Somatic mutations in the GATA1 gene leading to an N-terminal truncated ‘short’ protein (GATA1s) occurred in nearly all Down syndrome patients with acute megakaryoblastic leukemia (DS-AMKL) and transient myeloproliferative disorder (DS-TMD)25, 26. This evidence concerns the gene GATA1 and acute megakaryoblastic leukemia.