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: Orthopaedics
[{'content': 'Wormian bones are not noted in - \nSelect and explain. \nA. Fibrous dysplasia, B. Osteogenesis inperfecta, C. Cretinism, D. Rickets', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Wormian bones \n\nWormian bones are extra bone pieces that occur within a suture in the cranium.\nThese are irregular isolated bones which appear in addition to the usual centres of ossification of the cranium.\nThey occur most frequently in the course of the lambdoid suture.\nCauses of Wormian bones (Mnemonic - PORKCHOPS)\n\n\nPyknodysostosis\nOsteogenesis imperfecta\nRickets\nKinky hair syndrome\nCleidocranial dysostosis\nHypothyroidism (cretinism) / Hypophosphatasia\nOtopalatodigital syndrome\nProgeria\nSyndrome of Downs\n\n\nWormian bone appears radiographically as islands of ossification in the skull in non ossified membranous bone.\nTo be diagnostic value, the wormian bones should be 4 mm by 6 mm in size, 10 in number and arranged in a mosaic pattern.\nWormian bones are not present in the normal skull.', 'role': 'assistant'}]