Hereditary Hemorrhagic Telangiectasia (HHT)
Hereditary Hemorrhagic Telangiectasia (HHT) is a hereditary disorder that affects blood vessel development in many parts of the body. The arteries and veins are directly joined without the normal collection of capillaries between them. These abnormalities range from small lesions to larger ones. The most commonly affected organs are the nose, skin, lungs, gastrointestinal tract, and brain, in that order.
HHT is an autosomal dominant genetic disorder, meaning that an affected individual needs to have only one copy of the abnormal gene, and only one of the two parents needs to have the gene. (In contrast, cystic fibrosis requires two copies of the abnormal gene, and both parents must have and contribute one.) Both men and women can be affected. As a result, approximately half the children of an adult with HHT will also have HHT.
Translating Research Into Improved Testing
The genetic basis of HHT is becoming better understood through the efforts of clinicians and scientists. Genetic testing is now available thanks to the HHT Foundation International and individual leaders at several HHT centers.
Because HHT can result from many different mutations in at least three different genes, genetic testing is not perfect in identifying the responsible mutation in every family. The diagnosis of HHT should first be confirmed in at least one member of a family based on symptoms and family history. This family member should be tested first to see if the genetic mutation causing HHT can be detected using currently available techniques.
Depending on the test result, a physician can determine whether testing blood samples from additional family members will be helpful. A UT Southwestern Medical Center geneticist can help you and your family members understand the various options.
Evaluating for HHT
At UT Southwestern, our medical screening protocol is aimed at detecting internal arteriovenous malformations (AVMs) before they cause major medical problems. All direct family members of a family with HHT should be screened because there is no relationship between severity of nosebleeds or the number of skin and mucous membrane telangiectasia and the degree of internal involvement.
Because pulmonary AVMs may cause severe complications even if asymptomatic, we use a saline contrast echocardiogram (“bubble echo”) to screen for their presence. If bubbles go from the right to the left side of the heart, there are at least some abnormal blood vessels in the lungs. If positive, we follow with a CT scan to localize the AVMs and plan treatment.
We screen for cerebral AVMs using cerebral MRI. We also screen for anemia with a blood count, and we screen for symptoms and signs of other organ involvement. Because there is currently no treatment that affects the development of intestinal or liver AVMs, we do not perform screening procedures. We begin treatment when symptoms develop.
Treatment Options for HHT
At UT Southwestern Medical Center, a number of treatment options are available for Hereditary Hemorrhagic Telangiectasia, or HHT, and related conditions, including:
- Is usually due to iron deficiency. Most patients respond to oral iron supplements and treatment of nose or GI bleeding. A minority require iron given intravenously at intervals, which can be done in your hometown or at UTSW. A small fraction will require blood transfusions.
- Cerebral AVMs
- Treatment of cerebral AVMs is individualized. Most small, asymptomatic AVMs will be followed. Options include surgery, catheter-guided therapy, and highly localized radiation therapy for those who require treatment.
- Gastrointestinal bleeding
- GI bleeding may respond to local treatment through an endoscope. A variety of medicines may reduce bleeding. Our center anticipates participating in a multicenter clinical trial evaluating bevacizumab (Avastin®) to treat nose and GI bleeding.
- HHT in children
- Children with HHT may be hard to diagnose because nosebleeds may be absent or minor, and skin lesions are often absent or inconspicuous. Our pediatric expert oversees all pediatric evaluations, and our medical geneticist can provide genetic advice and arrange genetic testing.
- Liver AVMs
- Liver AVMs causing symptoms occur in a small minority of patients and may present with signs of heart failure (leg swelling, trouble breathing) or liver disease (abdominal swelling). Medical treatment is highly individualized, and a small number of patients may need liver transplantation.
- Patients with significant nosebleeds will be seen by our otolaryngologist. Therapy will be individualized, and mild nosebleeds may be managed with topical therapy, moisturization, and humidification. Patients with more severe nosebleeds have a complete range of options including laser therapy, embolization therapy, and surgery.
- Pulmonary AVMs
- Most pulmonary AVMs are treated with embolization therapy involving a catheter that enters through the leg; surgery is rarely needed. Most patients will need only one session and will be discharged after several hours. Others may require more than one procedure, and overnight hospitalization is occasionally required. Some AVMs are too small to embolize and will be followed at intervals with CT scan.
The UT Southwestern Hereditary Hemorrhagic Telangiectasia Center is staffed by a team of experienced professionals assembled in response to a regional need for the highest quality HHT care.
Our physicians are experts in HHT treatment and preventative options. If specific problems such as severe nosebleeds, GI bleeding, or pulmonary or neurological symptoms are identified, consultations with various specialists can be arranged during the same visit.
Request an Appointment
To meet with an interventional radiologist at UT Southwestern's facilities in Dallas, or for more information about our services, request an appointment or call 214-645-8300.