G6PD deficiency causes haemolytic anaemia upon exposure to oxidant drugs because:
- A G6PD catalyses the rate-limiting step of HMP shunt, and its absence reduces NADPH production, impairing glutathione regeneration ✓
- B G6PD is needed for direct RBC glycolysis; its absence depletes ATP
- C G6PD is needed for haem synthesis; its absence causes porphyria
- D G6PD deficiency increases G6P, causing osmotic haemolysis
Correct answer: A. G6PD catalyses the rate-limiting step of HMP shunt, and its absence reduces NADPH production, impairing glutathione regeneration
Explanation
G6PD catalyses glucose-6-phosphate → 6-phosphogluconolactone in the HMP shunt, generating NADPH; NADPH is essential for glutathione reductase to maintain GSH. Without GSH, oxidant drugs oxidise haemoglobin to methaemoglobin and cause Heinz body formation, leading to intravascular haemolysis. G6PD deficiency does not affect glycolytic flux significantly and has no role in haem synthesis.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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