The Interference of Leukocytes and Platelets With Measurement of Glucose-6-Phosphate Dehydrogenase Activity of Erythrocytes With Low Activity Variants of the Enzyme

T HE MEDITERRANEAN variety of glucose-6phosphate dehydrogenase (G6PD) deficiency is characterized by severely decreased catalytic activity in the affected erythrocytes and is therefore classified as belonging to class II in the usual tabulations of G6PD variants.’ However, evidence has been provided that in Mediterranean countries there are several polymorphic G6PD variants sharing activity levels below I 0% of those found in normal subjects.2 We have now investigated in greater detail the actual levels of G6PD in erythrocytes from G6PDdeficient hemizygous Sardinian subjects. We show here that after complete removal of leukocytes and platelets, the G6PD activity of pure erythrocytes from these subjects is far lower than reported previously. Accordingly, most of the biochemical properties of the mutant enzyme protein that were formerly ascribed to erythrocyte G6PD should be regarded as those of the enzyme from contaminating leukocytes and/or platelets.