Application of transcriptome sequencing and fusion genes analysis in the diagnosis of myeloid leukemia with normal karyotype

Objective: To analyze the possible fusion genes with high-throughput transcriptome sequencing in myeloid leukemia patients with normal karyotype. Methods: From May 2017 to January 2019, three cases of myeloid leukemia patients with normal karyotype and negative for common fusion genes from the First Affiliated Hospital of Nanchang University were selected as the research objects. The transcriptome sequencing of bone marrow mononuclear cells was performed by high-throughput gene sequencing technology. Defuse software was used to analyze the gene fusion sequence in the transcriptome data, reverse-transcription polymerase chain reaction (RT-PCR) and Sanger sequencing were used to verify the fusion gene with clear pathological significance. Results: All three patients were diagnosed with myeloid leukemia by clinical manifestations, bone marrow cell morphology, immunology, and histochemical staining. Cytogenetic tests showed normal chromosome karyotypes. Fluorescence in situ hybridization and RT-PCR were used to detect BCR-ABL1, PML-RARA, and other common fusion genes. The results were all negative. Transcriptome sequencing and fusion transcripts analysis revealed that these three patients carried rare fusion genes with clear pathological significance, which included BCR-FGFR1, CPSF6-RARG, and NUP98-RARG, respectively. Conclusion: Transcriptome sequencing can accurately analyze rare but pathologically significant fusion genes that may exist in myeloid leukemia patients with normal karyotypes.