A 28-year-old African-American woman develops acute intravascular hemolysis with hemoglobinuria 2 days after starting primaquine for malaria prophylaxis. The peripheral smear shows 'bite cells' and Heinz bodies on crystal violet stain. The enzyme deficient in this condition is located in which metabolic pathway?

• A Hexose monophosphate (pentose phosphate) shunt ✓
• B Glycolysis (Embden-Meyerhof pathway)
• C Methemoglobin reductase system
• D Glutathione synthetase pathway

Explanation

G6PD deficiency impairs the hexose monophosphate shunt, reducing NADPH generation and therefore glutathione reduction. Without reduced glutathione, oxidative stress from drugs like primaquine or dapsone causes hemoglobin denaturation (Heinz bodies) and membrane damage (bite cells from splenic removal of Heinz body-containing portions). G6PD is X-linked and affects males predominantly.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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