Isolation of UV-resistant revertants from a xeroderma pigmentosum complementation group A cell line

Xeroderma pigmentosum (XP) is an autosomal recessive disease. Cells cultured from XP patients are hypersensitive to the lethal effects of UV light. Most XP cells are defective in an early stage in DNA repair of UV light-induced damage. The nature of the genetic defect of the XP syndrome has not been defined. To address this problem, we attempted to isolate UV-resistant cells from a cell line derived from an XP complementation group A (XPA) patient. By using a selection scheme capable of detecting one UV-resistant cell in a population of 10(8) cells, several UV-resistant clones were isolated at frequencies between 1 X 10(-7) and 2 X 10(-8). Here we describe the isolation and initial characterization of these phenotypic revertants.