This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Mousy odour urine is seen in: \nSelect and explain. \nA. Maple syrup urine, B. Phenylketonuria, C. Isovalericaciduria, D. Cystinuria', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Phenylketonuria is caused by deficiency of phenylalanine hydroxylase & /or dihydrobiopterin (BH2) reductase, which regenerates BH4 from BH2. It presents with mousy (musty) odour in urine and emerald green colour in FeC13 test. The aim of first line therapy is to limit the substrate (i.e. phenylalanine) for deficient enzyme', 'role': 'assistant'}]