Hereditary Hemorrhagic Telangiectasia

General Information about HHT

Hereditary Hemorrhagic Telangiectasia (HHT) or Osler-Weber-Rendu Syndrome is an inherited disorder that causes abnormal development of some of the blood vessels in the body.  These abnormal blood vessels are called telangiectasias when they develop in the skin and GI tract. Malformations of blood vessels that form in certain organs of the body such as the lungs, brain, and liver are called arteriovenous malformations or AVMs. The most common feature of HHT are nosebleeds which are caused by bleeding telangiectasias in the nose.

HHT has an autosomal dominant inheritance which means that each child of someone with HHT has a 50% chance of inheriting HHT. It is estimated that 1 in every 5000 people in the US has HHT. That means there are approximately 75,000 affected individuals in the US and over 1,000 affected individuals in the state of North Carolina. There are several tests that everyone who is known or suspected to have HHT should have. Since lung and brain AVMs can cause serious damage without warning, and they can be treated, screening (testing) is strongly suggested for these malformations. Both children and adults with HHT are at an increased risk of cerebral hemorrhage, embolic stroke, seizures and brain abscess if brain and lung AVMs are not detected and treated. Other potential complications of HHT can include iron deficiency anemia, low oxygen levels, and pulmonary hypertension. Fortunately, early diagnosis, screening and treatment can help manage and potentially prevent these complications. Unfortunately it is estimated that only 1 out of every 10 people with HHT is aware that they have it.

 

Diagnosis

The diagnosis of HHT can be made clinically by a healthcare provider familiar with HHT using the Curacao diagnostic criteria.

Curacao Criteria

  1. History of chronic and persistent epistaxis (nosebleeds)
  2. Presence of multiple mucocutaneous telangiectasias (red spots)
  3. Presence of organ AVMs
  4. Family history of HHT in a first degree relative (parents, siblings or offspring

The presence of 3 or more criteria makes a definitive diagnosis of HHT while ≤1 criteria make HHT unlikely.

Genetic testing is also used in the diagnosis of HHT.  Approximately 85% of patients with HHT can be identified from genetic testing.

 

Management

Appropriate lifetime management of HHT is essential and involves the following:

  • Treatment of epistaxis (nosebleeds)
  • Management of iron deficiency anemia
  • Periodic screening for AVMs
  • Treatment of any clinically significant AVMs
  • Genetic counseling / genetic testing for affected individuals and family members
  • Preventative measures such as antibiotic prophylaxis before dental procedures.

 

HHT Centers of Excellence

In order to raise the awareness of the disease and to provide comprehensive care for affected individuals, HHT Centers of Excellence were established in the early 1990s. This effort was lead by the HHT Foundation International, a very active and well supported patient advocacy group founded by affected individuals. There are Centers located  throughout the world and currently 14 Centers of Excellence in the US (Yale, Medical College of Georgia at Augusta, Washington University at St. Louis, Salt Lake City, UC San Diego, Oregon Health Sciences Center, Mayo Clinic, and University of Pennsylvania, Johns Hopkins, UCLA, UT Southwestern in Dallas, UNC Chapel Hill, University of Alabama in , University of Wisconsin) – the UNC Center received COE designation in March 2011.

 

For additional information please feel free to contact the UNC HHT Center of Excellence or contact the HHT International Foundation website at  www.hht.org