This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Amino acid Metabolism, Subject name: Pediatrics
[{'content': 'A child has microcephaly, blue eyes, fair skin, and mental retardation; ferric chloride test is positive. What is the likely diagnosis? \nSelect and explain. \nA. Phenylketonuria, B. Homocystinuria, C. Tyrosinosis, D. Alkaptonuria', 'role': 'user'}, {'content': 'Answer: A \nExplanation: -The given scenario suggests diagnosis of Phenylketonuria (PKU). -C/F of Phenylketonuria: Blonde hair, Blue iris, Fair skin Musty/ mousy body odour Microcephaly Intellectual disability due to toxic levels of Phenylalanine and insufficient tyrosine Growth Retardation Dental enamel changes Irritability , Tremors , Convulsions, Hypeonia -OTHER OPTIONS : Homocystinuria- seizures, marfanoid features, ectopia lentis, thromboembolism Tyrosinosis- hepatomegaly, peripheral neuropathy Alkaptonuria- ochronosis, urine turns black on standing, ahritis', 'role': 'assistant'}]