Here's a summary of the current UWorld USMLE question page: Case: 3-day-old boy with vomiting, poor feeding, worsening lethargy. Sweet-smelling diapers. Normal pregnancy/delivery, exclusive breastfeeding, healthy siblings. Exam findings: Lethargy, dry mucous membranes, generalized hypertonia. Diagnosis: Maple syrup urine disease (MSUD) — deficiency in branched-chain alpha-keto acid dehydrogenase complex (BCKDC), leading to toxic elevation of branched-chain amino acids: leucine, isoleucine, valine. Classic clues: Rapid onset in newborn, sweet/burnt-sugar odor urine. Management: Restrict branched-chain amino acids in diet (leucine, isoleucine, valine) to prevent neurotoxicity. Other answer choices explained: Galactose: Relevant for galactosemia (not this case). Methionine: Restriction for homocystinuria. Phenylalanine: Restriction for phenylketonuria. Tyrosine: Only restricted for rare metabolic diseases. Educational objective: Early presentation, dietary management of MSUD by restricting BCAAs. References & additional notes: Links to academic articles and biochemistry/endocrine subject categorization. Summary in one line: This question covers diagnosis and management of maple syrup urine disease in a newborn, with the key intervention being dietary restriction of branched-chain amino acids (especially leucine).