A complex translocation (9;22;16)(q34;q11.2;p13) in chronic myelocytic leukemia

The t(9;22) is present in almost all cases with chronic myelocytic leukemia (CML). Around 5% of these patients show complex translocations involving a third chromosome in addition to chromosomes 9 and 22. All chromosomes have participated in these variants and the BCR-ABL1 hybrid gene is always present. We describe a CML case with a new complex t(9;22;16)(q34;q11.2;p13). Seven months after imatinib treatment a karyotype showed the appearance of a clone with a standard t(9;22) in addition to the clone with the complex translocation. The b3a2 transcript of BCR-ABL1 was detected both at diagnosis and 7 months after therapy. In CML, both complex translocations and standard translocations have the same prognosis. However, these complex variants could contribute to the tumoral evolution by conferring selective advantages that, in turn, cause the preferential manifestation at diagnosis of clones with complex translocations.