Mutations in several transcription factors such as HAND1, HAND2, TBX5, GATA4, NKX2.5 and TBX20 have been identified in patients affected with distinct congenital heart diseases, such as atrial septal defects (TBX5, GATA4, NKX2.5, TBX20), Tetralogy of Fallot (TBX5, TBX20), ventricular septal defects (HAND2), double outlet right ventricle (HAND1), either syndromic (Holt-Oram; TBX5) or isolated (see for recent reviews [110,111]). The gene discussed is HAND2; the disease is Abnormal cardiac septum morphology.