Globin Chain Electrophoresis for Prenatal Diagnosis of β Thalassemia

Abstract

Determination of the biosynthetic β/γ ratio in samples of fetal blood is used for prenatal diagnosis of thalassemia. The current method, carboxymethyl cellulose chromatography (CMC), is cmbersome, slow, and expensive. Radiolabelled globin chains (A_γ, G_γ, β, and α) can also be separated by electrophoresis in slab gels containing polyacrylamide, acid, urea, and Triton X-100. The radioactive bands are detected by fluorography. We determined the β/γ ratio in 24 samples of blood from fetuses at risk for β thalassemia. CMC column data were compared with quantitations from fluorograms of slab gels. The β/γ synthetic ratios correlated (r=0.91), although the ratios were slightly less by gel than by column. The gel method is simple, inexpensive, and permits up to a dozen simultaneous analyses. Confirmatory CMC columns need only be run if the β/γ ratio is between 0.01 and 0.03 by gel.