[Xeroderma pigmentosum].

Xeroderma pigmentosum(XP) is an autosomal recessive disease that is characterized by hypersensitivity to sunlight with high incidence of skin cancer and that exhibit variable neurological abnormalities in some groups. There are eight different complementation groups in XP; groups A through G and a variant(XP-V). XP-A through XP-G have a defect in nucleotide excision repair(NER), while XP-V has a defect in translesion DNA synthesis. Almost all of genes for XP have been cloned and their functions in the NER mechanism have been progressively unveiled. In this review, the present knowledge of the pathological features and genetic defects in XP has been discussed.