An Isoelectricfocusing Method to Detect Hewoglobin Variants in Newborn Blood Samples Including the β-Thalassemias

Abstract

An isoelectricfocusing method has been developed to enable large scale screening of newborn blood for hemoglobinopathies. The method utilizes a thin layer agarose gel containing carrier ampholytes in the pH range 6–8. The gradient is non linear allowing increased resolution in the pH region 6.8–7.8 where most hemoglobin variants are isoelectric. The increased resolution between Hb A and Hb F_ac enables screening for β-thalassemia by densitometric analysis. By calculating the ratio of Hb A/Hb F_ac or Hb F/Hb A it is possible to detect newborns heterozygous for β⁺- or βd`-thalassemia. Structural variants, unresolved by other electrophoretic methods, are easily detected. Seventy-two samples can be analyzed on a single gel in 90 minutes. Traces of hemoglobin variants can be detected by a heme-specific stain requiring no destain step.