The Friend of GATA (FOG) family of proteins are a highly-conserved family of large multitype zinc finger cofactors that bind to the amino zinc finger of GATA transcription factors, modulating their activity. GATA proteins are named for the DNA consensus sequence they recognize, (T/A)GATA(A/G). FOG/GATA protein interactions are essential for the development of many tissues. All six GATA family members are capable of interacting with both FOG-1 and FOG-2 (Tsang et al. 1997, Tevosian et al. 1999). Mutations that disrupt binding of GATA-1 to FOG-1 are associated with a syndrome of severe X-linked macrothrombocytopenia (Cantor & Orkin 2005) and in some cases dyserythropoietic anemia (Nichols et al. 2000). In addition to binding GAG proteins, FOGs interact with complexes containing the co-repressor C-terminal binding protein (CtBP) that are thought to coordinate histone modifications leading to a transcriptionally repressed state (Shi et al. 2003).