MEF2C and acute lymphoblastic leukemia: Furthermore, the immunophenotypically characterized ETP-ALL overlaps with the immature MEF2C-expressing cluster, suggesting that both may represent a single disease entity. The absence of biallelic deletion (ABD) also represents ETP-ALL and is associated with adverse risk features and patients outcome [12,21]. In a previous study, we showed that ABD and high MEF2C expression are associated with the immature immunophenotype [12].