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: Medicine
[{'content': 'Mytonic dystrophy is due to- \nSelect and explain. \nA. Expansion in coding region, B. CAG triple nucleotide repeat mutation, C. CTG triple nucleotide repeat mutation, D. Involves chromosome 15', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer-C. CTG triple nucleotide repeat mutationMyotonic dystrophy is associated with a trinucleotide CTG repeat expansion on chromosome 19.This expansion affects the mRNA for the dystrophila myotonia protein kinase (DMPK).Triple nucleotide repeat mutations Normally, a codon is triplet (trinucleotide) (e.g. for CGG it is 5-50 and CGG triplet codon can be repeated, at a stretch, 5-50 times) Non-coding region', 'role': 'assistant'}]