Defective spectrin dimer self-association in thalassemic red cells

The relative proportions of spectrin tetramer and dimer forms extrated from red cell membranes in a low ionic strength buffer at 4 degrees C were determined for 15 normal subjects, 27 subjects with alpha-thalassemia (7 alpha-thalassemia trait, 9 Hb H disease (alpha-thal 1/alpha-thal 2) and 11 Hb H with Hb Constant Spring (CS), 23 subjects with beta-thalassemia (6 beta-thalassemia trait, 5 homozygous beta-thalassemia, 11 beta(0)-thalassemia with Hb E and 1 beta(+)-thalassemia with Hb E), 6 subjects with Hb E (2 homozygous and 4 carriers) and 1 subject with combined alpha-thal 1/Hb CS and Hb E (AE Bart's disease). In all subjects (except carriers of Hb E and 1 splenectomized case of beta(0)-thal/Hb E) spectrin dimer forms were elevated when compared to levels in normal controls, but there were no significant differences between carrier and disease forms. Conversion of spectrin dimers to tetramers at 30 degrees C was reduced in the thalassemic subjects with disease but was within normal range for thalassemic carriers.