This signaling is essential for the proper development and maintenance of the vasculature.3–6 In disease, dysfunction of the BMP-9/10 signaling pathway causes hereditary hemorrhagic telangiectasia (HHT).7–11 HHT is characterized by the development of arteriovenous malformations (AVMs), direct connections between arteries and veins without intervening capillaries. This evidence concerns the gene GDF2 and hereditary hemorrhagic telangiectasia.