HAND2 and aortic stenosis: In the context of the TOF phenotype and the aortic stenosis/coarctation phenotypes, we hypothesize that the HAND2 mutation is solely linked to the phenotype because TBX5 and HAND2 expression is not overlapping in any of the 4 affected structures (ventricular septum, aorta, right ventricle, and outflow tract).