• 2 of 25 mice exhibit hypoplastic pulmonary artery

• 3 of 25 mice exhibit interrupted aortic arch

• some mutant mice develop atrial septal defects of the primum type

• all mice exhibit septal defects with expressivity varying from primum atrial septal defect to complete AVSD

• some mutant mice develop atrioventricular septal defects of the complete common atrioventricular canal type

• approximately half of affected mutants exhibit unbalanced hypoplastic right ventricle