Coexistence of breakpoint cluster region-Abelson1 rearrangement and Janus kinase 2 V617F mutation in chronic myeloid leukemia: A case report

BACKGROUND The Janus kinase 2 (JAK2) V617F mutation is common in patients with breakpoint cluster region-Abelsonl (BCR-ABL1)-negative myeloproliferative neoplasms, including polycythemia vera, essential thrombocythemia and primary myelofibrosis, but is rarely detected in BCR-ABL1-positive chronic myeloid leukemia (CML) patients. Here, we report a CML patient with both a BCR-ABL1 rearrangement and JAK2 V617F mutation. CASE SUMMARY A 45-year-old Chinese woman was admitted to our department with a history of significant thrombocytosis for 20 d. Color Doppler ultrasound examination showed mild splenomegaly. Bone marrow aspiration revealed a karyotype of 46, XX, t(9;22)(q34;q11.2) in 20/20 metaphases by cytogenetic analysis, rearrangement of BCR-ABL1 (32.31%) by fluorescent polymerase chain reaction (PCR) and mutation of JAK2 V617F (10%) by PCR and Sanger DNA sequencing. The patient was diagnosed with CML and JAK2 V617F mutation. Following treatment with imatinib for 3 mo, the patient had an optimal response and BCR-ABL1 (IS) was 0.143%, while the mutation rate of JAK2 V617F rose to 15%. CONCLUSION Emphasis should be placed on the detection of JAK2 mutation when CML is diagnosed to distinguish JAK2 mutation-positive CML and formulate treatment strategies.