A 25-year-old African-American man develops acute hemolytic anemia with Heinz bodies after taking primaquine. The enzymatic defect causes hemolysis because:

• A Spectrin deficiency destabilizes the RBC membrane skeleton
• B Pyruvate kinase deficiency reduces ATP, causing premature RBC death
• C Absent band 3 protein prevents CO2 transport, causing intracellular acidosis
• D Reduced NADPH production impairs regeneration of reduced glutathione, leaving Hb vulnerable to oxidative denaturation ✓

Explanation

G6PD deficiency reduces the HMP shunt, lowering NADPH. NADPH is essential to regenerate reduced glutathione (via glutathione reductase), which detoxifies oxidants. Oxidative stress from primaquine oxidizes Hb to methemoglobin and Heinz bodies, and the RBC is destroyed in the spleen. Spectrin deficiency causes hereditary spherocytosis; pyruvate kinase deficiency is a separate enzyme defect involving ATP rather than redox balance.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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