pathogenesis
Last reviewed 01/2018
Defective beta-chain production results in excess alpha-chain synthesis, which are unstable and precipitate in the red cell precursors causing their destruction in the bone marrow (1). The resulting anaemia leads to increased erythropoietin production, massive proliferation of the marrow and the establishment of extramedullary haemopoiesis which contributes to the hepatosplenomegaly seen in these patients (2). However, since most of the red cell precursors never reach the peripheral blood, there is gross ineffective erythropoiesis. (2)
There is progressive splenomegaly (2). The massive expansion of the marrow leads to serious bone deformities with typical mongoloid facies, bossing of the skull, and thinning and trabeculation of the long bones and bones of the hands and feet.
Increased Iron absorbtion in the gastrointestinal tract leads to iron overload and deposition in all organs, especially in the liver and heart (2).
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