Any Brugada syndrome in which the cause of the disease is a mutation in the KCND3 gene. The disease is Brugada syndrome 9 (MONDO_0014621, a Monarch Disease Ontology term). Also known as: BRGDA9, Brugada syndrome caused by mutation in KCND3, Brugada syndrome type 9, KCND3 Brugada syndrome.