PMC5107624_01
Bone marrow (BM) aspiration, biopsy, karyotyping, reverse transcription (RT)-PCR, and FISH analyses of the present case. (A) BM aspiration (Wright-Giemsa stain, x400) and (B) BM biopsy (hematoxylin & eosin stain, x50) revealed 90% hypercellular marrow with a left-shifted neutrophilic series, an increased number of eosinophilic precursors, and small, hypolobated megakaryocytes. (C) Karyotyping showing t(9;12)(q34;p13); arrows indicate the translocated regions. (D) RT-PCR using BCR/ABL1 and ETV6/ABL1 primer pairs, revealing the 700-bp BCR/ABL1 (lane 1, arrow) and 1,141-bp ETV6/ABL1 (lane 2, arrow) fusion transcripts; left, 100-bp molecular weight marker ladder. The internal control 911-bp band is shown in lane 2. (E and F) FISH analysis using BCR/ABL1 or ETV6/RUNX1 probes, showing no abnormal signal. (G and H) FISH using the mixed BCR/ABL1 and ETV6/RUNX1 probes revealing one yellow fusion signal (ABL1, red; ETV6, green) on 9q34 analyzed in interphase (G) and metaphase (H) cells.
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F1
CML (Fig. 1A, B). Chromosomal analysis of the BM cells demonstrated a balanced t(9;12)(q34;p13) translocation, which was not the Philadelphia chromosome (Fig. 1C). However, reverse transcriptase (RT)-PCR analysis of the BCR/ABL1 fusion transcripts yielded positive results; the reaction product was 700 bp long, indicating positive rearrangement and hence, presence of the P230 chimeric protein at the molecular level (Fig. 1D). To visualize the ETV6/ABL1 fusion signal, we prepared a mixture of two commercially available, locus-specific identifiers: a BCR/ABL1 dual color, dual fusion translocation probe, and an ETV6/RUNX1 extra signal dual color translocation probe (Abbott Vysis) (Fig. 1E, F). Metaphase and interphase FISH with the mixed BCR/ABL1 and ETV6/RUNX1 probes showed one yellow fusion signal at 9q34, which was derived from a green signal from ETV6 and a red signal from ABL1 (Fig. 1G, H). RT-PCR analysis of the ETV6/ABL1 fusion transcript was positive for the 1,141-bp product, indicating a type B fusion (Fig. 1D).