This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other Autoimmune Disorders, Subject name: Pathology
[{'content': 'Anti-topoisomerase I is marker of: \nSelect and explain. \nA. Systemic sclerosis, B. Classic polyaeritis nodosa, C. Nephrotic syndrome, D. Rheumatoid ahritis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Two ANAs strongly associated with systemic sclerosis are as follows:- One of these,directed against DNA topoisomerase I (anti-Scl 70), is highly specific. Patients who have this antibody are more likely to have pulmonary fibrosis and peripheral vascular disease. The other, an anti-centromere antibody, is found in 20% to 30% of patients, who tend to have the CREST syndrome.', 'role': 'assistant'}]