The finding that the Ras-GAP, RASA1 (p120-GAP), is mutated in several distinct vascular anomalies [24], [25] including capillary malformation-arterial venous malformations and Vein of Galen aneurysms supports this hypothesis, though it is currently unclear if the loss of RASA1 is sufficient to result in Ras activation. This evidence concerns the gene RASA2 and vein of Galen aneurysm.