Hereditary hemorrhagic telangiectasia, or Osler-Weber-Rendu syndrome, is a rare autosomal dominant vascular disorder characterized by dysregulated angiogenesis due to abnormalities in the transforming growth factor-β (TGF-β)/bone morphogenetic protein (BMP) signaling pathway that result in mucocutaneous telangiectasias and visceral arteriovenous malformations, leading to recurrent bleeding and multisystem involvement. This evidence concerns the gene TGFB1 and hereditary hemorrhagic telangiectasia.