TBX5 and Holt-Oram syndrome: Missense mutations of TBX5 have been associated with multiple types of congenital heart diseases (CHDs), such as Holt–Oram syndrome (HOS), atrial septal defect (ASD), and ventricular septal defect (VSD) (Beddington et al. 1992; Horb and Thomsen 1999; Ghosh 2001; Papaioannou 2001; Dreßen et al. 2016).