Thalassemia is one of the most prevalent causes of chronic hemolysis worldwide and the commonest cause of chronic hemolysis in Egypt. It results from hemoglobinopathies, consisted of 2 main types (thalassemia major and thalassemia minor) and each type has many different subtypes.Beta-thalassemia major ( β -thalassemia) presents after 6 months of age with symptoms of chronic hemolysis as facial bone deformities, fatigue, growth failure, dyspnea, jaundice and hepatosplenomegaly. Glucose 6 phosphate dehydrogenase (G6PD) is the enzyme responsible for catalyzing the first step in the pentose phosphate pathway (the hexose monophosphate shunt) to generate Nicotineamide Adenine Dinucleotide Phosphate (NADPH) which is subsequently utilized in processes that reduce hydrogen peroxide (H2O2) to water, ameliorating oxidative stress in red blood cells (RBCs). Approximately 400 million people worldwide are G6PD deficient making it the most common human enzyme deficiency.Nowadays, blood donors are not routinely screened for G6PD deficiency, and blood centre policies differ regarding deferral of known G6PD-deficient donors, so RBC transfusion-dependent patients may be at greater risk of receiving blood from G6PDdeficient donors.Because G6PD activity decreases as RBCs age in vivo the question was raised as to whether the same phenomenon occurs during refrigerated storage. Studies of G6PD activity during RBC storage under standard blood-banking conditions show a range of results, with some demonstrating no decrease in G6PD activity or activity decreases of up to 35% , may be attriubated to difference in storage methods

Glucose-6-phosphate dehydrogenase deficiency, B Thalassemia