[Identification of marker chromosomes and complex chromosomal translocations, using non radioactive in situ...

We describe five patients with hematological malignancies in which fluorescence in situ hybridization technique (FISH) has been combined with classical cytogenetic study for characterizing chromosomal abnormalities. Three of them were chromosome Philadelphia positive; using a 22 chromosome painting probe it was confirmed the presence or absence of a variant complex translocation. In patients 4 and 5, the karyotype showed a marker chromosome which was definitively identified by FISH as a deletion of X chromosome and a 18 ring chromosome, respectively. The value of this methodology in the cytogenetic diagnosis of hematological malignancies is commented.