New techniques for the prenatal diagnosis of hemoglobinopathies.

Two new techniques have been devised for the prenatal diagnosis of hemoglobinopathies performed on fetal blood samples. Isoelectric focusing (IEF) of hemoglobins was compared to the classical chromatography of labelled globin chains for 51 fetal blood samples, 40 being obtained for prenatal diagnosis of hemoglobinopathies, in Paris. In all cases the two methods provided identical results. Adult hemoglobin was quantitatively evaluated. In addition blood samples obtained in other centers after abortion of 22 fetuses homozygous for beta thalassemia did not exhibited measureable amounts of Hb A by IEF. The fetal blood must be free of maternal contamination. If present maternal red blood cells can be completely eliminated by selective lysis using the 0RSKOV reaction. A chromatography of hemoglobins on Biorex 70 has been devised very recently to overcome the two limitations of IEF: First the contamination of fetal blood samples by maternal cells, and second the impossibility to evaluate Hb A when present in proportion below 1%. The chromatography of hemoglobins on Biorex 70 is performed in 75 minutes with 0.1 mg of hemoglobin present in membrane free hemolysate. The optical density recording allows to evaluate .5% of Hb A and to detect .1% of Hb A. In addition, the radioactivity profile of the chromatography can be determined. It has to be used in case of maternal contamination.