atrioventricular septal defect 4 (Monarch Disease Ontology identifier MONDO_0013747) is any atrioventricular septal defect in which the cause of the disease is a mutation in the GATA4 gene. Also known as: GATA4 atrioventricular septal defect, atrioventricular septal defect caused by mutation in GATA4, atrioventricular septal defect type 4.