Hereditary hemorrhagic telangiectasia (tuh-lan-jee-uk-TAY-zhuh), also known as HHT or Osler-Weber-Rendu syndrome, is an inherited disorder that affects blood vessels. In most cases, HHT isn't life-threatening. Currently there's no cure, but in many cases the symptoms can be effectively managed.

In people who have HHT, most of the body's blood vessels are normal. But some of the networks of blood vessels that join arteries to veins (capillaries) aren't correctly formed. In small blood vessels, these abnormalities are called telangiectases. When they occur in larger vessels, they're called arteriovenous malformations (AVMs). People who have HHT may have both kinds of malformations.

Telangiectases and AVMs cause health problems because they don't function normally. This can lead to a variety of symptoms depending on where the blood vessel abnormality is located. In some areas of the body — especially the lungs, brain and liver — these blood vessel abnormalities can be serious because they may bleed, don't allow for adequate oxygen levels in the blood, and can increase your risk of brain infections and stroke. Nosebleeds and bleeding within the intestines can also lead to anemia. The severity of HHT often varies significantly from person to person, even within the same family.

Jan. 07, 2013