[Photosensitization and DNA repair. Possible nosologic relationship between Xeroderma pigmentosum and Cockayne's syndrome].

UV-sensitivity is a common feature of several diseases including Xeroderma pigmentosum (XP), Cockayne syndrome (CS) and Bloom syndrome (BS). In 12 children with such diseases, cell viability and DNA repair following UV-irradiation as well as PHA transformation of lymphocytes were studied. In 5 of 6 XP cases, in 1 child with CS and in 1 of 2 children with BS, DNA repair and PHA transformation of lymphocytes showed extremely depressed values. A similar study was performed in 2 children with a rare association of XP and CS. Results suggest a relationship between these 2 diseases