What Is Osler-Weber-Rendu Syndrome?
Osler-Weber-Rendu syndrome (OWR) is also known as hereditary hemorrhagic telangiectasia (HHT).
It’s a genetic blood vessel disorder that often leads to excessive bleeding.
According to the HHT Foundation
International, the syndrome affects about one in 5,000 people. However, many
people with the disease don’t know they have it, so this number may actually be
The name Osler-Weber-Rendu syndrome is named for the doctors who
worked on researching this condition in the 1890s. They discovered that issues
with blood clotting don’t cause this condition, which was previously assumed.
Instead, this condition is caused by problems with the blood vessels
In a healthy circulatory system, there are three types of blood
vessels. There are arteries, capillaries, and veins. Blood moving away from
your heart is carried through arteries, which travels at a high pressure. Blood
moving towards your heart is carried through veins, and it travels at a lower
pressure. The capillaries sit between these two types of blood vessels, and the
narrow passageway of your capillaries helps to lower the pressure of the blood
before it reaches the veins.
People with OWR are missing capillaries in some of their blood
vessels. These abnormal blood vessels are known as arteriovenous malformations
Because there’s nothing to lower the pressure of the blood before
it flows into the veins, people with OWR often experience strained veins that may
eventually rupture. When large AVMs occur, hemorrhages can occur. Hemorrhages
in these areas can become life-threatening:
- the brain
- the lungs
- the liver
- the gastrointestinal tract
People with OWR also have abnormal blood vessels called
“telangiectasias” near the skin and mucosal surfaces. These blood vessels are
dilated, or widened, and are often visible as small red dots on the skin
What Are the Symptoms of Osler-Weber-Rendu
Symptoms and signs of OWR and their severity vary widely, even
among family members.
A common sign of OWR is a large red birthmark, sometimes called a
port wine stain. A port-wine stain is caused by a collection of dilated blood
vessels, and it may darken in color as the person ages.
Telangiectasias are another common symptom of OWR. They’re often
small red dots and are prone to bleeding. The marks may appear on young
children or not until after puberty. Telangiectasias can appear on the:
- whites of the eyes
- gastrointestinal system
AVMs can occur anywhere inside the body. The most common sites
- the nose
- the lungs
- the gastrointestinal tract
- the liver
- the brain
- the spine
The most common symptom of OWR is nosebleeds caused by
telangiectasias in the nose. In fact, this is often the earliest symptom of OWR.
Nosebleeds may happen daily or as rarely as twice per year.
When AVMs form in the lungs, they can affect lung function. A
person with a lung AVM may develop shortness of breath. They may cough up blood.
Serious complications from lung AVMs also include strokes and infections in the
brain. People with OWR can develop these complications because without
capillaries, blood clots and infections can travel directly from the rest of
the body to the brain without a buffer.
A person with a gastrointestinal AVM may be prone to digestive
problems, such as bloody stools. These are not generally painful. However, a loss
of blood often leads to anemia. Gastrointestinal AVMs can occur in the stomach,
intestines, or esophagus.
AVMs can be particularly dangerous when they occur in the brain.
When one bleeds, it can cause seizures and minor strokes.
What Causes Osler-Weber-Rendu Syndrome?
People with OWR inherit an abnormal gene that causes their blood
vessels to form incorrectly. OWR is an autosomal dominant disorder. This means
that only one parent needs to have the abnormal gene to pass it on to their
children. OWR doesn’t skip a generation. However, the signs and symptoms may
vary greatly between family members. If you have OWR, it’s possible that your
child could have a milder or more severe course than you.
In very rare cases, a child can be born with OWR even when
neither parent has the syndrome. This happens when one of the genes that cause
OWR mutates in an egg or sperm cell.
Diagnosing Osler-Weber-Rendu Syndrome
The presence of telangiectasias is one indication of OWR. Other clues
that might lead to a diagnosis include:
- frequent nosebleeds
- bloody stools
- having a parent with the syndrome
If you have OWR, your doctor might want to do additional tests.
- A blood
test can check for anemia, or iron deficiency in the blood.
- A CT scan can show internal AVMs, such as in the
lungs, liver, and brain.
- A gastrointestinal doctor can insert a small
camera down your throat to check for AVMs in your esophagus. This is called
- An echocardiogram uses
sound waves to check blood flow in and out of your heart.
If you have OWR, you should be screened for AVMs in the lungs and
brain. This can help your doctor detect a potentially dangerous problem before
something goes wrong. An MRI can screen for problems in the brain. CT scans can
detect lung AVMs.
Your doctor can monitor the ongoing symptoms of this syndrome
through regular checkups.
Genetic testing isn’t
usually needed to diagnose OWR. These tests are expensive and may not be
available in all circumstances. People with a family history of OWR who are
interested in genetic testing should discuss their options with a genetic
Treating Osler-Weber-Rendu Syndrome
The various symptoms of OWR each require their own types of
Nosebleeds are one of the most common manifestations of OWR.
Fortunately, there are several types of treatments that may help. Noninvasive
- using a humidifier to keep the air in your home
or workplace moist
- keeping the inside of your nose lubricated with
- taking estrogen to potentially decrease bleeding
If noninvasive remedies fail, there are other options. Laser therapy heats and seals the
edges of each telangiectasia. However, you may need to have repeated sessions
for lasting symptom relief. Septal
dermoplasty is also an option for people with severe nosebleeds.
The goal of this procedure is to replace the mucous membrane, or the thin
lining of the nose, with a skin graft that provides a thicker lining. This cuts
down on nosebleeds.
More serious surgery may be required for AVMs in the lungs or
brain. The goal is to take preemptive action before there are problems. Embolization is a surgical
process that treats lung AVMs by stopping blood flow to these abnormal blood
vessels. It can be done in a few hours as outpatient surgery. This procedure
involves the insertion of a material, such as a metallic coil, plug or glue,
into the AVM in order to block it off. Surgery is required for brain AVMs and
depends on their size and location.
Embolization is much trickier to perform on the liver. It can
cause serious complications. Therefore, treatment for liver AVMs is targeted
towards symptom improvement. If medical management fails, a person with OWR requires
a liver transplant.
If intestinal bleeding causes anemia, your doctor will
recommend iron replacement therapy.
This will be in pill form unless you’re not absorbing enough iron. In that
case, you may have to take iron intravenously. In serious cases, your doctor
might order hormonal treatment or a blood transfusion.
Dermatologists can treat port-wine marks with laser therapy if
they bleed a lot or you dislike the way they look.
Other Complications of ORW Syndrome
When mouth bacteria enter the bloodstream and pass through a lung
AVM, it can cause a brain abscess. An abscess is a collection of infected
material containing immune cells and pus. This most often happens during dental
procedures. If you have lung AVMs or haven’t yet been screened, talk to your
doctor about taking antibiotics before proceeding with any dental work.
Outlook of Osler-Weber-Rendu Syndrome
Most people with OWR lead perfectly normal lives. The syndrome is
only life-threatening when an internal AVM begins to bleed uncontrollably.
Visit your doctor regularly, so that they can monitor any internal AVMs.