This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetic and genetic disorders, Subject name: Pediatrics
[{'content': 'Which of the following is not observed in cri-du-chat syndrome? \nSelect and explain. \nA. Hypeonia, B. Characteristic shrill cry, C. Microcephaly, D. Mental retardation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hypotonia is seen in cri-du-chat syndrome, not hypeonia Cri-du-chat syndrome occurs due to deletion of chromosome 5p Main features: Hypotonia Characteristic shrill cry (cat-like cry) in the first few weeks of life) Microcephaly Hypeelorism Bilateral epicanthal folds High-arched palate Wide and flat nasal bridge Intellectual disability Ref: Nelson textbook of pediatrics 21st edition Pgno: 666', 'role': 'assistant'}]