NIPBL and atrial septal defect: Use of either Sox17-2A-iCre (expressed in endoderm and non-cardiomyocyte mesodermal derivatives) or FoxA2-2A-iCre (expressed both in endodermal and multiple other derivatives) to create Nipbl deficiency also resulted in a high incidence of ASD, about 26% in each case (Fig 5C and 5D).