Introduction: Heterozygous germline mutations of GATA2 gene (guanine-adenine-thymine-adenine binding protein 2) are hereditary mutations that can be pathogenic, sometimes occurring sporadically, responsible for a florid clinical-biological picture, sometimes serious and quickly leading to the death., Case Reports: We reported two women and one man with germline mutations in the GATA2 gene. The first patient, aged 19, initially presented with monocytopenia and chronic lymphedema of the four limbs, suggestive of Emberger syndrome. The second patient, 28-years-old, presented with a disseminated atypical mycobacterium (Mycobacterium kansasii) infection, raising suspicion of an immune deficiency such as MonoMAC syndrome (deficiency syndrome of dendritic cells, monocytes, B lymphocytes and NK cells). The last patient, 30-years-old, presented with pancytopenia, leading to the diagnosis of a family form of myelodysplastic syndromes and acute myeloid leukemia characterized by a mutation of the GATA2 gene., Conclusions: Each case illustrates a typical clinical presentation of GATA2 deficiency, although the evolution of these syndromes ultimately reveals a complex, heterogeneous and intricate picture of hematological, dermatological, infectious, pulmonary, ENT or oncological symptoms. Mutations in the GATA2 gene remain a diagnostic and therapeutic challenge for the internist, and require multidisciplinary management given the florid picture that can be of interest to all specialties. The clinical spectrum of these GATA2 mutations as well as the latest management recommendations from the recent litterature and the "GATA2 club" are described in this article., (Copyright © 2022 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier Masson SAS. All rights reserved.)