Metabolism USMLE Step 1 Practice Question
A 5-day-old female newborn develops jaundice, poor feeding, and vomiting after breastfeeding. She becomes lethargic and is admitted to the NICU. Vital signs show temperature 37.2°C, HR 165/min, RR 52/min, BP 55/32 mmHg. Physical examination reveals hepatomegaly and bilateral cataracts. Laboratory studies show total bilirubin 18 mg/dL, normal direct bilirubin, and elevated urine-reducing substances. Blood culture grows Escherichia coli. No acidosis is present. Which enzyme deficiency best explains this presentation?
Answer choices
- AHomogentisate oxidase
- BGalactokinase
- CAldolase B
- DGalactose 1 phosphate uridyltransferaseCorrect answer
- EFructokinase
- FUDP-galactose 4-epimerase
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