Expression of the NUP98/HOXA9 fusion transcript in the blast crisis of Philadelphia chromosome-positive chronic myelogenous leukaemia with t(7;11)(p15;p15).

The t(7;11)(p15;p15) translocation is a recurrent aberration observed in acute myeloblastic leukaemia (AML) and chronic myelogenous leukaemia (CML). It has been shown that the NUP98 gene at 11p15 is fused with the HOXA9 gene at 7p15 in AML with t(7;11). We report the first case with CML expressing the NUP98/HOXA9 fusion transcript. A 27-year-old Japanese man was initially diagnosed as in the chronic phase of Philadelphia-positive CML. At the diagnosis of myeloid blast crisis, the karyotype evolved to 46, XY, t(7;11)(p15;p15), t(9;22)(q34;q11). Reverse transcriptase polymerase chain reaction identified the NUP98/HOXA9 transcript, suggesting that the NUP98/HOXA9 fusion protein could play a critical role in the progression to blast crisis.