科研之友
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摘要
Acute promyelocytic leukemia (APL) is characterized by the generation of the PML-RAR alpha fusion transcript as a result of a reciprocal chromosomal rearrangement, t(15;17)(q22;q12), with break-points within the PML gene and the RAR alpha gene. In a small proportion of APL cases, RAR alpha is fused with a number of alternative partner genes. The signal transducer and activator of transcription 5 beta (STAT5b) is one of the variant partners. Here, we describe one rare case with all-trans retinoic acid (ATRA) unresponsive APL characterized by the STAT5b-RAR alpha fusion transcript. Morphology and immunophenotypic analyses indicated the typical features of APL; however, cytogenetic analysis exhibited a normal karyotype, and importantly, results of inter-phase fluorescence in situ hybridization (FISH) or reverse transcriptase-polymerase chain reaction (RT-PCR) analysis indicated that PML-RAR alpha expression was negative. FISH analysis with the RAR alpha dual-color break-apart rearrangement probe indicated a submicroscopic deletion of the 3' end of one RARA gene. Indeed, the STAT5b-RAR alpha fusion transcript was found in this case by array-based comparative genomic hybridization and nested RT-PCR. To the best of our knowledge, we report here only the sixth APL patient in the world with the STAT5b-RAR alpha fusion transcript. Additional clinical studies concerning the prognosis, response to therapy, and pathogenesis of APL patients with STAT5b-RAR alpha fusion are necessary.
