• animals die after birth; 19% die between birth and weaning

• mice exhibit L-loop ventricles and situs inversus in the heart

• in 3 of 17 mice

• observed in 2 of 17 mutant mice

• AVSD with dextrocardia is seen in 2 of 17 mice

• AVSD with levocardia is seen in 3 of 17 mice

• mutant mice develop atrioventricular septal defects with complete penetrance and variable expressivity

• 1 in 17 mice exhibit muscular ventricular septal defect

• mutant mice exhibit situs inversus in the heart