Xeroderma Pigmentosum Variants: Influence of Temperature on Dna Repair

Abstract

Three forms of xeroderma pigmentosum (XP) are currently known: the common form, the de Sanctis-Cacchione syndrome with neurologic involvement, and the XP variant. The first two forms are associated with a reduced capacity of cells to perform excision repair of ultraviolet (UV) damage to DNA. The XP variant clinically resembles the other forms of XP, but cells from these patients have a normal response to UV light when measured at 37°C. Fibroblasts from a patient with the variant type of XP were tested to see if they were still similar to normal cells a reduced temperature. The XP variant was found to be indistinguishable from normal cells, and both carried out similar amounts of DNA repair. This form of XP, then, should be regarded as quite distinct from the other two major forms and probably has an etiology that does not involve a defect in DNA repair.