Metabolism USMLE Step 1 Practice Question
A 6 year old boy is brought to clinic because of fatigue, gum bleeding, and pain in both legs. His family recently experienced food insecurity, and his diet has consisted mainly of crackers and processed snacks. Examination shows perifollicular hemorrhages and swollen gums. Defective activity of which of the following enzymes is most directly responsible for this patient's symptoms?
Answer choices
- ADihydrofolate reductase
- BProlyl and lysyl hydroxylaseCorrect answer
- CLysyl oxidase
- DHomogentisate oxidase
- EBranched chain alpha ketoacid dehydrogenase
- FVitamin K-dependent gamma-glutamyl carboxylase
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