Cockayne syndrome with delayed recovery of RNA synthesis after ultraviolet irradiation but normal ultraviolet survival.

We report a girl with Cockayne syndrome (CS) with atypical cellular features. We studied the ultraviolet (UV)-sensitivity of cultured fibroblast cells derived from this case and male CS siblings as positive controls. Cells from this female with CS displayed normal unscheduled DNA synthesis and repair replication capacity. However, the cells also displayed a less depressed level of RNA synthesis after UV irradiation, compared to control CS cells, and showed normal UV survival. This CS case with early onset of abnormalities had more serious clinical manifestations than the control CS siblings. These cytological results suggest that there is considerable clinical and cellular heterogeneity in CS and that cellular sensitivity to UV might not be as essential for the diagnosis of CS as previously thought.