Thalassemia
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Classification and external resources
MedlinePlus 000587
eMedicine ped/2229 radio/686
Thalassemia (from Greek θαλασσα, thalassa, sea + αίμα, haima, blood; British spelling, "thalassaemia") is an inherited autosomal recessive blood disease. In thalassemia, the genetic defect results in reduced rate of synthesis of one of the globin chains that make up hemoglobin. Reduced synthesis of one of the globin chains can cause the formation of abnormal hemoglobin molecules, and this in turn causes the anemia which is the characteristic presenting symptom of the thalassemias.
Thalassemia is a quantitative problem of too few globins synthesized, whereas sickle-cell anemia (a hemoglobinopathy) is a qualitative problem of synthesis of an incorrectly functioning globin. Thalassemias usually result in underproduction of normal globin proteins, often through mutations in regulatory genes. Hemoglobinopathies imply structural abnormalities in the globin proteins themselves [1]. The two conditions may overlap, however, since some conditions which cause abnormalities in globin proteins (hemoglobinopathy) also affect their production (thalassemia). Thus, some thalassemias are hemoglobinopathies, but most are not. Either or both of these conditions may cause anemia.
The disease is particularly prevalent among Mediterranean peoples, and this geographical association was responsible for its naming: Thalassa (θάλασσα) is Greek for the sea, Haema (αίμα) is Greek for blood. In Europe, the highest concentrations of the disease are found in Greece, including the Greek islands; in parts of Italy, in particular, the lower Po valley; in southern Italy; and in the Italian islands. Sicily, Sardinia (Italian islands), Corsica (French island) and Cyprus and Crete (Greek islands) are heavily affected in particular; the higher incidence in these islands likely is because of the higher inbreeding that occurs in isolated populations. But Asia now has even greater prevalence, with the highest concentration of carriers (18% of the population) in the Maldives.
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