A Novel Four-Way Translocation t(5;9;22;18)(q31;q34;q11.2;q21) in a Patient with Chronic Myelogenous Leukemia

ABSTRACT

Chronic myelogenous leukemia (CML) is characterized by the presence of the Philadelphia chromosome, which is generated by a reciprocal t(9;22)(q34;q11) translocation. Variant Philadelphia chromosomes, found in 5-10% of CML cases, are a result of translocations involving other chromosomes, in addition to 9 and 22. These four-way Philadelphia chromosome translocations are very rare; only about 60 patients with such chromosomes have been described. Here, we report a CML case with a novel four-way variant Philadelphia chromosome. A conventional chromosome analysis of bone marrow cells revealed a 46,XY,t(5;9;22;18)(q31;q34;q11.2;q21) karyotype, which was confirmed by multicolor fluorescence in situ hybridization. The major BCR-ABL1 fusion gene was detected by reverse transcription-nested PCR. The patient was treated with imatinib. Twelve months after treatment, he demonstrated a complete hematologic response and chromosome analysis showed that he had a normal karyotype.