| Περίληψη: | The extremely precise function of hemoglobin depends on two main conditions: (a) the invariabe structure of the globin chains (α and β in the normal adult), and (b) the adequate and balanced of the chains, in a way which ensures no excess of the one or the other type of chains within each red cell. Not meeting these prerequisites results in a number of abnormal conditions, most of which are causing serious clinical problems. As a rule, hemoglobin disorders are hereditary and comprise two main groups : (a) the thalassemias, and (b) the hemoglobin variants. The former are characterized by a decrease or complete absence of one or the other type of globin chains which form the Hb molecule. The latter are due to substitutions or deletions of the aminoacids which form the the Hb molecule. All these conditions are transmitted from parents to progeny in heterozygous or homozygous form. These inherited hemoglobin disorders are more common in the Mediterranean basin, and the Middle East, Indian, South China and neighbouring countries; the main reason for this high frequencies is the long lasting genetic pressure of malaria. The Hb disorders constitute a major problem in Greece and include thalassemia major (survival depending on frequent transfusions) and sickle cell anemia (severe vascular obstructions causing pain and other complications), which are presented in this chapter.
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