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: Pathology
[{'content': 'Xeroderma pigmentosum is caused due to a defect in: \nSelect and explain. \nA. Nucleotide excision repair, B. Base pair, C. Mismatch repair, D. Translocation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: ● Defective DNA - repair syndromes are a set of syndrome due to a defect in DNA repair genes and resultant DNA instability.\n● These are autosomal recessive in inheritance and include:\nXeroderma pigmentosum\nBloom syndrome\nAtaxia telangiectasia.\n● Whereas HNPCC is associated with inactivation of DNA mismatch repair gene, resulting in increased susceptibility to colon cancer, and cancers of Endometrium, ovary etc.,\n● Example for Base pair defect is Sickle cell anemia; an example for Translocation defect is Philadelphia\nchromosome in CML - t (9:22).', 'role': 'assistant'}]