Deficient recovery from potentially lethal damage in some gamma-irradiated human fibroblast cell strains

The repair of potentially lethal damage following treatment with gamma radiation was investigated in human fibroblasts held in a non-cycling state by maintenance in a medium containing 0.5% foetal calf serum. Normal cells were found to be competent in the repair of PLD. Ataxia-telangiectasia cells were deficient as was a heterozygote suggesting that a failure to repair PLD may make it possible to detect such heterozygotes. Fibroblasts from Huntington's disease patients were either slightly or no more sensitive than cells from normal individuals. Cultures from two individuals in the former class showed limited capacity to repair PLD but cells from the latter class were as competent as normals. Thus assays of radiosensitivity where conditions allow for the repair of PLD may maximise small differences in sensitivity. Cells taken from three patients suffering from Basal Cell Naevus Syndrome were also shown to be defective in the repair of PLD. The existence of such a defect may be related to the increased frequency of basal cell cancer observed in exposed fields following irradiation of such individuals.