This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiac disorders, Subject name: Pathology
[{'content': 'Which protein is defective most commonly in dilated cardiomyopathy? \nSelect and explain. \nA. Dystrophin, B. Tropomyosin, C. Titin, D. Troponin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In dilated cardiomyopathy, mutations in TTN, a gene that encodes titin (so-called because it is the largest protein expressed in humans), may account for approximately 20% of all cases of DCM. Additionally, mutations affecting the membrane-associated dystrophin protein that couples cytoskeleton to the extracellular matrix are also repoed.', 'role': 'assistant'}]