This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Pathology
[{'content': 'BRCA1 gene is located on chromosome: \nSelect and explain. \nA. 17q21, B. 13q12, C. 12q13, D. 21q17', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mutations in BRCA1 and BRCA2 are responsible for 80% to 90% of "single gene" familial breast cancers and about 3% of all breast cancers. BRCA1 is located on 17q21 BRCA2 is located on chromosome 13q12.', 'role': 'assistant'}]