Q.Which of the following is most appropriate for thalassemia?

Thalassemia

Thalassemia is an inherited blood disorder in which the body cannot make enough normal haemoglobin, the oxygen-carrying pigment of red blood cells. Understanding it starts with a look at what haemoglobin is built from.

The structure of haemoglobin — the clue to the disease

Adult haemoglobin is made of four globin protein chains — normally two alpha (α) chains and two beta (β) chains — each holding a haem group that binds oxygen. The genes for the alpha and beta chains must work correctly and in balance for haemoglobin to form properly.

What goes wrong in thalassemia

Thalassemia is caused by a mutation (defect) in the genes that direct the synthesis of these globin chains, so one type of chain is produced in reduced amounts (or not at all). This is the crucial point — it is a quantitative problem, a shortage of a normal chain, rather than a wrong chain. Depending on which chain is affected:

• Alpha-thalassemia — reduced synthesis of the alpha-globin chains.
• Beta-thalassemia — reduced synthesis of the beta-globin chains.

Because the chains are unbalanced, red blood cells form poorly, are fragile and are destroyed easily, leading to anaemia (low haemoglobin), fatigue, and in severe cases the need for repeated blood transfusions.

How it is inherited …