A 6-month-old infant presents with episodic hypoglycemia, hepatomegaly, and failure to thrive. Liver biopsy shows massive glycogen accumulation with normal glycogen structure. Enzyme assay reveals absent glucose-6-phosphatase activity. Which metabolic pathway is additionally impaired in this condition beyond glycogenolysis?
- A Gluconeogenesis ✓
- B HMP shunt
- C Glycolysis
- D Galactose metabolism
Correct answer: A. Gluconeogenesis
Explanation
Glucose-6-phosphatase (G6Pase) deficiency (Von Gierke disease / GSD Type Ia) blocks both glycogenolysis and gluconeogenesis at their final step — the conversion of glucose-6-phosphate to free glucose. Both pathways converge on G6P before release into blood, so both are effectively blocked. HMP shunt and glycolysis use G6P in other directions and are not impaired in the same clinical sense.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.