Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Rendu-Weber syndrome, is a genetic condition which affects the blood vessels. In HHT, there are abnormal connections between some blood vessels. HHT is characterized by one or more of the following:

About one in every 5,000 to 10,000 people have HHT. HHT is often under-diagnosed because people and doctors are not familiar with the symptoms.