Metabolism USMLE Step 1 Practice Question
A 7-year-old boy presents with progressive developmental delay, aggressive behavior, and coarse facial features. Vital signs show BP 95/60, HR 102, RR 22, Temp 37.2°C, SpO2 98% on room air. Physical examination reveals hepatosplenomegaly without jaundice. Slit lamp examination shows clear corneas. Recent laboratory studies demonstrate elevated urinary heparan sulfate and normal serum mucopolysaccharide levels. Which enzyme deficiency most likely explains this clinical presentation?
Answer choices
- AAlpha L iduronidase
- BGalactocerebrosidase
- CIduronate 2 sulfataseCorrect answer
- DArylsulfatase A
- ESphingomyelinase
- FHeparan-N-sulfatase (Sanfilippo type A)
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