FOXC1 and congenital heart disease: Pivotal to this regulatory network are the Forkhead box (Fox) transcription factors (TFs), proteins characterized by their conserved “forkhead” or “winged-helix” DNA-binding domain [1,2]: at least eight Fox TF-encoding genes (Foxa2, Foxc1, Foxc2, Foxh1, Foxm1, Foxo1, Foxp1, and Foxp4) are required for proper cardiac development in vertebrates [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18], while mutations in four Fox genes (FOXC1, FOXC2, FOXH1, and FOXP1) are associated with human congenital heart defects [19,20,21,22,23,24,25,26].