Any of a number of the
chromosomal mutations called
translocations, where a segment of
DNA abnormally becomes attached to the wrong
chromosome, which results in two non
homologous chromosomes being able to
cross over, something which normally can occur only between homologous chromosomes.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.