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': 'Conversion of phenylalanine to tyrosine is hampered in ? \nSelect and explain. \nA. Phenylketonuria, B. Alkaptonuria, C. Maple syrup disease, D. Tyrosinemia', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., PhenylketonuriaPhenylketonuria is characterized by inability of oxidation of phenylalanine into tyrosine.It is an inborn metabolism of phenylalanine, in which there is inability of oxidation of phenylalanine into tyrosine. There is defective function of phenylalanine hydroxylase, which may be due to : ?Classical phenylketonuria (hyperphenylalanemia type I) - Deficiency of phenylalanine hydroxylase.Atypical phenylketonuria (Hyperphenylalanemia type II and III) - Defect in dihydrobiopterin reductase.Hyperphenylalanemia type - IV and V - Defect in dihydrobiopterin synthesis.", 'role': 'assistant'}]