You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is A 10 year old child experiences recurrent skin lesions on her face and upper extremities that rapidly progress to cancer. Xeroderma pigmentosa is considered a possible differential. Which of the following is defective in that case and explain in detail?
UV rays damage DNA by forming thymidine dimers. This is repaired by the body by nucleotide excision repair. Main enzyme of this mechanism is UV-specific endonuclease.