Xeroderma pigmentosum variant cells are not defective in the repair of (6-4) photoproducts

Using radioimmunoassays specific for (6-4) photoproducts and cyclobutane dimers, Xeroderma pigmentosum variant cells appear to have a normal capacity for the repair of each of these lesions. However, these assays measure an early stage in the repair pathway and we do not exclude the possibility that repair is not successfully completed following UV irradiation and excision of DNA photoproducts.