Constitutive heterozygous GATA2 mutation causes a complex disorder with a wide spectrum of age and phenotype at presentation and is associated with several clinically described syndromes including Emberger syndrome (primary lymphedema and MDS/AML), familial MDS/AML, and MonoMac (monocytopenia with mycobacterium avium complex). The gene discussed is GATA2; the disease is acute myeloid leukemia.