A novel t(6;7)(p24;q21) in a chronic myelocytic leukemia in complete cytogenetic remission after therapy with imatinib mesylate

Emergence of additional cytogenetic clones in chronic myelocytic leukemia (CML) patients who become Philadelphia chromosome–negative (Ph−) after α-interferon therapy (or more recently with imatinib mesylate) have been described. We report here a case of a novel t(6;7)(p21;q23) that developed in a CML patient in complete cytogenetic remission during imatinib therapy. In this case, fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction showed a normal pattern for BCR and ABL genes, suggesting that a different and unrelated clone developed after the disappearance of the Ph chromosome.