Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder, affecting approximately 1 in 5000 persons. It is an "equal opportunity disorder"; all ethnicities and both genders are similarly affected.
HHT commonly results from mutations in endoglin (HHT1) or activin receptor-like kinase (HHT2), or occasionally from mutations in Smad4 or other genes. HHT gene mutations lead to development of abnormal vascular structures, ranging from dilated microvessels (telangiectases) to large arteriovenous malformations (AVMs).
The vascular malformations of HHT primarily affect four organ systems: skin/mucous membranes, lungs, brain, and liver. There is a marked variation of disease presentation and severity, even within families sharing the same genetic mutation. Many patients experience only nosebleeds and telangiectases, and have a normal life span. Other patients may harbor lung or brain AVMs, which can cause life-altering stroke, abscess or hemorrhage. The severity of nosebleeds or other obvious symptoms is not predictive of the likelihood of having a pulmonary or cerebral AVM.
Fortunately, accurate screening tests are available to detect pulmonary and cerebral AVMs, and if discovered, the treatments are minimally invasive and effective. Rarer complications of HHT, which also may require treatment, include DVT, symptomatic liver disease, pulmonary hypertension, and spinovascular accidents.
Because of the rarity of the disease, and the need for coordinated treatment among specialists of different organ systems, the HHT Foundation has established several Centers of Excellence for HHT treatment. The UCLA Center of Excellence for HHT includes physician team members from 10 different subspecialties, and offers coordinated, knowledgeable care for HHT, including the full array of counseling, screening, diagnosis, and treatment.