Hereditary hemorrhagic telangiectasia (HHT), also called Osler-Weber-Rendu syndrome, is a genetic disorder that affects blood vessel formation. People with HHT develop small lesions called telangiectases, which can burst and bleed. Frequent nosebleeds are common, but telangiectases in other areas of the body can cause serious complications.
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.
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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.
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.
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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:
Some people with HHT may also have:
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:
Rare but serious complications can occur when an AVM hemorrhages, such as:
If you have HHT, there is a 50% chance for each child to inherit it.
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Genetic testing can identify HHT, but most people are diagnosed based on clinical information. A healthcare provider will likely:
Your healthcare provider may diagnose HHT if they find at least three of the following:
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:
You may need to see a specialist for treatment related to specific body systems, such as your liver, lungs, gastrointestinal system and brain.
There is no way to prevent HHT or reduce your risk of getting it. But tell your healthcare provider if your parent, sibling or child has it. That may help you catch it early and prevent complications.
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.
To help prevent nosebleeds:
If you’ve been diagnosed with HHT, consider asking your healthcare provider:
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.
Last reviewed on 03/18/2021.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy