QS Study

Beta thalassemia is more severe than Alpha Thalassaemia because-

The thalassemias are a group of inherited hematologic disorders caused by defects in the synthesis of one or more of the hemoglobin chains. In beta thalassemia, the heterozygous state (called thalassemia minor) is accompanied by no symptoms or at most by very mild anemia. In β thalassemia major there is no production of β chain leading to excess production of α chain within the developing red blood cells. These excess α chains do not form any tetramer but precipitate rapidly. The homozygous form of beta thalassemia (thalassemia major) is not immediately lethal because there is some production of Hb F, which does not contain beta chains.

Fig: thalassaemia – heterogenous group of disorder

But in α – Thalassaemia there is no production of α chain leading to the production of excess γ chain (In new horn) and excess β chain ( In adult) which form γ tetramer (Hb harts) and tetramer (Hb H). Alpha thalassemia, the heterozygous state with a single gene for alpha thalassemia, causes no symptoms or merely mild anemia because there is another gene still able to make alpha chains. These Hb Barts and Hb H are more soluble and less toxic than those derived from a chain in β thalassemia. So the haemolytic anaemia and ineffective erythropoiesis are less severe than β thalassemia. But the homozygous state with both genes for alpha thalassemia is lethal before birth because no alpha chains can be made and without alpha chains, there can be no Hb F or Hb A and without them, there can be no life.