This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
[{'content': 'In Phenylketonuria the main aim of first-line therapy is \nSelect and explain. \nA. Replacement of the defective enzymes, B. Replacement of the deficient product, C. Limiting the substrate for deficient enzyme, D. Giving the missing amino acid by diet', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In PKU Phenylalanine hydroxylase enzyme is deficient.So alternative pathways are opened. Leading to the formation of Phenylketone,Phenyllactate and Phenylacetate. This can be prevented by limiting the substrate for deficient enzyme.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 236', 'role': 'assistant'}]