(1) Thalassemia is an autosomal-eeessive disorder. The synthesis of alpha ciiains are controlled by two genes, (HBA1 and HBA2) on chromosome 16. Beta chain synthesis is controlled by gene HBB located on chromosome 11. Two alpha chains and two beta chains together form four polypeptide chains that make heterotetrameric haemoglobin molecule. But when there is defective gene on either of chromosome 16 or 11, there is quantitative abnormality of polypeptide globin chain synthesis. This results into thalassemia.
(2) Depending upon which chain is affected, thalassemia is classified as, alpha (α) thalassemia and beta (β) thalassemia.
(3) The clinical symptoms of thalassemia are as follows:
- Pale yellow skin.
- Anaemia due to inability to synthesize haemoglobin.
- Slow growth and development.
- Variation in the shape and size of RBCs.
(4) Patients need regular blood transfusions to cope with the disorder.
