Sister chromatid exchange and chromosome aberration rates in a group of psoriatics before and after a course of PUVA treatment.

Blood was cultured and chromosome preparations were examined for sister chromatid exchanges and chromosome aberrations in eighteen patients receiving photochemotherapy with 8-MOP and UV-A for the treatment of psoriasis, both before starting treatment and again 6 months later. The UV-A was administered both by means of low output (irradiance: 1.1--2.25 mW/cm2) and high output (irradiance: 6.1--7.6 mW/cm2) UV-A radiation cubicles. Irrespective of the intensity of irradiation or the total dose of UV-A administered there was no evidence of chromosome damage in lymphocytes following treatment.