The GATA1 transcription factor is important in the development of erythroid and megakaryocytic lineages. Amino-terminal, small insertion/deletion(frameshift), nonsense and missense mutations of GATA1 have been described in almost all patients with transient abnormal myelopoiesis(TAM) and acute megakaryoblastic leukemia associated with Down syndrome (Trisomy 21)(DS-AMKL). Studies suggest that the cases of TAM which progress to DS-AMKL are associated with the acquisition of additional driver mutations in other genes including the cohesin complex genes as well as CTCF and EZH2. The amino-terminal GATA1 mutations lead to a lack of the N-terminal amino acids and translation from an alternate start codon (methionine at position 84 in exon 3). GATA1 mutations appear to be rare in acute megakaryoblastic leukemia not associated with Down syndrome. GATA1 mutations have also been reported in the context of hereditary myeloid disorders. If clinical findings and family history are concerning for an inherited disorder, then genetic counseling may be helpful, if clinically indicated.