Chromosomal aberrations and sister-chromatid exchanges (SCEs) in patients undergoing long-term Imuran therapy

13 patients treated daily for an extended time with Imuran and prednisone and 4 patients treated in the same way with Imuran only were cytogenetically analysed for the induction of structural chromosomal aberrations and SCEs. There was an increase in the number of aberrations and SCEs in nearly all patients analysed. However, we did not find any dose-dependent cumulative effect on chromosomal damage, with the exception of 1 patient tested in a small group of 4 patients involved in a prospective cytogenetic study, who showed a significant time-dependent increase in the number of aberrations.