FISH analysis of bone marrow metaphases from Ph-positive ALL patients.

(A) Structure of ABL and BCR genes with composition of the indicated probe systems together with expected hybridization patterns using all 3 probe systems on Ph-positive metaphases. Chromosome 9 homologues are shown on left (normal 9 and derivative 9, respectively) while chromosome 22 homologues are shown on right (normal 22 and Ph, respectively). (B-D) FISH analysis of Ph-positive bone marrow metaphases from ALL patient with deletion of derivative chromosome 9. Each panel shows a metaphase together with an image of the expected hybridization signals (inset). (B) Triple-probe analysis. The blue ASS signal is absent from the derivative chromosome 9 indicating a deletion of chromosome 9 sequences from this chromosome. (C) D-FISH analysis with absence of colocalized signal on der(9) revealing deletion of 9q and 22q sequences from this chromosome. (D) MBCR/ABL analysis. Lack of a BCR signal on the Ph chromosome indicates an m-bcr breakpoint. This signal does not appear on the derivative chromosome 9 consistent with a deletion of this region. Images were captured using an epifluorescence microscope (Axioplan 2, Zeiss, United Kingdom), and SmartCapture 2001 software (Digital Scientific, United Kingdom).