Metabolism USMLE Step 1 Practice Question
A 29 year old woman with severe rheumatoid arthritis develops fatigue and oral ulcers 2 months after starting a new medication. Laboratory studies show hemoglobin 9.8 g/dL, MCV 108 fL, normal methylmalonic acid, and elevated homocysteine. Which of the following enzymes is most likely inhibited by the medication causing her anemia?
Answer choices
- AThymidylate synthase
- BXanthine oxidase
- CDihydrofolate reductaseCorrect answer
- DHypoxanthine guanine phosphoribosyltransferase
- EAdenosine deaminase
- FMethylmalonyl-CoA mutase
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