A Rare BCR::SPECC1L::ABL1 Fusion in a Pediatric Chronic Myeloid Leukemia Patient.

BACKGROUND

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm typically defined by BCR::ABL1 p210 fusions isoforms.

OBSERVATIONS: An 8-year-old female CML patient harbored a typical t(9;22)(q34;11) Philadelphia chromosome and BCR::ABL1 fusion by conventional karyotyping and FISH but lacked BCR::ABL1 p210 fusion transcripts by RT-PCR. Targeted next-generation sequencing (NGS) revealed BCR::SPECC1L::ABL1 fusion transcripts predicted to encode an in-frame BCR-exon-8::SPECC1L-exon-4::ABL1-exon-2 fusion protein retaining the tyrosine kinase domain. FISH and NGS were used for therapeutic imatinib monitoring given this atypical isoform.

CONCLUSIONS

This case highlights the role of multimodal molecular diagnostics to diagnose and monitor pediatric CML patients with atypical fusion isoforms.