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 crucial role in the development of neutrophils and T cells, as well as stem cell differentiation. Disruptions in GFI1 activity have been linked to immune deficiencies and blood-related cancers, emphasizing its importance in immune and hematologic health.