Levels of some enzymes acting on DNA in xeroderma pigmentosum

We have determined the levels of DNA polymerase, DNA ligase, a DNase acting on single-stranded DNA, an endonuclease making singlestrand breaks in double - stranded DNA and polynucleotide kinase in fibroblasts obtained from nine normal persons and from nine patients with Xeroderma Pigmentosum; the pathological lines belong to the different described clinical forms and to the three different complementation groups described so far. All the enzymes are present in the normal lines and in the Xeroderma lines. The levels are quite variable, but the values obtained in the pathological lines lie within the ones observed in the normal population.