Globin chain electrophoresis for prenatal diagnosis of beta thalassemia

Determination of the biosynthetic beta/gamma ratio in samples of fetal blood is used for prenatal diagnosis of thalassemia. The current method, carboxymethyl cellulose chromatography (CMC), is cumbersome, slow, and expensive. Radiolabelled globin chains (A gamma, G gamma, beta, and alpha) 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 beta/gamma ratio in 24 samples of blood from fetuses at risk for beta thalassemia. CMC column data were compared with quantitations from fluorograms of slab gels. The beta/gamma 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 beta/gamma ratio is between 0.01 and 0.03 by gel.