Storically, Beta Thalassemia has been classified into
- Beta thalassemia, patients are clinically asymptomatic
- Beta thalassemia intermedia, with clinically heterogeneous and genotypic disorders, ranging in severity from mild to severe transfusion-dependent status.
- Beta thalassemia major with severe, transfusion-dependent anemia.
Beta-thalassemia occurs, in which the beta chains of hemoglobin are not produced and there is an accumulation of alpha chains, with formation of tetramers that can precipitate, releasing heme and causing oxidative damage. As a result, red blood cells are weaker and more fragile, living much less, causing hypoxia. Hypoxia causes splenic and hepato-megaly and an alteration of the bone marrow, which increases in size to produce more red blood cells. Increased erythropoiesis causes decreased expression of hepcidin, which in turn results in increased levels of ferroportin and iron availability. Therapy is a periodic administration of transfusions and iron chelators, such as EDTA, which arranges an octahedron, heme-like, around iron.
Currently EDTA (too non-specific) is replaced by deferoxamine, a peptide used as a siderophore in bacteria, while in humans it binds iron and, at this point, is eliminated in the urine.
