PMC8295748_01
(A) Morphological observation showed blasts in a bone marrow smear. (B) Immunophenotype of AML was determined by flow cytometry. (C) Next-generation sequencing revealed a breakpoint in intron 34 of NUP214 and a breakpoint in intron 2 of ABL1, resulting in the NUP214-ABL1 fusion gene.
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Bone marrow (BM) aspiration revealed 78% blast cells ( Figure 1A ). The blast cells were positive for cytoplasmic MPO, CD7, CD13, CD33, CD34, CD38 (dim), CD56 (partial), CD117, CD123, and HLA-DR, and negative for cytoplasmic CD3, cytoplasmic CD79a, CD1a, CD3, CD4, CD5, CD8, CD10, CD11b, CD14, CD15, CD16, CD19 and CD64 by flow cytometry ( Figure 1B ). NRAS (NM_002524.5) had a point mutation (p.G13D). NGS also showed the presence of an NUP214 (NM_005085.4)-ABL1 (NM_007313.2) fusion gene (fusion of NUP214 exon 34 and ABL1 exon 3) ( Figure 1C ).
(A) RT-PCR for the NUP214-ABL1 fusion transcript. The expected product size was 339 bp. (B) Sanger sequencing of the PCR product confirmed the NUP214-ABL1 fusion gene of exon 34 of NUP214 to exon 3 of ABL1. (C) The structure of NUP214-ABL1 fusion protein. PTK, protein tyrosine kinase; NL, nuclear localization; FAB, F-actin binding. (D) FISH showed normal signal pattern using BCR/ABL1 dual-color dual-fusion probe. (E) FISH showed two intact ABL1 signals using an ABL1 break-apart probe.
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TCACGCACCAAGAAGC) and sequencing of PCR products further confirmed NUP214-ABL1 fusion ( Figures 2A, B ). The fusion protein of NUP214-ABL1 was shown in  Figure 2C . No amplification or the split signal of ABL1 was detected ( Figures 2D, E ).