A 25-year-old African American woman develops sudden onset jaundice, hemoglobinuria, and anemia after taking primaquine for malaria prophylaxis. Peripheral smear shows Heinz bodies and bite cells. Which enzyme deficiency accounts for this presentation?

• A Pyruvate kinase deficiency
• B Glutathione reductase deficiency
• C Hexokinase deficiency
• D Glucose-6-phosphate dehydrogenase (G6PD) deficiency ✓

Explanation

G6PD deficiency is an X-linked condition most common in males of African, Mediterranean, and South Asian descent. G6PD is the rate-limiting enzyme of the hexose monophosphate shunt, generating NADPH required to maintain glutathione in the reduced state to protect erythrocytes from oxidative injury. When oxidant drugs (primaquine, dapsone) or infections cause oxidative stress, denatured hemoglobin forms Heinz bodies that are removed by splenic macrophages ('pitted' cells appear as bite cells). The condition is episodic and self-limiting as older enzyme-deficient cells are destroyed and younger cells with residual G6PD survive.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.