ELEVATED CHROMOSOME ABERRATION FREQUENCY AFTER X-RAY-EXPOSURE OF CULTURED FIBROBLASTS DERIVED FROM PATIENTS WITH POROKERATOSIS

Porokeratosis (PK) is a rare genetic skin disorder inherited as an aut osomal dominant trait and regarded os a disease predisposing to cancer . To evaluate chromosomal radiosensitivity of PK cells, we examined ch romosome aberration frequency after X-irradiation of cultured skin fib roblasts derived from PK patients and controls. Without X-ray exposure , frequencies of chromosome-type aberrations (exchanges or deletions) were not different between the patients and controls. Following X-ray irradiation, frequencies of deletions in the patient group were signif icantly increased, whereas those of exchanges were not elevated. No di fferences in chromatid-type aberration frequency were found between th e patients and controls with or without exposure to X-ray. The observe d radiosensitivity, though not as high as in ataxia telangiectasia (AT ) cells, agrees well with the previously reported higher radiosensitiv ity of PK fibroblasts in survival analysis.