DETERMINATION BY INTERPHASE-FISH OF THE CLONALITY OF ABERRANT KARYOTYPES IN HUMAN HEMATOPOIETIC NEOPLASIAS

Interphase-FISH (fluorescence in situ hybridization) studies have been devoted to the determination of clonality of aberrant karyotypes in h uman leukemia. Various levels of its extent have been examined, includ ing the meaning of a single aberrant karyotype as representing a micro clone, the use of FISH to confirm clonality in bi- or multiclonal leuk emia, the estimation of the residual (aberrant) clone after contrasexu al bone marrow transplantation, and the redetectability in interphase of the abl/bcr rearrangement. The quantitative findings of all these l ines of interphase FISH analyses were based on the comparison with dat a from a large-scale ''control'' study on normal cells using the same DNA probes which have been chosen for the determination of clonality, i.e. centromeric DNA probes for chromosomes #1, #3, from #6 to #12, fr om #15 to #18, #20, X and Y, and a specific probe for the abl/bcr rear rangement. In addition, the validity of interphase-FISH analysis on cl assical bone marrow smears was examined. As a common outcome it was co ncluded that interphase-FISH technique is a valuable tool for defining clonality of karyotypic changes and, as a consequence, yields additio nal prognostic information in many human leukemias. It is recommended to perform interphase FISH in routine cytogenetics of leukemia, whenev er reasonable.