Dr. Jamie McDonald, certified genetic counselor, says that number may be underrepresented, estimating that nine out of 10 people with HHT go undiagnosed. Dr. McDonald talks about what HHT is, its causes and symptoms, and how clinics like The HHT Center of Excellence can help.">

Tags: u0102103, genetic counseling, genetics, inherited, blood

Jun 1, 2016 — Hereditary Hemorrhagic Telangiectasia (HHT) is an inherited genetic disorder involving abnormalities in the blood vessels. The disorder affects one in 5,000 Americans. Dr. Jamie McDonald, certified genetic counselor, says that number may be underrepresented, estimating that nine out of 10 people with HHT go undiagnosed. Dr. McDonald talks about what HHT is, its causes and symptoms, and how clinics like The HHT Center of Excellence can help.


Interviewer: What are the symptoms of HHT and what should you do about it? We'll talk about that next on The Scope.

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Interviewer: Nine out of 10 people with the genetic disorder HHT are still undiagnosed. What makes it so difficult is it can have multiple and seemingly unrelated symptoms. If not treated properly, it can have dire consequences. Jamie McDonald is a licensed genetic counselor and Co-Director of the HHT Center of Excellence at University Utah Health Care. I'm not going to attempt to say it. I'd like you to say it and maybe I'll try afterward. What does HHT stand for?

Jamie: It stands for hereditary hemorrhagic telangiectasia. Hereditary, of course, means it runs in families. Hemorrhagic means that it is associated with bleeding. And the word "telangiectasia" that indeed, one has to hear about 50 times to be able to say, refers to a very specific type of blood vessel abnormality. It is, in particular, a blood vessel that is abnormal because an artery is directly connected to a vein rather than connected via a capillary network, which is the normal thing.

Interviewer: And different places, different people have it in different places and different quantities of them? Some people might have a few, some people might have a lot?

Jamie: Exactly. That is the case that there is huge variability and surprising to even many physicians that don't see a lot of this disorder, it's variable even within the same family. So it would be reasonable to expect that if a parent had certain manifestations of this disorder or a certain severity of different manifestations, then maybe it would be likely that their child would as well. It's absolutely not the case. It's very variable from person to person, even within the same family.

Interviewer: And it is a genetic issue, as we've established before so it's hereditary. Why are we just now hearing about it?

Jamie: The fact that 1 in 5000 people are affected rather than the frequency with which people have diabetes or congestive heart failure has decreased the chance that people are going to become aware of it.

Interviewer: So it's something that affects even 1 in 5000 doesn't sound like a lot, it can turn out to be quite a few.

Jamie: Absolutely. And those of us that see many HHT families and sort of collect them, if you will, because we focus on this disorder, feel that 1 in 5000 probably is a significant underrepresentation. When I see families and take a three to four generation family history, as I do, all of a sudden, after having asked the right questions about those family members, I have in front of me on my family tree a pedigree of five people in my patient's family that clearly have HHT but haven't been diagnosed because the pieces of the puzzle haven't been put together.

Interviewer: Let's talk about some of those pieces. What are some of the symptoms that people might have? I've heard nosebleeds commonly referred to. Is that one of the main ones?

Jamie: Absolutely. It is the main one. About 95% of people with HHT will have recurring nosebleeds by the time they're adults, say, 40 years of age. But recurring may mean one every two weeks or it may mean two an hour. So it's extremely variable and you can imagine that if somebody has one nosebleed every two weeks that stops in a minute's time, they may not have even reported that to their physician. So it's the cardinal, most common feature, but not the feature we're most worried about.
The features we're most worried about are the larger, abnormal blood vessels we call AVMs or arterial venous malformations, that can occur in the lung and the brain and liver and lay hidden unless you go looking for the because you've been tipped off that they might be there based on the person's history and family history of nosebleeds. And then, the second thing that can actually be seen on the outside of the body, before we start doing fancy imaging tests to look inside the body, are little tiny telangiectasias or what show up as red spots on the hands, mouth, face of the body.

Interviewer: And are those red spots there all the time?

Jamie: They're there all the time. They don't come and go like a rash would, for example. They're there all the time. Although, people tend to develop more of then with age. At birth, a baby that's born with HHT, for example, because, after all, it's hereditary, a baby gets HHT by inheriting it from a mom or dad. So it's there at birth in some fashion or another. But, usually, the telangiectasias on the skin don't show up until adulthood.

So one of our key concerns as we work our way through families where many people aren't diagnosed yet is people will develop an AVM in their brain in this disorder, usually, years before they actually develop the nosebleeds and red spots on the outside. So the underlying features of HHT that we're most concerned about don't jump out at doctors when they see these patients in their clinics.

Interviewer: The symptoms might not show up so what are some of the damages of this?

Jamie: The significant damage is the baby that has a brain bleed or brain hemorrhage from a ruptured AVM at three years of age before they've had a chance to develop the nosebleeds that begin at average age 11, 12 or red spots on the outside on the skin, which develop average age 20s or 30s. The brain bleed can occur in a young child from an AVM in the brain or a 30-year-old can have a stroke or a brain abscess due to a lung AVM. The blood isn't being filtered out of clots each time it circulates the body and passes through the lungs.

If blood goes through an AVM in the lung and the clot isn't filtered out and that blood then goes to the brain, it's a stroke. So strokes, both of hemorrhagic nature and of a clot blocking off a blood vessel nature, are both risk factors for people with HHT that haven't ben appropriately diagnosed and screened.

Interviewer: So what do you do? How do you find out if you have it if you're not showing the symptoms of the nosebleeds? I guess, first of all, if you have fairly consistent nosebleeds, you probably should go do a little bit more research on that and see if you have HHT.

Jamie: Absolutely.

Interviewer: I could have it and not know it, right?

Jamie: Absolutely. The key there is once HHT is identified in a family in someone old enough to have the nosebleeds and the red spots on the skin and/or brain hemorrhage that leads to the diagnosis, to not let the evaluation stop there. When we have a patient come to our clinic and say it's a 50-year-old mother and grandmother, and we make the diagnosis of HHT, there's an evaluation we're going to do for her to make sure she doesn't have one of these hidden time bomb AVMs inside an internal organ. But, from our perspective, the whole family has become our patient. We're going to talk to her about her kids, her grandkids and what they should have in the way of testing.

At this point, thankfully, genetic testing for HHT is available. I can draw a blood sample on that 50-year-old mother/grandmother we just diagnosed with HHT and prove in her down at the genetic level what's causing her HHT, exactly which gene and which mutation in which gene is causing her HHT. Because it's different in each family with this disorder. But once I've pinpointed that in one member of the family, I know that anybody in that family that inherited the HHT will have that exact same mutation. So I can now test her kids and grandkids.

Interviewer: So the key is to think, "Huh, did Uncle Al have regular nosebleeds all the time? He did and he always complained about them. Hmm."

Jamie: Exactly. Exactly.

Interviewer: All right.

Jamie: But again, these are pieces of the puzzle that had to be put together in order to come up with a diagnosis. Often times, it requires looking at the whole family, not jus the individual in front of you.

Interviewer: Most of your patients, do they figure this out on their own or they have a doctor help them?

Jamie: It's a combination. Oftentimes, an astute physician suspects it originally, oftentimes in a member of the gamily that has a particular number of manifestations and then after having had that diagnosis floated to the patient by a primary care doc, the patient gets on the Internet, finds out that there actually are specialty centers and specialty clinics for this rare disorder and makes their way to either us or one of the other specialty centers.

Interviewer: That sounds like if you think you might have it, the next step for most people is to find the specialty center, like here at University of Utah Health Care. If somebody's looking for more information about HHT, do you have a resource that you recommend to somebody?

Jamie: Absolutely. There's a national group called CureHHT, formerly known as the HHT Foundation, that is a resource for patients and physicians alike, including a list of HHT centers of excellence nationally.

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