Hereditary Hemorrhagic Telangiectasia (HHT)
What is hereditary hemorrhagic telangiectasia (HHT)?
Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder that affects blood vessels. In HHT, also called Osler-Weber-Rendu syndrome, either the small capillaries are abnormal and these are called telangiectasias and/or the capillary connection between arteries and veins are abnormal and these are called arteriovenous malformations. Capillaries are tiny blood vessels. They connect arteries (which carry blood away from the heart) and veins (which return blood to the heart).These abnormal blood vessels are fragile and can burst, causing bleeding (hemorrhaging) and other complications. The symptoms and complications depend on where in the body these abnormal blood vessels form.
Who might get hereditary hemorrhagic telangiectasia (HHT)?
HHT can affect men, women, and children from all racial and ethnic groups. It’s genetic, so it runs in families. The disorder is rare, but it’s also underdiagnosed, meaning many people have it without knowing. It’s estimated to affect 1 in 5,000 people worldwide, but a high percentage aren’t clinically diagnosed.
Symptoms and Causes
What causes hereditary hemorrhagic telangiectasia (HHT)?
HHT is genetic, meaning it’s passed down from parents to children. It’s a dominant disorder, caused by one copy of one abnormal gene from one parent. Hundreds of possible mutations in six different genes have been linked to HHT, but the vast majority of cases are due to mutations in two genes, ENG and ACVRL1. Scientists are still studying the mutations and genes involved.
What are the symptoms of hereditary hemorrhagic telangiectasia (HHT)?
The symptoms of HHT vary from person to person, depending on where abnormal blood vessels develop in the body. Some people may have no significant signs, but others may develop very serious symptoms.
The most common symptom is frequent nosebleeds (epistaxis).
Some people with HHT also might have delicate red spots on certain parts of the body. They may get lighter when you press on them and are common on the:
- Fingers or fingertips.
- Lining of the mouth.
Some people with HHT may also have:
- Anemia (not enough red blood cells).
- Bleeding in the stomach or intestines.
People with HHT may develop abnormalities in larger blood vessels, called arteriovenous malformations (AVMs). AVMs can form in the lungs, brain, spinal cord and liver, and they can cause:
- Blue discoloration of the skin.
- Coughing up blood (hemoptysis).
- Trouble breathing (dyspnea).
Rare but serious complications can occur when an AVM hemorrhages, such as:
- Dizziness, double vision, seizures and strokes, if the condition affects blood vessels in the brain.
- Heart failure, as the heart works harder to provide blood throughout the body, if HHT affects the liver.
- Back pain or numbness in the arms or legs, if HHT affects the spine.
Can I give hereditary hemorrhagic telangiectasia (HHT) to my children?
If you have HHT, there is a 50% chance for each child to inherit it.
Diagnosis and Tests
How is hereditary hemorrhagic telangiectasia (HHT) diagnosed?
Genetic testing can identify HHT, but most people are diagnosed based on clinical information. A healthcare provider will likely:
- Ask detailed questions about your personal medical history.
- Ask questions about your immediate relatives’ medical history, especially your parents, siblings and children.
- Examine your body.
- Order tests to take pictures of your organs.
Your healthcare provider may diagnose HHT if they find at least three of the following:
- Repeat nosebleeds.
- Multiple telangiectasias in the typical locations on the skin.
- Internal telangiectasias or AVMs.
- A family history of HHT.
Management and Treatment
How is hereditary hemorrhagic telangiectasia (HHT) treated?
There is no cure for HHT, but treatments can improve symptoms and reduce the risk of serious complications. Scientists are still studying ways to treat HHT and advances are made in medicines that specifically target the formation of blood vessels.
Your healthcare provider treats you for existing symptoms and tests you for any HHT problems that haven’t shown symptoms yet.
Treatment may include:
- Ablation, a minor surgery to zap an area with a laser to make it stop bleeding.
- Embolization, a minor surgery to block an area that is bleeding or has potential risk for bleeding.
- Iron replacement or blood transfusion to treat anemia.
- Lubrication and moisture for nosebleeds.
- Radiation or surgery to remove AVMs.
- Anti-angiogenic medical therapies with infusions and pills.
You may need to see a specialist for treatment related to specific body systems, such as the liver, lungs, gastrointestinal system and brain.
Can I prevent hereditary hemorrhagic telangiectasia (HHT)?
There is no way to prevent HHT or reduce your risk of getting it. But tell a healthcare provider if your parent, sibling or child has it. That may help you catch it early and prevent complications.
Outlook / Prognosis
What is the outlook for people with hereditary hemorrhagic telangiectasia (HHT)?
People with HHT have an almost average life expectancy. But AVMs in the lungs and brain and chronic bleeding are serious and should be treated.
What can I do about hereditary hemorrhagic telangiectasia (HHT) nosebleeds?
To help prevent nosebleeds:
- Avoid certain medications, such as aspirin and NSAIDs.
- Keep a journal to track if any foods or activities trigger nosebleeds.
- Keep your nose moist and lubricated all the time, using a humidifier, ointments and saline spray, for example.
What else can I ask my healthcare provider about hereditary hemorrhagic telangiectasia (HHT)?
If you’ve been diagnosed with HHT, consider asking your healthcare provider:
- Should anyone in my family get tested?
- Can I play sports?
- Should I avoid any particular activities?
- Should I avoid alcohol, certain foods or any medications?
- What can I do to prevent or stop nosebleeds?
- Is it safe for me to get pregnant?
- When should I seek medical attention for bleeding?
A note from Cleveland Clinic
HHT is a genetic disorder that often goes undiagnosed. Symptoms can range from frequent nosebleeds to serious complications in multiple body systems. If you suspect that you or a family member has HHT, talk to your healthcare provider. Early treatment can prevent complications, and genetic testing can determine what family members are affected.