Diagnosis of pyruvate kinase deficiency in a transfusion-dependent patient with severe hemolytic anemia

In a 2-yr old girl a hemolytic anemia was present since birth requiring multiple blood transfusions. Pyruvate kinase deficiency was suspected on the basis of a marginal enzyme activity, but could not be established due to the presence of massive numbers of donor cells in her peripheral blood. However, by density fractionation we succeeded in the isolation of a small fraction of the patient's own cells, in which a severe pyruvate kinase deficiency could be detected. In contrast hexokinase and glucose-6-phosphate dehydrogenase activities were extremely high, which is indicative that a very immature cell population is present in this fraction. In immunofluorescence studies a clear crossreaction was apparent with anti M2-type pyruvate kinase antibodies, whereas only a faint reaction with anti L-type could be detected. Despite the presence of a slight amount of L-type immunoreactive material, the residual activity in the patient's cell fraction could only be attributed to M2-type pyruvate kinase as was shown by cellulose acetate electrophoresis.