Here, we describe a young adult with GATA2 deficiency presenting with <i>Legionella</i> pneumonia, COVID-19, and HLH with underlying <i>SF3B1</i>-mutated myelodysplasia that responded successfully to allogeneic hematopoietic stem cell transplantation. The gene discussed is SF3B1; the disease is Myelodysplasia.