Increased sister-chromatid exchange frequency in patients receiving sulphasalazine therapy for ulcerative colitis.

Sister-chromatid exchange and micronucleus frequencies are reported for lymphocytes cultured in vitro from 15 patients receiving sulphasalazine therapy for ulcerative colitis and 15 controls matched for age and sex. While the patients did not differ from matched controls for micronucleus frequency there was a substantial rise in their sister-chromatid exchange frequency. This evidence of DNA damage is discussed in relation to the known cancer risk that ulcerative colitis carries and the possibility of an increased mutation rate in the germ cells of those receiving sulphasalazine therapy.