A rare case of a three way complex variant positive Philadelphia translocation involving chromosome (9;11;22)(q34;p15;q11) in chronic myeloid leukemia: A case report

Breakpoint mapping of a t(9;22;12) chronic myeloid leukaemia patient with e14a3 BCR-ABL1 transcript using Nanopore sequencing

BACKGROUND

The genetic changes in chronic myeloid leukaemia (CML) have been well established, although challenges persist in cases with rare fusion transcripts or complex variant translocations. Here, we present a CML patient with e14a3 BCR-ABL1 transcript and t(9;22;12) variant Philadelphia (Ph) chromosome.

METHODS

Cytogenetic analysis and fluorescence in situ hybridization (FISH) was performed to identify the chromosomal aberrations and gene fusions. Rare fusion transcript was verified by a reverse transcription-polymerase chain reaction (RT-PCR). Breakpoints were characterized and validated using Oxford Nanopore Technologies (ONT) (Oxford, UK) and Sanger sequencing, respectively.

RESULTS

The karyotype showed the translocation t(9;22;12)(q34;q11.2;q24) [20] and FISH indicated 40% positive BCR-ABL1 fusion signals. The RT-PCR suggested e14a3 type fusion transcript. The ONT sequencing analysis identified specific positions of translocation breakpoints: chr22:23633040-chr9:133729579, chr12:121567595-chr22:24701405, which were confirmed using Sanger sequencing. The patient achieved molecular remission 3 months after imatinib therapy.

CONCLUSIONS

The present study indicates Nanopore sequencing as a valid strategy, which can characterize breakpoints precisely in special clinical cases with atypical structural variations. CML patients with e14a3 transcripts may have good clinical course in the tyrosine kinase inhibitor era, as reviewed here.

Recurrent chronic myeloid leukemia with t (9;22;16) (q34; q11; p13) treated by nilotinib: A case report

RATIONALE

Variant Philadelphia chromosome translocations involving chromosomes other than chromosomes 9 and 22 have been reported in 5% to 10% of patients with chronic myeloid leukemia (CML). Here, a case of CML with a t (9, 22, 16) (q34; q11; p13) translocation, which has never been described, is reported.

PATIENT CONCERNS

A 59-year-old female with dry cough, referred to our hospital, exhibited hepatosplenomegaly, high basophil count, and high platelet count at admission without any other known chronic diseases.

DIAGNOSES

The patient was diagnosed with CML with the translocation t (9;22;16) (q34; q11; p13). The patient was treated with imatinib, a first-generation tyrosine kinase inhibitor (TKI), discontinuously, achieving a complete hematological response for 7 years. Since November 8, 2017, the patient had recurrent fever, and her platelet count rose to 1422 × 10/L. Subsequently, the E279K mutation in the BCR-ABL kinase region was detected.

OUTCOMES

According to a previous report, this mutation confers sensitivity to nilotinib, a second-generation TKI. In the end, the patient received treatment with nilotinib and showed a complete hematological response.

LESSONS

The present study reports a rare case of CML with Ph chromosome and a t (9;22;16) (q34; q11; p13) translocation. For such cases about CML with variant Philadelphia chromosome translocations or BCR-ABL kinase region mutation, TKI may still be valuable.

A novel three-way Philadelphia Variant t(9;22;17)(q34;q11.2;q12) in chronic myeloid leukemia: A case report

Chronic myeloid leukemia (CML) is a hematologic malignancy associated with increased circulating myeloid cells and platelets in the peripheral blood, with accompanying bone marrow hyperplasia. The Philadelphia chromosome, t(9;22)(q34;q11), is present in 95% of CML patients, resulting in constitutive tyrosine kinase activity; however, ~5% of CML patients possess a Philadelphia variant. A novel three-way Philadelphia translocation variant, t(9;22;17)(q34;q11.2;q11.2), was identified in a 54-year old man who presented with leukocytosis, anemia and thrombocytosis that was diagnosed with chronic myeloid leukemia, chronic phase. Cytogenetic analysis by G-banding revealed the presence of a three-way translocation involving the long arms of chromosomes 9, 22 and 17. Fluorescence is situ hybridization utilizing a dual-color fusion probe confirmed the presence of the Bcr-Abl fusion gene.

Atypical Presentation of Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a clonal myeloproliferative disorder characterized by the presence of the Philadelphia chromosome, t(9;22), which is a constitutively active tyrosine kinase that causes excessive proliferation and differentiation of myeloid cells in the bone marrow. Most patients are either asymptomatic or present with fatigue, abdominal fullness, and splenomegaly. This is a case in which a 72-year-old Caucasian male’s initial presentation of CML was new-onset atrial fibrillation, chronic obstructive pulmonary disease (COPD) exacerbation, and pneumonia. The severity of his symptoms of atrial fibrillation and dyspnea complicated his stabilization, which delayed his diagnosis of CML and initiation of tyrosine kinase inhibitor for treatment. Unregulated proliferation of leukemic cells increases blood viscosity and results in aberrations in blood circulation that may result in atypical presenting symptoms in myeloproliferative disease. Thus, it is important to have a high clinical index of suspicion for CML in patients with leukocytosis and concurrent symptomatology that is unusual for leukemia.