TBX5 and atrial septal defect: Pathogenic mutations in TLL1 and GATA6 have been identified in families with sporadic ASD4, 5, and mutations in NKX2.5, GATA4, TBX20, MYH6, and TBX5 have been shown to contribute to familial ASD with autosomal dominant inheritance6, 7, 8, 9, 10.