PAN3–PSMA2 fusion resulting from a novel t(7;13)(p14;q12) chromosome translocation in a myelodysplastic syndrome that evolved into acute myeloid leukemia

Ioannis Panagopoulos, Ludmila Gorunova, Hege Kilen Andersen, Astrid Bergrem, Anders Dahm, Kristin Andersen, Francesca Micci, Sverre Heim

Acquired primary chromosomal changes in cancer are sometimes found as sole karyotypic abnormalities. They are specifically associated with particular types of neoplasia, essential in establishing the neoplasm, and they often lead to the generation of chimeric genes of pathogenetic, diagnostic, and prognostic importance. Thus, the report of new primary cancer-specific chromosomal aberrations is not only of scientific but also potentially of clinical interest, as is the detection of their gene-level consequences. RNA-sequencing was performed on a bone marrow sample from a patient with myelodysplastic syndrome (MDS). The karyotype was 46,XX,t(7;13)(p14;q12)[2]/46,XX[23]. The MDS later evolved into acute myeloid leukemia (AML) at which point the bone marrow cells also contained additional, secondary aberrations. The 7;13-translocation resulted in fusion of the gene PAN3 from 13q12 with PSMA2 from 7p14 to generate an out-of-frame PAN3-PSMA2 fusion transcript whose presence was verified by RT-PCR together with Sanger sequencing. Interphase fluorescence in situ hybridization analysis confirmed the existence of the chimeric gene. The novel t(7;13)(p14;q12)/PAN3-PSMA2 in the neoplastic bone marrow cells could affect two key protein complex: (a) the PAN2/PAN3 complex (PAN3 rearrangement) which is responsible for deadenylation, the process of removing the poly(A) tail from RNA, and (b) the proteasome (PSMA2 rearrangement) which is responsible for degradation of intracellular proteins. The patient showed a favorable response to decitabine after treatment with 5-azacitidine and conventional intensive chemotherapy had failed. Whether this might represent a consistent feature of MDS/AML with this particular gene fusion, remains unknown.