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: ENT
[{'content': 'Most common cause of syndromic deafness is: \nSelect and explain. \nA. Usher syndrome, B. Waardenburg syndrome, C. Pendred syndrome, D. All of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Pendred syndrome is the most common syndromic form of deafness, accounting for approximately 10% of cases. It presents with goiter and sensorineural hearing loss. Usually, the goiter is evident before pubey, but an adult onset has also been noted. Thyroid function is evenly divided, with 50% euthyroid patients and 50% hypothyroid patients. In most cases, the hearing loss is congenital, bilateral, moderate to profound, and sloping in the higher frequencies. An enlarged vestibular aqueduct is a consistent finding, and Mondini-type malformations have also been associated.', 'role': 'assistant'}]