Prenatal diagnosis of thalassemia and hemoglobinopathies in Switzerland.

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 beta-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 alpha-thal 1 with beta-thalassemia resulted in an unusually high Hb level because of balanced alpha and beta 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.