Causes and types of Thalassaemias

Causes and types of Thalassaemias 
  • thalassaemias are inherited disorders of defective synthesis of globin chains in haemoglobin they cause haemolysis anaemia and ineffective erythropoiesis they are found mainly in Africa the Orient Mediterranean ,Asia and the middle East
  • There are three types of thalassaemias 1- beta -thalassaemia major(homozygous)2- beta- thalassaemia minor (heterozygous) 3- alpha- thalassaemia 
  • beta thalassaemia the most common of the thalassaemias beta thalassaemia minor is the heterozygous state it produces a symptmless microcytosis which may be accompanied by a mild anaemia 
  • beta thalassaemia major is the homozygous form with either none or a much reduced number of beta chains it presents as a severe anaemia from 3 month onwards needing regular transfusion , clinically there is a failure to thrive with recurrent infections extra medullary haemopoiesis causes hepatosplenomegaly and bone expansion leading to frontal bossing and a characteristic appearance 
  • the aim should be to transfer to an Hb above 10 g\dl while preventing iron overload with desferrioxamine an iron -chelating agent . folate supplements are required splenectomy for hypersplenism and bone marrow transplantation can be considered 
  • alpha - thalassaemia four genes are responsible for the alpha chains and the disease is caused by gene deletions , if all four genes are deleted the conditions is fatal . a three - gene deletion causes moderate anaemia and splenomegaly HbH  disese patients are not usually transfusion dependent . two gene deletion causes a microcytosis which may be associated with a mild anaemia this is alpha - thalassaemia trait

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