Pii: S0165-4608(00)00370-8

An unusual cytogenetic rearrangement, described as ins(22;9)(q11;q34q21), was detected in a 49year-old male patient diagnosed with chronic myeloid leukemia (CML). Reverse transcriptase polymerase chain reaction (RT-PCR) revealed a b3a2 fusion transcript. In order to confirm the cytogenetic findings and fully characterize the inverted insertion, we performed fluorescence in situ hybridization (FISH) assays using locus-specific and whole chromosome painting probes. Our FISH analysis showed the presence of the BCR/ABL fusion gene, verified the insertion and determined that the breakpoint on chromosome 22 where the insertion took place was located proximal to the BCR gene and distal to the TUPLE1 gene on 22q11. © 2001 Elsevier Science Inc. All rights reserved.