GATA4 and Tetralogy of Fallot: Deletions and heterozygous loss of function mutations of the GATA binding protein 4 gene (GATA4, OMIM *600576) are already strongly associated with conotruncal and septal heart defects [3,18-23] and it has been proposed that duplication of GATA4 is responsible for the pulmonary atresia and Tetralogy of Fallot found in two of the four published probands with 8p23.1 duplication syndrome [4,5].