<h4>Background</h4>Capillary malformation-arteriovenous malformation (CM-AVM) is an inherited autosomal dominant vascular disorder associated with RAS p21 protein activator (<i>RASA1</i>) or EPH receptor B4 (<i>EPHB4</i>) mutations. The gene discussed is RASA1; the disease is arteriovenous hemangioma/malformation.