Thalassemias

[Luis Fok]

Thalassemias are a group of inherited disorders resulting from an imbalance in the production of one of the four chains of amino acids that make up hemoglobin (the oxygen-carrying protein found in red blood cells).

Symptoms depend on the type of thalassemia.
Some people have jaundice and abdominal fullness or discomfort.
Diagnosis usually requires special hemoglobin tests.
Mild thalassemia may not require treatment, but severe thalassemia may require bone marrow transplantation.

(See also Overview of Anemia.)
Hemoglobin is made up of two pairs of globin chains. Normally, adults have one pair of alpha chains and one pair of beta chains. Sometimes one or more of these chains is abnormal. Thalassemias are categorized according to the amino acid chain affected. The two main types are

Alpha-thalassemia (the alpha globin chain is affected)
Beta-thalassemia (the beta globin chain is affected)

Alpha-thalassemia is most common in blacks (25% carry at least one copy of the defective gene), and beta-thalassemia is most common in people of Mediterranean and Southeast Asian ancestry.
Thalassemias can be classified according to how severe they are.

Thalassemia minor: Causes no symptoms or mild
Thalassemia intermedia: between mild and severe symptoms
Thalassemia major:Severe symptoms that require treatment