Sister chromatid exchange and lym phocyte proliferation in a Down syndrome mosaic

Abstract
The number of SCE [sister chromatid exchanges] was compared in the normal and trisomic cell lines of a trisomy 21 mosaic case. In the trisomic cells the SCE-frequency was twice as high as in the normal cells. The mitoses with high numbers of SCE (> 10) were increased 4- to 5-fold. Differential chromatid staining also allowed the determination of mitotic cycle of the mitoses. The percentage of mitoses from the 4th or a later mitotic cycle was significantly higher in the trisomic cell line than in the normal one. The cell cycle time was distinctly shortened in the cells with trisomy 21.