Glycerol-3-Phosphate Dehydrogenase Activity in the Red Cells of Patients With Thalassemia

L-α-Glycerol-3-phosphate dehydrogenase (EC 1.1.1.8) has been reported to be absent in the erythrocytes of normal adults, but can be found in those of cord blood and of thalassemia major. The aim of this study was to investigate whether there is any relation between GDH and γ-chain synthesis. Erythrocyte GDH activity was determined on 118 different blood samples. It was undetectable in normal adult erythrocytes and definitely high in cord blood cells (23.6 IU/1011 RBC). Considerable GDH activity was also noted in patients with thalassemia major (11.0 IU/1011 RBC) as well as in cases with pronounced reticulocytosis (11.4 IU/1011 RBC). Red cells from β-thalassemia heterozygotes exhibited moderate but distinct GDH activity (5.2 IU/1011 RBC). After fractionation into young and old erythrocyte populations, clearly higher GDH activity was found in the younger cells; however, there was no significant correlation with the reticulocyte count. Presence of reticulocytes alone appears insufficient to explain the values obtained in cord blood and the thalassemias, especially heterozygous. Furthermore, no direct correlation between GDH and fetal hemoglobin (HbF) was obtained in cord and thalassemic erythrocytes.