Few people are familiar with HHT, an uncommon blood vessel disorder affecting about 1 in 5000 people around the world. So today I’ll introduce you to HHT—what it is and when to get tested for it.
What is HHT? HHT stands for Hereditary Hemorrhagic Telangiectasia—a mouthful of medical terminology! Here’s what it means:
Hereditary (genetic; inherited)
Hemorrhagic (causes bleeding)
Telangiectasia (abnormal blood vessel)
In other words, HHT is inherited; it causes bleeding; and the bleeding comes from abnormal blood vessels. HHT is caused by a mutation in one of several genes related to blood vessel development. If you have HHT, each of your children has a 50% chance of inheriting the disease. Only some blood vessels in people with HHT are abnormal or malformed. In these malformations, there is a direct connection between an artery and a vein, while normal capillaries (the smallest blood vessels) are missing. These malformations commonly occur in nose, gastrointestinal tract (gut), or on the skin (where they are called telangiectasias) and in the lungs, brain, or liver (where they are called arteriovenous malformations (AVMs)). The location, size and number of these abnormal vessels are different in each person with HHT, even within the same family. Some people with undiagnosed lung or brain AVMs will have serious medical complications, while others remain symptom-free. And many medical problems associated with HHT can be caused by other illnesses. All of these factors make it difficult to know if you or your family has HHT.
When to Get Tested for HHT? A variety of symptoms and medical complications result from HHT. Nosebleeds (caused by bleeding from telangiectasias in the nose) are the most common symptom of HHT, affecting about 95% of people with HHT by the time they reach middle age. Anemia can result from telangiectasias bleeding in the gut (or from frequent nosebleeds). Anemia causes fatigue, shortness of breath and weakness. Multiple small red spots (telangiectasias) on the lips, tongue, fingertips or face, while not harmful, are important in diagnosing HHT. Heart failure can result from AVMs in the liver, though this is uncommon. Stroke, brain abscess (infection) and lung or brain hemorrhage (bleeding)—most of the serious complications in HHT—come from AVMs in the lungs and brain that have not been diagnosed or treated.
HHT should be suspected if a pattern of these symptoms and complications exists in one person or in multiple family members. If you have frequent nosebleeds and you had a stroke or brain abscess with no known cause, then you might have HHT. If you have nosebleeds and your father has many red spots on his face and lips, then you and your family might have HHT. Nosebleeds alone may be a reason to suspect HHT, especially if they are frequent, persist into adulthood and/or are present in multiple generations of your family.
The best way to get tested for HHT is to visit one of the many HHT Centers of Excellence in the US, Canada and other countries (a list of Centers can be found in Living with HHT or at www.curehht.org). The diagnosis of HHT is made by a physician using established criteria including symptoms, family history, and screening tests, or by genetic testing.
What happens after I’m tested? If you’ve been diagnosed with HHT, there are two essential steps you should take: 1) get screening tests to find out whether you have AVMs in your lungs or brain. Strokes, brain abscesses and brain hemorrhages due to lung and brain AVMs are almost all preventable—but only if the AVMs are discovered and treated. 2) Tell your parents, siblings and children that they are also at risk for HHT. They should be tested, either with genetic testing or by clinical examination and screening for AVMs in the lungs and brain. If it turns out you don’t have HHT, then you cannot pass it on to your children; but if your family has the symptom pattern described above, then one of your parents and one or more of your siblings could have HHT, and they need to be tested.
When you know you have HHT, you can get the tests and treatments you need to stay healthy, learn to manage your symptoms and prevent many serious complications. Most people with HHT can live full lives, and researchers are developing new treatments for those who are limited by HHT related illness and disability. So if you think you have HHT, get tested, get screened and get treated! Tell your family and encourage them to do the same.
Want to know more about HHT? In Living with HHT, you will find in-depth discussions of symptoms, diagnosis and screening tests; treatments, procedures and preventive measures; research advances; and how to cope with the emotional and social stress of having HHT. Stay tuned for a future blog post on treatment options. And for more information, visit www.curehht.org .
Sara Palmer, PhD, is a psychologist and an assistant professor in the Department of Physical Medicine and Rehabilitation at Johns Hopkins University School of Medicine. She is the coauthor of Spinal Cord Injury: A Guide for Living; When Your Spouse Has a Stroke: Caring for Your Partner, Yourself, and Your Relationship; and Just One of the Kids: Raising a Resilient Family When One of Your Children Has a Physical Disability. Her latest book, Living with HHT: Understanding and Managing Your Hereditary Hemorrhagic Telangiectasia, deals with managing this little known disease.