The two α-like chains contain 141 amino acids while the non-α-like chains contain 146 amino acids. Each chain is associated with one haem molecule on the interior of the shell that is essential for oxygen uptake and release. The four subunits are two pairs of identical polypeptide chains: a pair of identical α or α-like chains and a pair of identical non-α or non-α-like chains. A prevention program would be useful to overcome these problems, but it requires a preliminary knowledge of hemoglobin, disease pathophysiology, as well as a spectrum of globin gene mutations among different populations. Treatment of β-thalassemia, albeit more and more available, still represents a significant drain of the country’s resources due to the disease’s major complications. This high prevalence of thalassemia makes it one of the major health problems and a priority genetic disease. However, it is more readily recognized where inherited hemoglobin abnormalities are rare and less likely to cause diagnostic confusion. Īcquired abnormalities of hemoglobin synthesis may also arise as a secondary manifestation of hematologic neoplasia and can be seen in any population. Generally, thalassemias affect all races, particularly people of Mediterranean origin, Arabs, and Asians with variable incidences, where the highest reported rate is in the Maldives (18% carriers’ rate), followed by that of descendants from Latin American and Mediterranean countries while the reported incidence rate is very low in Northern Europe (0.1%) and Africa (0.9%). This selective survival advantage of carriers or heterozygous advantage may be responsible for the perpetuation of the mutation in some populations. Thalassemias confer a degree of protection against malaria, due to the blood cells’ easy degradation. It is now clear that thalassemias occur much more frequently, and in more racial groups, than was previously realized. Thalassemias are a group of inherited microcytic, hemolytic anemias characterized by defective Hb synthesis. Furthermore the study of these disorders shows great promise of answering some fundamental questions about the genetic mechanisms involved in defective protein synthesis. The revelation of the molecular basis of thalassemia lead to the concept of “molecular pathology and molecular medicine”, with a shift of emphasis from illness in patients or their organs to pathological affection at the cellular and molecular level. Interest in the Hb molecule arose from its changes in a series of common clinical intermingled conditions, caused either by its structural variants (hemoglobinopathies), defects of synthesis (thalassemias), or a diverse group of defects in the developmental progression from fetal to adult hemoglobin production (HPFH). During the past few years there has been a rapid increase of knowledge in the field of genetic control of hemoglobin synthesis in health and disease, which led to reviving the interest in thalassemia and associated disorders of hemoglobin (Hb) production.
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