This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Biochemistry
The enzyme defect in von Gierke&;s disease (type-1 glycogen storage disease) is 
Select and explain. 
A. Glycogen phosphorylase, B. Debranching enzyme, C. Phosphoglucomutase, D. Glucose-6-phosphate
D: Glucose-6-phosphate
Answer: D: Glucose-6-phosphate 
Explanation: Von Gierke disease:DiseaseEnzyme deficiencyClinical featuresVon Gierke disease Glucose-6-phosphatase deficiencyGlycogen accumulation in liver and renal tubule cells; hypoglycemia; lactic acidemia; ketosis; hyperlipemiaReference: Harper&;s Biochemistry; 30th edition; Chapter 18; Metabolism of Glycogen