Specificity of melphalan-induced rearrangements and their transmission through cell divisions

The clastogenic effect of melphalan, an alkylating agent frequentlyused in chemotherapy, was investigated using chromosomes fromhuman lymphocytes, two and three cell cycles after treatmentin vitro. Chromosome aberrations were much more frequent thanchromatid type anomalies. Unbalanced rearrangements, i.e. deletions,dicentrics and complex rearrangements (in decreasing order ofoccurrence), were quite frequent and balanced rearrangements,such as reciprocal translocations and inversions, were quiterare. Deletions principally affected chromosomes 9, 5, 7 and11. By comparison to the results obtained at first divisionafter treatment, the relative frequencies of del(5) and del(20)increased with the number of cell divisions. Thus, these deletionswere poorly eliminated by selection. This finding may be relatedto the fact that del(5) and del(20) are frequently observedin premalignant haemopathies. ¹To whom correspondence should be addressed