Metabolism USMLE Step 1 Practice Question
A 2-year-old boy presents with growth delay and progressive abdominal fullness. Vital signs show HR 102/min, BP 95/62 mmHg, RR 20/min, temperature 37.2°C. Physical examination reveals marked hepatomegaly without splenomegaly. Laboratory studies demonstrate fasting hypoglycemia (55 mg/dL), elevated AST/ALT (3× normal), normal serum lactate, and hyperuricemia. Abdominal ultrasound confirms hepatic steatosis. He denies recent infections. Which enzyme deficiency most likely explains this presentation?
Answer choices
- ABranching enzyme
- BDebranching enzymeCorrect answer
- CAcid alpha glucosidase
- DFructose 1,6 bisphosphatase
- EGlucose 6 phosphatase
- FGlucokinase
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