A 25-year-old woman develops episodic hemolytic anemia triggered by fava beans and infections. G6PD deficiency is suspected. The enzyme is most critical in which pathway that protects erythrocytes from oxidative damage?

• A Embden-Meyerhof glycolytic pathway
• B Rapoport-Luebering shunt
• C Methemoglobin reductase pathway
• D Hexose monophosphate (HMP) shunt ✓

Explanation

G6PD is the rate-limiting enzyme of the HMP shunt (pentose phosphate pathway), generating NADPH that maintains glutathione in its reduced form, which neutralizes H2O2 and protects erythrocyte membranes and hemoglobin from oxidative denaturation. In G6PD deficiency, exposure to oxidants causes Heinz body formation and intravascular hemolysis. The Embden-Meyerhof pathway generates ATP; the Rapoport-Luebering shunt produces 2,3-BPG.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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