Recurrent Nosebleeds: A Sign of a Genetic Disorder?

At some time, most of us have probably experienced nosebleeds. Perhaps it was in the cold, dry air of winter; maybe it followed a bump to the nose or was due to blowing our nose too hard. If these nosebleeds, also called epistaxis, occurred infrequently or subsided relatively quickly, they were of little concern. However, spontaneous and recurrent nosebleeds, manifesting later in childhood (around 12 years of age), could be one of the most common clinical presentations of a genetic disorder called Hereditary Hemorrhagic Telangiectasia (HHT).

HHT, also known as Osler-Weber-Rendu disease, has been a subject of investigation for over a hundred years. In 1896 Dr. Rendu first described the condition as a hereditary disorder characterized by red spots and nosebleeds. In the early 1900s, Drs. Weber and Osler continued work on the disorder. Only recently has the condition become more clearly defined with genetic testing available.

HHT is not a clotting disorder of the blood but rather a disorder of the actual blood vessels. Normally, arteries transport oxygenated blood, under high pressure, throughout the body. Deoxygenated, low-pressured blood is returned to the heart through veins. There is no direct connection between these two vessel types. Union is through a capillary system.

An individual with HHT has a vessel system that is lacking some capillaries. What often results is that the high- pressured arterial blood enters directly into the weaker walled vein, causing a rupture and bleeding. Telangiectases are vascular lesions due to the dilation of small vessels. Arteriovenous malformations (AVM) is the term used to describe dilation that occurs in larger vessels. Telangiectases tend to appear as red spots near the skin’s surface and mucus membranes of the nose, face, hands and mouth. Large AVMs can be urgent if they occur in the brain, lungs or abdominal area.

HHT affects both males and females from all ethnic groups. It is inherited in a dominant pattern, involving a mutation in one of two genes located on chromosomes 9 and 12. An individual with the disorder carries a 50% risk of passing the mutation to future offspring. It is estimated to have an incidence of 1:10,000 in North America and 1:5,000 worldwide. Clinical testing for one of the mutations became available in November 2003 and is provided at only a few labs in the United States and Canada.