ACVRL1 and hereditary hemorrhagic telangiectasia: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant vascular dysplasia caused by mutations in genes involved in the TGFβ-BMP receptor signaling pathway: ENG (HHT type 1), ACVRL1 (HHT type 2) and MADH4 (HHT overlap syndrome with Juvenile Polyposis) [1].