Hereditary Hemorrhagic Telangiectasia or Osler-Weber-Rendu Syndrome (HHT)
What is HHT?
Hereditary Hemorrhagic Telangiectasia (HHT) or Osler-Weber-Rendu Syndrome involves a set of problems with the small and medium sized arteries of the body. This syndrome most often affects the lungs, brain, nose, stomach, intestines, or bowel. In this syndrome the problems listed below may be seen.
- The structures of some arteries are not normal.
- There is increased thinness in vessel walls.
- There may be abnormal connections between arteries and veins.
The syndrome was described as early as 1864. It was later named for the doctors who described it and found it to be a syndrome.
The symptoms of this syndrome can range from mild to severe. Some people do not know they have it. In other families, it can be a much greater concern. Problems with symptoms can be prevented with proper medical care.
How do you get HHT?
This syndrome is inherited, which means you are born with it. It is autosomal dominant. This means if one parent of a child has the gene which carries the difference for HHT, then each child born to that couple has a fifty percent chance of having the same gene difference. The children without the gene will not have the syndrome nor will they pass it on to their children. This syndrome is common in persons of Western European origin.
Why are there problems with bleeding?
Arteries are muscular blood vessels. Veins are not muscular blood vessels. The basic problem in HHT is a thinning of the arterial blood vessel walls. These thin vessels are called telangiectases. These arteries are the size of small veins. They have thin walls without smooth muscle. These vessels bleed easily when injured. Without smooth muscle, they also may not contract as they should which can result in prolonged bleeding.
Telangiectasias are not often seen during childhood. They often increase in size and number during adult life. Persons with the syndrome may show an increase in bleeding in their twenties and thirties. This happens as the telangiectasias grow larger and increase in number. You may be able to see the telangiectasias on the skin as they are very tiny and bright red.
Where does bleeding occur?
- Pulmonary Arteriovenous Malformation (PAVM)
This is an abnormal link between an artery and a vein in the lung. These can occur in a small number of persons with HHT. In most cases symptoms do not appear until a person is in his or her 20s or 30s. Symptoms include shortness of breath and coughing up blood. A bluish color of the skin may be seen around the mouth and nail-beds. This occurs when the blood has lower levels of oxygen in it. Symptoms may increase when a woman with this problem is pregnant. Careful follow-up with a health care provider is needed.
- Arteriovenous Malformations
This is an abnormal link between an artery and a vein in the brain. When this occurs there is a concern that there may be a bleeding problem in the brain. Rarely, this bleeding may cause a stroke. Symptoms of these malformations and the bleeding that comes with them include migraine headaches, changes in vision, weakness, and changes in mental status.
- Gastrointestinal Tract (Stomach, Intestines or Bowel)
This type of bleeding occurs in about 20 to 40% of persons with this syndrome. In most cases, it does not appear until 40 or 50 years of age.
- Skin Telangiectasias
These are seen as bright red spots on the skin. They can occur on the cheeks, the lips, the tongue, and sometimes the eyelid. They may bleed. Sometimes they may be cosmetically undesirable. Modern dermatology treatments using laser techniques can remove them.
- Other Body Organs
Other body organs may have problems caused by telangiectasias and arteriovenous malformations.
How is it found?
In most cases, a person must have two of the three symptoms listed below in order for the diagnosis to be made.
• Recurrent nosebleeds (in up to 78% of persons)
• Telangiectasias of the skin
• A parent or other family member has the diagnosis (usually in 80% of cases)
Finding a diagnosis can be hard. This may be because most telangiectasias do not appear until after age 21. At least 10% of persons will not have nosebleeds. The number of people who have this syndrome in the general population is said to be 1-2 per 100,000. Most experts believe this number to be low and believe the number is closer to 10-20 per 100,000.
How is it treated?
The good news is that most of the serious arterial problems can be treated if found early. For the most part treatments involve local measures such as prompt treatment with ice, pressure, rest, and being careful to avoid re-injury to the bleeding site. Laser surgery can be used if lung problems become severe. If the bleeding is severe, a blood transfusion may be needed. Remember, HHT can be treated. Persons with this syndrome can lead mostly normal lives.
American Family Children’s Hospital
Pediatric Hematology/Oncology
(608) 263-6200
The information provided should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Any duplication or distribution of the information contained herein is strictly prohibited.
Last Updated: 06/19/2009
Recreated with permission from University of Michigan, Comprehensive Cancer Center, Hemophilia and Coagulation Disorders Program
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