GATA1 and Down syndrome: Myeloid proliferations associated with Down syndrome, typically associated with somatic exon 2 or 3 GATA1 mutation, continue to encompass two clonal conditions that arise in children with constitutional trisomy 21: transient abnormal myelopoiesis (TAM), which is confined to the first 6 months of life and myeloid leukaemia of Down syndrome (ML-DS).