Metabolism USMLE Step 1 Practice Question
A 1-year-old girl presents with developmental regression, abdominal distention, and failure to thrive. Vital signs show HR 110/min, RR 28/min, temp 37.2°C. Physical examination reveals hepatosplenomegaly without jaundice. Funduscopic examination demonstrates a cherry red spot. Serum acid phosphatase is markedly elevated at 45 U/L (normal <5). Bone marrow biopsy reveals lipid-laden foam cells. Which enzyme deficiency most likely explains these findings?
Answer choices
- AIduronate 2 sulfatase
- BAcid alpha glucosidase
- CAlpha galactosidase A
- DHexosaminidase A
- ESphingomyelinaseCorrect answer
- FBeta glucocerebrosidase (Gaucher disease)
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