Next-generation sequencing and molecular cytogenetic characterization of ETV6-LYN fusion due to chromosomes 1, 8 and 12 rearrangement in acute myeloid leukemia

- This is the first report of ETV6-LYN gene fusion in acute myeloid leukemia and broadens the disease association of this genetic aberration.
- Metaphase FISH study shows that the gene fusion occurs through a reciprocal translocation between chromosomes 12p and 1p, to be followed by an inverted insertion of chromosome 8q into derivative chromosome 1.
- The ETV6-LYN is detected by RNA sequencing through a gene panel using NGS, which is advantageous in complex or cryptic chromosomal abnormality since no prior knowledge of the breakpoint is required.

In a newly diagnosed patient with acute myeloid leukemia (AML) and complex cytogenetics and negative for gene mutations associated with myeloid neoplasms, RNA sequencing by next-generation sequencing (NGS) through a large cancer-related gene panel showed ETV6-LYN leukemic fusion transcript. Breakpoint analysis of the NGS reads showed fusion of exon 5 of the ETV6 gene to exon 8 of the LYN gene. Metaphase fluorescence in situ hybridization (FISH) inferred a four-break rearrangement of three chromosomes, namely 1, 8 and 12. First, there was a balanced translocation t(1;12)(p13;p13.2) in which the ETV6 was split between der(1) and der(12). Second, an inverted insertion of 8q12.1~q24.21 into 1p13 occurred, thus bringing ETV6 and LYN into juxtaposition in the correct 5′ to 3′ orientation to produce an in-frame chimeric fusion gene on der(1). Notwithstanding two previous reports of ETV6-LYN fusion in myeloproliferative neoplasms (MPN), we report the first case of this fusion in AML and hence broaden its disease association. We also illustrate the clinical utility of NGS based detection of gene fusion in the setting of complex karyotype or cryptic aberration, since this method does not require a priori knowledge of the translocation partner and exact breakpoints to guide the application of appropriate primers or probes.