to increase fetal hemoglobin production. Success has been variable.

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