الفهرس 
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Abstract
Thalassemia is a hereditary anemia resulting from defects in hemoglobin production.
β-Thalassemia, which is caused by a decrease in the production of β-globin chains, affects multiple organs and is associated with considerable morbidity and mortality.
Accordingly, lifelong care is required, and financial expenditures for proper treatment are substantial. Thalassemia is among the most common genetic disorders worldwide; 4.83 percent of the world’s population carry globin variants, including 1.67 percent of the population who are heterozygous for α-thalassemia and β- thalassemia . In addition, 1.92 percent carries sickle hemoglobin, 0.95 percent carry hemoglobin E, and 0.29 percent carry hemoglobin C. Thus, the worldwide birth rate of people who are homozygous or compound heterozygous for symptomatic globin disorders, including α-thalassemia and β- thalassemia , is not less than 2.4 per 1000 births, of which 1.96 have sickle cell disease and 0.44 have thalassemias.
β-Thalassemia is caused by any of more than 200 point mutations and, rarely, by deletions
Individuals with β- thalassemia major have severe anemia and hepatosplenomegaly; they usually come to medical attention within the first two years of life. Without treatment, affected children have severe failure to thrive and shortened life expectancy. Treatment with a regular transfusion program and chelation therapy, aimed at reducing transfusion iron overload, allows for normal growth and development and extends life expectancy into the third to fifth decade. Individuals with β Thalassemia Intermedia present later and have milder anemia that only rarely requires transfusion. These individuals are at risk for iron overload secondary to increased intestinal absorption of iron as a result of ineffective erythropoiesis.
The diagnosis of β-thalassemia relies on measuring red blood cell indices that reveal microcytic hypochromic anemia, nucleated red blood cells on peripheral blood smear, hemoglobin analysis that reveals decreased amounts of HbA and increased amounts of hemoglobin F (HbF) after age 12 months, and the clinical severity of anemia.
Treatment of β-Thalassemia major depends on Regular transfusions that correct the anemia, suppress erythropoiesis, and inhibit increased gastrointestinal absorption of iron. The only available definitive cure is bone marrow transplantation from an HLA-identical sib or cord blood transplantation from a related donor while Treatment of β-Thalassemia intermedia is symptomatic therapy based on splenectomy in most patients, sporadic red cell transfusions in some, and folic acid supplementation.
Hydroxyurea (HU) promotes fetal hemoglobin (HbF) production via a reactivation of γ_-genes as a result of molecular mechanisms that are not yet elucidated. The clinical benefit induced by this compound in patients affected with β-Thalassemia major disease has been repeatedly demonstrated. A significant benefit could be expected in patients with β-thalassemia, because the imbalance in globin chains could be ameliorated by the newly synthesized γ chains being able to neutralize the excess α-chains, which could partially correct ineffective erythropoiesis.