NEW TRANSLOCATIONS [T(6,15)(P25,Q22) AND T(6,19)(Q16,Q13.3)] WITH T(9,22)(Q34,Q11) IN A PH-POSITIVE CHRONIC MYELOGENOUS LEUKEMIA

A case with typical features of chronic myelogenous leukemia (CML) wit h two complex-aberrations in addition to the standard t(9;22) is repor ted. Cytogenetic evaluation of the patient's bone marrow cells (BMC) s howed 46,XX,t(6;19) (q16;p13.3),t(9;22)(q34;q11) in 60% of the mitotic cells and 46,XX,idem, t(6;15)(p25;q22) in the remaining 40% dividing cells. The patient's peripheral blood smear exhibited the usual differ ential observed in chronic-phase CML and was clinically indistinguisha ble from patients with the t(9;22) as the only translocation. We perfo rmed Southern blotting on BgllI-digested DNA with the Trans-Probe (OSI ) and in addition to the 4.8-, 2.3-, and 1.1-kilobase (kb) germline fr agments, we detected on additional fragment at 7 kb. This probe spans the entire 5.8-kb M-breakpoint cluster region (BCR), and a single brea kpoint in this region will appear as either one or two additional frag ments. Because only one additional fragment was observed, both cell li nes apparently share the same breakpoint in the ABL/BCR gene. Apparent ly the second aberrant cell line with the additional t(6;15) represent s clonal evolution of the original abnormal clone.