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': 'Myotonic dystrophy is inherited in chromosomes - \nSelect and explain. \nA. 21, B. 20, C. 19, D. 24', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Myotonic dystrophy is associated with a trinucleotide CTG repeat expansion on chromosome 9.\nThis expansion affects the mRNA for the dystrophila myotonia protein kinase (DMPK).\n\nMyotonic dystrophy \n\nThe characteristic feature of myotonic dystrophy is myotonia, i.e., the sustained involuntary contraction of a group of muscles.\nOf all the dystrophies, only myotonic dystrophy shows pathological changes in the intrafusal fibres of the muscle spindles.\nExtra-muscular abnormalities are : -\n\n\nCataract\xa0\xa0\xa0\xa0\xa0\xa0\nFrontal baldness\nGonadal atrophy\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\nDM\nDementia\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0\nDecreased IgG', 'role': 'assistant'}]