TBX5 and familial dilated cardiomyopathy: TBX20 protein presents strong transcriptional activation and repression domains, and it interacts physically, functionally, and genetically with other cardiac developmental transcription factors, including NKX2-5, GATA4, GATA5, GATA6, and TBX5, which are associated with CHD and have also been linked to DCM/LVNC in recent years.22–26 Different growth factors involved in cardiac chamber development, ventricular trabeculation, and valvulogenesis upregulate and downregulate TBX20 expression.