Amplification of BCR-ABL rearrangement in atypical Philadelphia chromosome: A new variant detected by fluorescence in situ hybridization in one case of acute lymphoblastic leukemia

We report on a 67-year-old woman with acute lymphoblastic leukemia (ALL) wh o was supposed to have a variant Philadelphia (Ph) translocation identified by conventional cytogenetic techniques. Fluorescence in situ hybridization (FISH) analysis demonstrated the presence of an amplification of BCR-ABL r earrangement at locus 22q11. This is the first observation, to our knowledg e, of a duplicated BCR-ABL chimeric gene within the derived chromosome 22 i n ALL. Our observation supports the possibility of detecting a variant Ph c hromosome at the single-cell level by FISH analysis. (C) Elsevier Science I nc., 1998.