Hereditary hemorrhagic telangiectasia
Hereditary hemorrhagic telangiectasia is a condition characterized by abnormal blood vessels which are delicate and prone to bleeding. Hereditary hemorrhagic telangiectasia is also known as Osler-Weber-Rendu disease.
The term telangiectasia refers to a spot formed, usually on the skin, by a dilated capillary or terminal artery. Telangiectasia is an arterial-venous malformation (AVM) composed of small blood vessels. In hereditary hemorrhagic telangiectasia these spots occur because the blood vessel is fragile and bleeds easily. The bleeding may appear as small, red or reddish-violet spots on the face, lips, inside the mouth and nose, or the tips of the fingers and toes. Besides the skin and mouth, telangiectasias may occur in the gastrointestinal tract (GI tract), the brain, and the lungs. Unlike hemophilia , where bleeding is caused by an ineffective clotting mechanism in the blood, bleeding in hereditary hemorrhagic telangiectasia is caused by fragile blood vessels. However, like hemophilia, bleeding may be extensive and can occur without warning.
Causes and symptoms
Hereditary hemorrhagic telangiectasia, an autosomal dominant disorder, occurs in one in 50,000 people. Recurrent nosebleeds are a nearly universal symptom in this condition. Usually the nosebleeds begin in childhood and become worse with age. A patient may begin to cough up blood or pass blood in stools. The skin changes begin at puberty , and the condition becomes progressively worse until about 40 years of age, when it stabilizes.
When to call the doctor
Parents should notify a doctor if a child's bleeding does not stop, or bleeding is severe, or the child has severe headaches or becomes unresponsive. Frequent nosebleeds should be followed up with the pediatrician.
The physician looks for red spots on all areas of the skin, but especially on the upper half of the body and in the mouth and nose and under the tongue. Bleeding in the GI tract can cause the stool (feces) to be darker than normal.
There is no specific treatment for hereditary hemorrhagic telangiectasia. The bleeding resulting from the condition can be stopped by applying compresses or direct pressure to the area. If necessary, a laser can be used to destroy the vessel. In severe cases, the leaking artery can be plugged or covered with a graft from normal tissue. In some cases, estrogen therapy is used to reduce bleeding episodes.
In most people, recurrent bleeding results in an iron deficiency. It is usually necessary to take iron supplements. Patients have a normal lifespan, and many people are not aware they are affected by the disease until a family is diagnosed.
Because it is an inherited disorder, hereditary hemorrhagic telangiectasia cannot be prevented.
Parents should be aware that frequent nosebleeds are a common sign of hereditary hemorrhagic telangiectasia. Genetic counseling is recommended for those who know the disease runs in their families. There are also support groups for those who are affected by the disease.
Autosomal dominant —A pattern of inheritance in which only one of the two copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. A person with an autosomal dominant disorder has a 50% chance of passing it to each of their offspring.
Chromosome —A microscopic thread-like structure found within each cell of the human body and consisting of a complex of proteins and DNA. Humans have 46 chromosomes arranged into 23 pairs. Chromosomes contain the genetic information necessary to direct the development and functioning of all cells and systems in the body. They pass on hereditary traits from parents to child (like eye color) and determine whether the child will be male or female.
Sutton, Amy L. Blood and Circulatory Disorders Sourcebook: Basic Consumer Health Information about the Blood and Circulatory System and Related Disorders. Detroit, MI: Omnigraphics, 2005.
HHT Foundation International Inc. PO Box 329, Monkton, MD 21111. Web site: http://www.hht.org/web/.
Mark A. Best Dorothy Elinor Stonely