An intragenic ERG deletion (ERGdel) is a marker of an oncogenic subtype of B-cell precursor acute lymphoblastic leukemia with a favorable outcome despite frequent IKZF1 deletions

Oncogenic subtypes in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are used for risk-stratification. However, a significant number of BCPALLpatients are still genetically unassigned. Using array-CGH in a selected BCPALL cohort, we characterized a recurrent V(D)J-mediated intragenic deletion of the ERG gene (ERGdel). A breakpoint-specific PCR assay was designed and used to screen an independent non-selected cohort of 897 children aged 1-17 years treated for BCP-ALL in the EORTC-CLG 58951 trial. ERGdel was found in 29/897 patients (3.2%) and was mutually exclusive of known classifying genetic lesions, suggesting that it characterized a distinct leukemia entity. ERGdel was associated with higher age (median 7.0 years vs. 4.0 years, P=0.004), aberrant CD2 expression (43.5% vs. 3.7%, P