question: What is the cause of the disease Xeroderma Pigmentosum?
answer: Mutations in the ERCC1 or ERCC4 genes cause a remarkable array of rare inherited human disorders including specific forms of xeroderma pigmentosum. Individuals with NER-defective xeroderma pigmentosum (XP), in which bulky DNA lesions are not efficiently removed, are cancer-prone and suffer neurodegeneration.