NKX2-5 and atrial septal defect: In vitro mouse modeling of a heterozygous mutation in Nkx2-5 associated with AV block and ASD showed reduced NKX2-5 nuclear import, downregulation of BMP and Notch signaling, and ultimately dysregulation of genes involved in early cardiomyocyte differentiation and function and reduced cardiomyogenesis [29].