In fructose-1,6-bisphosphatase deficiency, hypoglycemia characteristically occurs after ingestion of which substrate?

• A Fructose only
• B Fasting (gluconeogenic substrates: alanine, lactate, glycerol) ✓
• C Galactose ingestion
• D High-fat diet

Explanation

Fructose-1,6-bisphosphatase is a rate-limiting enzyme of gluconeogenesis, converting fructose-1,6-bisphosphate to fructose-6-phosphate. Its deficiency impairs gluconeogenesis from alanine, lactate, pyruvate, and glycerol during fasting, causing lactic acidosis and hypoglycemia. Unlike hereditary fructose intolerance (aldolase B deficiency), ingesting fructose itself does not precipitate the acute crisis in this condition.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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