SMAD4 and arteriovenous malformations of the brain: On top of these mutations, studies found additional de novo mutations in some bAVMs, including mutations on ENG, ALK-1, SMAD4, JUP, EXPH5 (encoding exophilin 5), and EPAS1 (endothelial PAS domain protein 1 encoding hypoxia-inducible factor 2-alpha) genes [19,23,27,28,29,30,31,38], adding greater complexity to the currently understood mechanisms of bAVM pathogenesis.