[GATA1-mutation associated leukemia in children with trisomy 21 mosaic].

Mutations of the hematopoietic transcription factor GATA1 (GATA1s) are pathognomonic in newborn with transient leukemia and children with Down syndrome and myeloid leukemia (ML-DS). Both TL and ML-DS can also occur in children with trisomy 21 mosaic.Between 2002 and 2011, 15 newborns and infants were diagnosed with DS mosaic. 9 of them presented with TL and 8 children suffered from ML-DS; 2 of them with a history of TL. In children without stigmata the special morphology and immunophenotype of blasts triggered the screening for GATA1 mutation and trisomy 21 mosaic.All newborns with TL achieved complete remission (CR). Due to clinical symptoms caused by the leukemic blasts, in 3 children low-dose cytarabine was applied. 1 patient died due to cardiac defect. In all patients GATA 1 s was confirmed. 6 children with ML-DS were initially treated according the AML-BFM protocol. After ML-DS was confirmed, therapy was continued with the intensity reduced schedule according to the ML-DS 2006 protocol. All children are still in CR (follow-up 1.8-7 years, median 2.7 yrs). 2 children with unknown trisomy 21 mosaic were diagnosed as acute megakaryoblastic leukemia (AMKL) and treated according the high risk arm of the AML-BFM 2004 including allogeneic stem cell transplantation in one child). GATA1 mutation was identified retrospectively. Both children are alive in CR.GATA1s associated leukemia has to be excluded in all young children with AMKL (<5 years old) to prevent overtreatment. Treatment with reduced intensity seems sufficient in children trisomy 21 mosaic and ML-DS.