Prognostic value of structural chromosomal rearrangements and small cell clones with high hyperdiploidy in children with acute lymphoblastic leukemia.

Z. Zemanova, K. Michalova, L. Sindelarova, P. Smisek, J. Brezinova, S. Ransdorfova, V. Vavra, A. Dohnalova, J. Stary

In this study, 107 children with acute lymphoblastic leukemia (ALL) were analysed for the presence of hyperdiploidy by cytogenetics and interphase fluorescence in situ hybridisation (I-FISH). Structural aberrations in hyperdiploid cells were investigated by multiple colour FISH (mFISH). Clones with high hyperdiploidy (>50 chromosomes) (HeH) were found in 46 patients (43%). In nine of these (20%), the abnormal clone was present in <20% of the total cell population. There was no significant difference in EFS between those patients with HeH in 2.5-20% or >20% of cells. Structural rearrangements in the HeH clone were found in 10 patients (22%). In this study, HeH karyotypes containing structural aberrations were an indication of a poor prognosis in childhood ALL.