The Thalassemias are a group of inherited blood disorders caused by abnormal production of hemoglobin.  They are more common in people from South East Asia, India, the Middle East, Mediterranean countries, and Africa.

  Hemoglobin, the oxygen transporting molecule, has a complex structure.  In the middle is an iron molecule, surrounded by a chemical ring (Heme) that is surrounded in-turn by two protein chains (the globins).

Normally, adult hemoglobin is mainly of the A variety.  Hemoglobin A has one a2 globin chain and one ß2 globin chain.  Normally, adults also have small amounts of Hemoglobin A2 (one a2 chain and one d2 chain), and Hemoglobin F (one a2 and one ?2).

Thalassemia occurs when a genetic defect causes reduced production of a globin chain type.

Alpha Thalassemia is due to reduced or absent alpha (a) chain production and Beta Thalassemia is due to reduced or absent beta (ß) chain production.

In general, there are two types of each Thalassemia: the heterozygote (Thalassemia trait) in which you have one gene for the condition, and the homozygous form (the full disease) in which you have two genes for the condition.

Persons with alpha or beta Thalassemia trait are usually asymptomatic, while homozygotes are significantly affected. It is important for persons with Thalassemia trait to undergo genetic counseling and studies to determine the risk to their offspring.