Genetic instability in colorectal cancers

Colorectal tumours without microsatellite instability were shown to have a striking defect in chromosome segregation, producing gains or losses in excess of 10^-2 per chromosome per generation. The instability reflected a continuing cellular defect that persisted throughout the lifetime of the tumour cell and was not simply a function of chromosome number. Microsatellite instability behaved as a recessive trait in cell fusion experiments, while chromosomal instability behaved as a dominant one. The authors concluded that persistent genetic instability may be necessary for the development of all colorectal cancers and that it arises through two distinct pathways.