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': 'The genetic defect associated with decreased response to interferon therapy to Hepatitis C is: \nSelect and explain. \nA. IL28B, B. IL15, C. c-KIT, D. NAT2', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Some patients with hepatitis C may not respond well to treatment with interferon as expected. They are harboring genetic variation in IL28B usually. Ref: Harrison, Edition-18, Page-42', 'role': 'assistant'}]