The first case of six-way complex translocation of t(4;7;9;22;8;14) in a patient with chronic myeloid leukemia

Abstract

In chronic myeloid leukemia (CML), patients exhibit the t(9;22)(q34.1;q11.2) translocation, resulting in the formation of a Philadelphia chromosome (Ph). However, a subset of CML patients display variant complex translocations, characterized by three-way, four-way, and five-way translocations, which have been occasionally associated with a poor prognosis. This case report presents the first case of a t(9;22) variant six-way complex translocation in CML. The R banding chromosome karyotyping technique was used to obtain preliminary karyotyping results, and the multi-probe FISH technique was used to assist in the verification of chromosome results. Both FISH and PCR proved the existence of fusion genes. A 45-year-old male patient admitted to our hospital due to elevated WBC and anemia. Bone marrow smears revealed a significant proliferation of mature granulocytes, accompanied by an increase in eosinophils and basophils. Karyotype analysis indicated abnormalities in six chromosomes, including 4, 7, 8, 9, 14, and 22. Further analysis using FISH technology demonstrated the presence of the BCR::ABL1 fusion gene, as well as the mapping of the BCR (22q11), MYC (8q24), IGH (14q32), D4S163 (4q35.1), and D7S486 (7q31) genes to new chromosomes. Ultimately, the karyotype findings were described as t(4;7;9;22;8;14)(q27;q22;q34;q11;q22;q12). PCR showed that BCR::ABL1 was p210. After treatment with imatinib for 4 months, the patient achieved complete cytogenetic response (CCyR) and early molecular response (EMR). This is the first report of complex chromosomal karyotype involving six-way translocation in CML; the combination of chromosome analysis and FISH techniques is an effective strategy in determining the karyotype result.

Keywords: BCR::ABL1; CML; Six-way translocation; Variant Ph translocation.