A previous study showed that both heterozygous and homozygous SUMO1 knockout mice exhibit atrial septal defect (ASD)/ventricular septal defect (atrial septal defect) and suffer from high mortality rates; this was rescued by cardiac re-expression of the SUMO1 transgene (Wang et al., 2011). Here, SUMO1 is linked to ventricular septal defect.