CM-AVM is an autosomal dominant disorder caused by heterozygous inactivating mutations in the RASA1 (RAS p21 protein activator 1) gene (CM-AVM1) characterized by the presence of capillary malformations, arteriovenous malformations and fistulas, and occasionally vascular overgrowth [116, 117]. Here, RASA1 is linked to capillary malformation-arteriovenous malformation 1.