RESUMO
In chromosomes of peripheral lymphocytes of 35 patients with multiple sclerosis treated with azathioprine, antilymphocytic globulin or thoracic-duct drainage structural aberrations (breaks and gaps) were found at a significantly high rate. The aberration rates were increased in another ten untreated patients as well, but less so. Patients previously treated had a high aberration rate, too. The B- and C-chromosomes of patients treated with azathioprine were more frequently involved than those of control subjects. The terminal segment of the long arm of chromosome 1 was mostly affected in these patients, while in all groups there was an increase of aberrations in the centre of the long arm of the C-chromosome. The clinical significance of these chromosomal aberrations is not yet clear.