We report a Swiss-Spanish family three members of which have the clinical picture of thalassemia intermedia. Restriction endonuclease mapping of the alpha-globin cluster and digestion with Mae I of the in vitro amplified 5' segment of the beta-globin gene shows a combination of triplicated alpha globin locus, anti-3.7 kb type, with heterozygous codon 39 C----T beta (0) thalassemic mutation. These, as well as 16 similar cases reported in the literature, permit the following conclusion: a single extra alpha-globin gene gives rise to a clinically significant degree of dyserythropoietic anemia only when it interacts with a severe beta(+) or beta(0) thalassemic mutation.
During a 10‐month period, 10 couples originating from Africa (3), the tropics (1) and the thalassemia‐belt region (6), living in Switzerland, requested prenatal diagnosis of hemoglobinopathies. Hb SS (twice), Hb Bart's (Hydrops fetalis) and β‐thalassemia major were diagnosed either by gene mapping or by direct detection of the mutations in DNA amplified by the PCR procedure. Whenever it was possible to obtain fetal blood or tissue, diagnosis was confirmed. In one Vietnamese man, concomitant existence of α‐thal 1 with β‐thalassemia resulted in an unusually high Hb level because of balanced α and β globin synthesis. The 10 couples examined originated from 7 different countries and presented at least 7 different Hb pathologies. This variety of pathologies represents the main difficulty for prenatal diagnosis of hemoglobinopathies in a non‐endemic country. A diagnostic approach to overcome this problem is developed.
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