High incidence of the ETV6/RUNX1 fusion gene in paediatric precursor B-cell acute lymphoblastic leukaemias with trisomy 21 as the sole cytogenetic change: a Nordic series of cases diagnosed 1989-2005..     ///    The occurrence of ETV6/RUNX1 was determined in 66 childhood ALLs with an acquired +21 and a chromosome number <51.     ///    "Thus, the prognostic impact of +21 is not attributable to cryptic ETV6/RUNX1.. "    ///     Trisomy 21 is common in ETV6/RUNX1-positive acute lymphoblastic leukaemia (ALL).     ///    ETV6/RUNX1 was found in 45% of cases and in the majority (10/18. 