Homeobox genes play fundamental roles in specifying cell fate and positional identity in embryos. Homeobox gene Csx/Nkx2.5, one of the vertebrate homologues of Drosophila tinman, is expressed in the precardiac mesoderm and in the myocardium of the embryonic and adult heart [, ]and is one of the master regulators of cardiac development, homeostasis and disease [, ]. Csx associates with the transcription factor GATA4 and this interaction may regulate a subset of cardiac muscle-specific genes []. Nkx2-5 regulates the gene encoding the Kcnh2 channel [].Mutations of the human Nkx2.5 gene cause congenital heart disease ASD7, characterised by incomplete closure of the wall between the atria [, , ].
