GFI1 (Growth Factor Independent 1 Transcriptional Repressor) is a gene that encodes a transcriptional repressor involved in regulating hematopoiesis and immune function. It plays a key role in the development of neutrophils and T cells, as well as stem cell differentiation. Disruptions in GFI1 activity have been associated with immune deficiencies and blood-related cancers, highlighting its importance in immune and hematologic health.