Two new glucose‐6 phosphate dehydrogenase (G6PD) variants associated with hemolytic anemia: G6PD amman‐1 and G6PD amman‐2

Abstract

Two glucose‐6‐phosphate dehydrogenase (G6PD) variants were investigated. G6PD Amman‐1 was partially purified from the red cells of a patient suffering from recurrent jaundice and spontaneous episodic attacks of severe hemolysis in the absence of oxidant drugs, infection, or fava beans. The enzymatic characteristics of G6PD Amman‐I were markedly reduced activity, fast eletrophoretic mobility, slightly increased km for NADP, normal km for G‐6‐P, normal heat stability, normal utilization of substrate analogues 2‐deoxy G‐6‐P and deamino‐NADP, and a monophasic pH curve with a peak at 8.5 to 9.3. The second variant, G6PD Amman‐2, was partially purified from the red cells of a patient suffering from recurrent jaundice with episodic mild hemolysis caused by infection or unknown factors. G6PD Amman‐2 characteristics were severely reduced activity, slow electrophoretic mobility, normal km for NADP, decreased km for G‐6‐P, decreased heat stability, increased utilization of substrate analogues, and a monophasic pH curve with a narrow peak at pH 9.5. The red cell level of reduced glutathione was markedly decreased with twofold increase in the activity of glutathione reductase in the patient with G6PD Amman‐2.