This MMP9 expression in bAVM vessels is a sign of ongoing vessel remodeling that might be triggered through the same flow-related mechanisms as in intracranial aneurysms and possibly could explain the formation of intranidal aneurysms and draining venous ectasias that are the most common sites of bAVM rupture [16, 21]. The gene discussed is MMP9; the disease is Dilatation of the cerebral artery.