Enzyme deficiency diseases glucose-6-phosphate dehydrogenase

In addition to a glucose-6-phosphate dehydrogenase deficiency resulting from enzyme deletion, forms of the disease have been described in which glucose-6-phosphate dehydrogenase is qualitatively abnormal ... 

In many cases there is no good correlation between the levels of deficiency in glucose-6-phosphate dehydrogenase and the severity of the hemolytic anemia. Thus while some individuals with variants with levels of activity lower than 5% of normal present no symptoms, others with variants with more than 20% of normal activity have hemolytic disease. Yoshida has studied the properties of some of the variants associated with hemolytic disease and demonstrated that at least in some cases the variant enzyme is strongly inhibited by NADPH and ATP. As a result the ratio of NADPH to NADP in the red cells is reduced and the concentrations of reduced glutathione are inadequate [203]. 

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