Cultured Skin Fibroblasts from Patients with Porokeratosis Are Hypersensitive to the Lethal Effects of X‐radiation

Porokeratosis is an autosomal dominant inherited skin disorder. The lesions are characterized by localized abnormal keratinization and may develop into malignant tumors. To determine the cellular basis of the cancer susceptibility associated with this skin condition, we examined the colony‐forming ability of X‐ray or ultraviolet (UV) light irradiated, cultured fibroblasts derived from porokeratosis patients' normal‐appearing skin. Four fibroblast strains derived from four porokeratosis patients' skin were significantly hypersensitive to the lethal effects of X‐radiation. However, they all showed a similar sensitivity to strains from normal donors to 254 nm UV light. The hypersensitivity to X‐ray radiation in cultured skin fibroblasts from porokeratosis patients suggests an inherent instability of cellular DNA and may probably be associated with the cancer‐prone nature of this skin condition.