Introduction. We report one elderly patient diagnosed with a rare subtype of acute myeloid leukemia (AML) and also with a very rare fusion gene involving ARHGEF12 (LARG, 11q23.3) and MAPRE1 (EB1, 20q11.21) genes.
Material and methods. Clinical examination and routine analysis were performed including peripheral blood smear, immunophenotyping of the peripheral blood by flow cytometry and several molecular analyses.
Results. Peripheral blood smear showed 80% blasts with round and some with convoluted nuclei, with basophilic cytoplasm, identified as monoblast and the majority of cells as promonocytes. Peripheral blood immunophenotyping was consistent with monocytic differentiation. Molecular analysis was negative for FLT3 ITD, FLT3 D835, NPM1, and DNMT3A R882 mutations. Multiplex ligation-dependent probe amplification revealed no copy number aberration. Ligation-dependent reverse transcription polymerase chain reaction (LD-RT-PCR) analysis identified the presence of one gene fusion between ARHGEF12 (LARG, 11q23.3) and MAPRE1 (EB1, 20q11.21) genes. The patient had no significant comorbidities, the renal function was normal and Eastern Cooperative Oncology Group performance status was 2 at diagnosis and 1 after treatment. She was treated with decitabine. She became transfusion independent and a reduction of the number of blasts was obtained.
Conclusions. The outcome of our AML patient was favorable but other patients with fusion genes involving ARHGEF12 (LARG, 11q23.3) and MAPRE1 (EB1, 20q11.21) should be reported, contributing to a better characterization of the disease, to monitor the minimal residual disease and in the end to more targeted treatment options. LD-RT-PCR represent a valuable multiplex technique for fusion gene analysis.
