Adriamycin-induced chromosome damage: elevated frequencies of isochromatid aberrations in G2 and S phases.

Analysis of chromosomes from cells treated with adriamycin during G2 and S phases showed a high frequency of isochromatid-type of breaks, in addition to the expected chromatid breaks. These are interpreted as independent breaks on sister chromatids because of preferential effects of the drug in specific chromosome regions. The break points are likely to be different, but morphologically such breaks would be indistinguishable from isochromatid or chromosome breaks.