Defect in DNA Synthesis in Skin of Patients with Xeroderma Pigmentosum Demonstrated in vivo

Abstract
Exposure of normal human skin in vivo to ultraviolet irradiation at wavelengths shorter than 320 nanometers stimulated an unscheduled DNA synthesis in all of the cell layers of the epidermis and in the upper dermal fibrocytes. The skin of patients with xeroderma pigmentosum did not show this response. Correlation of these findings with previous tissue culture studies suggests that the defect in repair of the damaged DNA in xeroderma pigmentosum cells occurs in vivo as well as in vitro.