In another mouse model with double deficiency of Cx40/Cx45 (Cx40−/−/Cx45+/−), various cardiac defects occurred, including VSD, ventricular hypertrophy, AVSD, atrial dilatation, and abnormal myocardial arrangement, which resulted in mortality during embryogenesis and after birth [88]. Here, GJC1 is linked to familial atrioventricular septal defect.