Thalassaemia (Mediterranean anemia; Cooley's anemia)

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What is Thalassaemia?

Thalassaemia arises when there is an imbalance in the production of alpha and beta globin chains. Normal haemaglobin contains two chains (globin chains - alpha and beta), which are folded in such a way so as to hold haem molecules within the fold and letting the haem combine reversibly with oxygen.

In normal haemoglobin (Hb) there is 1:1 balance in in the production of alpha and beta globin chains. This production leads to the collection (precipitation) of globin chains within red cells or precursors of red cells. This results in cell damage, death of red cell precursors in the bone marrow and red cell destruction in the blood (haemolysis).

There are two beta chains and two alpha chains and deletion of one of these genes results in an imbalance in their production and various clinical presentations

Who gets Thalassaemia?

Worldwide, 15 million patients have clinically apparent thalassemic disorders. Reportedly, thalassaemia carriers in India alone number approximately 30 million. These facts confirm that the thalassemias are among the most common genetic disorders in humans. They are encountefound among all ethnic groups and in almost every country around the world.

Certain types of thalassaemia are more common in specific parts of the world. Beta thalassaemia is much more common in Mediterranean countries such as Greece, Italy, and Spain. Many Mediterranean islands, including Cyprus, Sardinia, and Malta, have a significantly high incidence of severe beta thalassemia, which is a major public health problem. Beta thalassaemia is also common in North Africa, the Middle East, India, and Eastern Europe. Conversely, alpha thalassaemia is more common in Southeast Asia, India, the Middle East, and Africa.

Predisposing Factors

Family history is the only predisposing factor to this group of similiar diseases.

Progression

Natural history depends on the type of thalassaemia (alpha or beta) and its severity.

Beta thalassaemia:

Beta thalassaemia trait - asymptomatic with mild or absent anaemia.

Beta thalassaemia intermedia - moderate anaemia, does not require regular transfusions. Patients may have splenomegaly and bone deformities, recurrent leg ulcers, gallstones and infections.

Beta thalassaemia major - progression from failure to thrive and recurrent bacterial infections in infancy to severe anaemia at 3-6 months of age. Blood transfusions are required to keep Hb above 10g/dL

Alpha thalassemia:

Haemoglobin Barts - incompatible with life

Haemoglobin H - Most patients are not dependent on transfusions.

Alpha Thalassaemia trait - mild anaemia - normal life expectancy

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