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What

Osler-Weber-Rendu Syndrome is a disorder that affects the formation of blood vessels. Arteries and veins connect to each other without the normal intermediates (capillaries) and form structures known as arteriovenous malformations. Small arteriovenous malformations called telangiectases are usually present near the skin surface and in mucosal membrane areas, especially the nose and mouth. Larger arteriovenous malformations may occur in organs, such as the brain, liver, lungs, and digestive tract. Slight injury to these areas typically causes bleeding.

Who

The prevalence of Osler-Weber-Rendu Syndrome is variable internationally, but is estimated to be at approximately 1 out of 10,000 people in the United States. It has been found in all races and most ethnic groups and affects males and females equally.

Signs and Symptoms

Children with Osler-Weber-Rendu Syndrome will have at least two of the following findings: • Recurrent and spontaneous nosebleeds, usually around the age of 12 years • Arteriovenous malformations in the liver, lungs, brain, digestive tract, or spine • Telangiectases (small, red, and spider-like lesions) of the skin or mucosal tissue, especially in the nose and mouth. Arteriovenous malformations (AVMs) of the liver may lead to biliary disease which affects the production of bile or portal hypertension (increased pressure in the portal vein resulting from blockage of blood flow in the liver). AVMs of the lungs may lead to exercise intolerance, breathing difficulties, or cyanosis which is a bluish or grayish coloring of the skin due to lack of oxygen. AVMs in the brain can cause headaches or seizures. AVMs in the digestive tract can cause internal bleeding which may result in bloody stool. Fatigue can also occur due to anemia from excessive bleeding.

Possible Causes

Osler-Weber-Rendu Syndrome is a genetic disorder that has an autosomal dominant inheritance pattern. A child receives a mutated gene from one parent, which is enough to become affected. Two causative genes have been identified: the endoglin gene on chromosome 9 and ALK1 on chromosome 12. Both genes are involved in making the tissue that forms the walls of bloods vessels. When these genes are mutated, blood vessels are not formed correctly. Weaknesses in the blood vessel walls can rupture easily, leading to the loss of blood.

Diagnosis

Diagnosis is made through the presence of at least three of the following: • Family history of Osler-Weber-Rendu Syndrome in a first-degree relative (mother, father, or sibling) • Spontaneous and recurrent nosebleeds. • Mucocutaneous (mucous membranes and skin) telangiectases, usually in the nose and mouth or on the fingers and lips. • Arteriovenous malformations in the organs, especially the liver, lungs, brain, digestive tract, and spine.

Treatment

There are currently no cures for Osler-Weber-Rendu Syndrome. Management is aimed towards reducing the number of bleeding events. Air humidification may help moisten the nasal mucous membranes, thereby reducing the number of nosebleeds. Medications, such as oral contraceptives and aminocaproic acid, may also help reduce the number of bleeds from the nose and mouth. Iron supplementation is sometimes needed to treat anemia from excessive blood loss. Folate supplementation may be needed because the body is required to produce a great number of red blood cells to replace the ones that are lost during hemorrhages. After a definitive diagnosis of Osler-Weber-Rendu Syndrome is made, it is very important to have imaging tests (computed tomography or magnetic resonance imaging scan) of the major organs done. This would identify any large arteriovenous malformations the child may have. There may be several complications due to these AVMs. Liver AVMs can cause liver or heart failure, and lung AVMs can lead to infections in the brain. AVMs may also become large enough that they require surgical intervention.

Prognosis

The prognosis of Osler-Weber-Rendu Syndrome is good with most patients having normal life expectancies.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

The Hereditary Hemorrhagic Telangiectasia Foundation
This organization’s mission is to provide information and support for individuals and families with Osler-Weber-Rendu Syndrome. They also provide updated news about current research projects.

MedlinePlus
This article provides a general overview of the syndrome.

Telangiectasia Self Help Group
This webpage provides information about the syndrome. It also has links to other organizations’ websites.

Orphanet
Nice, centralized resource.

Google Search for Osler-Weber-Rendu Syndrome

References and Sources

Guttmacher AE and McDonald J (2004). Hereditary Hemorrhagic Telangiectasia. www.genetests.org/profiles/hht Soriano PA, Petros J, and McKinsey JF (2003). Osler-Weber- Rendu Disease. www.emedicine.com/med/topic2764.htm