Metabolism USMLE Step 1 Practice Question
A 9-month-old boy presents with failure to thrive, developmental delay, and recurrent seizures. Physical examination reveals hypothermia (36.2°C), sparse kinky hair, and skin laxity. Vital signs show HR 92/min, RR 22/min, SpO2 98% on room air. Laboratory studies demonstrate serum copper 45 μg/dL (normal 70-150) and ceruloplasmin 8 mg/dL (normal 20-40). Bone radiographs show periosteal spurs consistent with connective tissue involvement. There is no hepatomegaly. Deficiency of which enzyme most directly causes his connective tissue abnormalities?
Answer choices
- ADopamine beta hydroxylase only
- BTyrosinase only
- COrnithine transcarbamylase
- DProlyl hydroxylase
- ELysyl oxidaseCorrect answer
- FCytochrome c oxidase
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