Description of an Institutional Cohort of Myeloid Neoplasms Carrying ETV6-Locus Deletions or ETV6 Rearrangements.

The gene encoding for transcription factor ETV6 presents recurrent lesions in hematologic neoplasms, most notably the ETV6-RUNX1 rearrangement in childhood B-ALL. The role of ETV6 for normal hematopoiesis is unknown, but loss of its function probably participates in oncogenic procedures. In myeloid neoplasms, ETV6-locus (12p13) deletions are rare but recurrent; ETV6 translocations are even rarer, but those reported seem to have phenotype-defining consequences. We herein describe the genetic and hematologic profile of myeloid neoplasms with ETV6 deletions (10 cases), or translocations (4 cases) diagnosed in the last 10 years in our institution. We find complex caryotype to be the most prevalent cytogenetics among patients with 12p13 deletion (8/10 patients), with most frequent coexisting anomalies being monosomy 7 or deletion 7q32 (5/10), monosomy 5 or del5q14-15 (5/10), and deletion/inversion of chromosome 20 (5/10), and most frequent point mutation being TP53 mutation (6/10 patients). Mechanisms of synergy of these lesions are unknown. We describe the entire genetic profile and hematologic phenotype of cases with extremely rare ETV6 translocations, confirming the biphenotypic T/myeloid nature of acute leukemia associated to ETV6-NCOA2 rearrangement, the association of t (1;12) (p36; p13) and of the CHIC2-ETV6 fusion with MDS/AML, and the association of the ETV6-ACSL6 rearrangement with myeloproliferative neoplasm with eosinophilia. Mutation of the intact ETV6 allele was present in two cases and seems to be subclonal to the chromosomal lesions. Decoding the mechanisms of disease related to ETV6 haploinsufficiency or rearrangements is important for the understanding of pathogenesis of myeloid neoplasms and fundamental research must be guided by observational cues.