A case of pure erythroid leukemia with MYB-GATA1 fusion that developed tumor lysis syndrome with dexamethasone

Panel-based RNA fusion sequencing improves diagnostics of pediatric acute myeloid leukemia

New methods like panel-based RNA fusion sequencing (RNA-FS) promise improved diagnostics in various malignancies. We here analyzed the impact of RNA-FS on the initial diagnostics of 241 cases with pediatric acute myeloid leukemia (AML). We show that, compared to classical cytogenetics (CCG), RNA-FS reliably detected risk-relevant fusion genes in pediatric AML. In addition, RNA-FS strongly improved the detection of cryptic fusion genes like NUP98::NSD1, KMT2A::MLLT10 and CBFA2T3::GLIS2 and thereby resulted in an improved risk stratification in 25 patients (10.4%). Validation of additionally detected non-risk-relevant high confidence fusion calls identified PIM3::BRD1, C22orf34::BRD1, PSPC1::ZMYM2 and ARHGAP26::NR3C1 as common genetic variants and MYB::GATA1 as recurrent aberration, which we here describe in AML subtypes M0 and M7 for the first time. However, it failed to detect rare cytogenetically confirmed fusion events like MNX1::ETV6 and other chromosome 12p-abnormalities. As add-on benefit, the proportion of patients for whom measurable residual disease (MRD) monitoring became possible was increased by RNA-FS from 44.4 to 75.5% as the information on the fusion transcripts' sequence allowed the design of new MRD assays.

Acute myeloid leukemia with t(X;6)9p11;q23);MYB-GATA1 and female sex: GATA1 insufficiency may be insufficient for pathogenesis

Pediatric acute myeloid leukemia (AML) is genetically heterogenous (Olsson et al., 2016). t(X;6)(p11;q23) is a rare but recurrent chromosomal translocation in infant AML thought to be associated with male sex and basophilic differentiation (Dastugue et al., 1997). Here we report molecular characterization of AML with t(X;6)(p11;q23);MYB-GATA1 in two female infants and demonstrate preserved GATA1 expression in the sample tested. These findings further debunk a concept that this fusion was restricted to males, in whom it disrupts the only copy of the X-linked GATA1 gene, causing presumable complete loss of GATA1 function. Our data also demonstrate the power and efficiency of RNA sequencing for subclassification of leukemia on a clinically relevant timeline.