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: Pathology
[{'content': 'This gene mapping indicates: \nSelect and explain. \nA. Klinefelter syndrome, B. Cri du chat syndrome, C. Eagle’s syndrome, D. Down’s syndrome', 'role': 'user'}, {'content': "Answer: D \nExplanation: Down's syndrome, which is due to trisomy of\xa0chromosome 21 (XXX).", 'role': 'assistant'}]