A: The rate of disappearance of glutathion(GSH) from the blood of a G6PD-deficient male, a normal subject, and an artificial mixture. One-cc samples of whole blood were incubated with 5 mg acetylphenylhydrazine. Each point represents the average of duplicate determinations. B: The rate of disappearance of GSH from the blood of three females with “intermediate” blood G6PD levels. C: The rate of methemoglobin reduction in the red cells of a G6PD-deficient male, a normal subject, and an artificial mixture. The reaction mixture, incubated at 37°C, contained the following: glucose 5 mg/cc; Nile blue sulfate 11 μg/mL; red blood cells 29% suspension; all in isotonic potassium phosphate buffer at pH7.4.D: The rate of methemoglobin reduction in the red cell of a Negro female with “intermediate” red cell G6PD activity.(From: Beutler E, Proc Natl Acad Sci U S A 1962;48:9, with permission from the National Academy of Sciences.⁵⁰)