Chromosomal abnormalities in 38 CML cases of various phases

Objective To study the genomic abnormality underlying the blast crisis of chronic myeloid leukemia(CML). Methods 15 CML patients in blast crisis (BC), 3 in accelerated phase (AP) and 20 in chronic phase (CP) were analyzed by conventional cytogentics, comparative genomic hybridization (CGH) and dual color chromosomal painting.Results Philadelphia (Ph) chromosome was identified in every case studied. Only 5 among 20 CP patients had additional abnormalities while 12 out of 14 patients with disease progression (BC+AP) showed extra numerical and/or structural chromosmal aberrations. Cytogenetically, the most common chromosome gains during BC and AP were double or triple Ph chromosome(5/14), trisomy 8(5/14), trisomy 7(1/14) and 17(1/14). Three cases showed the same region being involved in translocations t(1;17)(q12 21;q10),t(1;10)(q12 21;q26) and t(1;11)(q12 21;p15). CGH analysis detected genetic imbalances in 8 cases. In one case, a very complex chromosmal translocation del(3), del(6)(q13 21), der(6)t(17;3;6), der(17)t(6;17) was characterized by chromosomal painting.Conclusion We find that the combined use of CGH, chromosomal painting, and classic cytogenetic analysis allows a better evaluation of the genomic aberration involved in CML blastic transformation, and offers new directions for its further molecular investigation.