What is hereditary hemorrhagic telangiectasia (HHT)?

Did you know that a simple, everyday nosebleed can sometimes be the tip of an iceberg? If you've ever wondered why some people seem to bleed from nowhere, chances are you've stumbled across hereditary hemorrhagic telangiectasia, a genetic bleeding disorder that quietly reshapes tiny blood vessels throughout the body.

In a nutshell, HHT is an inherited condition that creates fragile webs of vesselscalled telangiectasias and arteriovenous malformations (AVMs)in the nose, skin, lungs, brain, liver, and even the gastrointestinal tract. Those delicate vessels are prone to leaking, which means you might notice frequent nosebleeds, red spots on your face, or more serious internal bleeding. Let's dive in together, unpack the science, and figure out what you can actually do about it.

Quick Look Summary

Think of this as your "cheat sheet" before we get into the details.

• What is it? A rare autosomaldominant genetic bleeding disorder.
• How common? Roughly 1 in 5,000 people worldwide.
• Biggest red flag? Recurrent nasal bleeding (epistaxis) that won't quit.
• Why care? Untreated AVMs can lead to serious complications like stroke, brain bleed, or heart failure.

Organ	Typical Sign	RedFlag Warning
Nose	Frequent nosebleeds	Bleeding >2times/week or needing transfusion
Lungs	Shortness of breath, clubbing	Pulmonary AVM paradoxical stroke
Brain	Headache, seizure	Cerebral AVM rupture
GI Tract	Dark stools, irondeficiency anemia	Chronic hidden bleeding
Liver	Tachycardia, highoutput heart failure	Hepatic AVM causing cardiac overload

How HHT Happens

AutosomalDominant Inheritance

HHT runs in families like a family recipeif one parent carries the gene, there's a 50% chance each child will inherit it. The most common culprits are mutations in the ENG gene (HHT1) and the ACVRL1 gene (HHT2). A handful of newer genes, like GDF2 and EPHB4, are also being explored in research labs.

What "Telangiectasia" Really Means

Picture a garden hose that's been kinked and patched with a thin strip of tape. The water still flows, but it leaks out at the weak spots. That's essentially what a telangiectasia is: a tiny, dilated capillary that can't hold pressure and starts to bleed. It's different from harmless "spider veins" you might see on a teenage teenager's legthose don't usually cause bleeding.

Visual Aid Suggestion

If you were sketching this for a friend, you'd draw a normal capillarya neat, tight tubenext to a telangiectasia, which looks like a squiggly, ballooned-out vessel. That contrast makes the concept click instantly.

Why Vessels Become Fragile

Both ENG and ACVRL1 are part of the BMP9/10 signaling pathway, a molecular "traffic controller" for bloodvessel growth. When the pathway falters, endothelial cells (the lining of vessels) proliferate abnormally, leading to weak, leaky connections. A review in the Journal of Vascular Biology breaks down this mechanism in plain language, making it easier to grasp even if you're not a scientist.

HHT Symptoms

Nosebleeds (Epistaxis)

Think of a faucet that keeps dripping no matter how tightly you turn it. For many with HHT, the nose becomes that faucet. Episodes can be triggered by dry air, hormonal shifts, or even a simple sneeze. According to the Mayo Clinic, up to 95% of HHT patients experience recurrent nosebleeds, often daily by the time they're adults.

Skin & Mucosal Telangiectasias

Small, bright red dots may appear on the lips, tongue, fingertips, or even inside the mouth. They're usually painless, but they're a visual cue that the body's vascular network is behaving differently.

Pulmonary AVMs

These are abnormal connections between arteries and veins in the lungs, bypassing the tiny capillaries that normally filter out microemboli. The result? Shortness of breath, clubbing of the fingers, and a sneaky risk of stroke if a clot slips through. It's why routine screening with contrastenhanced CT or a bubble echocardiogram is a lifesaver for many.

Cerebral AVMs

In the brain, an AVM can be a silent troublemakermany people never notice it until a headache, seizure, or rare bleed occurs. Early detection via MRI is key because treatment (often endovascular embolization) can prevent catastrophic outcomes.

Gastrointestinal & Hepatic Involvement

Bleeding from the stomach or intestines may manifest as black, tarry stools and irondeficiency anemia. Meanwhile, hepatic AVMs can create highoutput cardiac failure, a condition where the heart works overtime but still can't keep up.

Diagnosing HHT

Curaao Criteria

Doctors use a set of four clinical cluesrecurrent nosebleeds, telangiectasias, visceral AVMs, and a family history. If you meet three or more, the diagnosis is definitive; two gives you a "possible" label. It's a simple, yet surprisingly accurate tool that originated at Johns Hopkins and Mayo Clinic.

Imaging & Screening Tools

• Chest CT or MRI: Detects pulmonary AVMs.
• Brain MRI: Looks for cerebral AVMs, even tiny ones.
• Contrastenhanced echocardiography: A quick, noninvasive screen for lung shunts.
• Endoscopy: Finds GI telangiectasias.
• Doppler Ultrasound: Screens the liver for AVMs.

Genetic Testing

When the clinical picture is ambiguous, a blood test can identify mutations in ENG, ACVRL1, or other related genes. Remember, a negative result doesn't always rule out HHTsome families carry rare or undiscovered mutations. Reputable labs like CureHHT specialize in these panels.

Experience Tip

Jenna, a 28yearold graphic designer, thought her "just bad" nosebleeds were a teenage phase. After a week-long bleed that left her lightheaded, a simple ENT visit and a family questionnaire revealed she met the Curaao criteria. A genetic test later confirmed HHT2, and she now follows an annual screening schedule that has kept her complications at bay.

Managing & Treating HHT

Controlling Nasal Bleeding

Firstline tricks include humidifiers, saline sprays, and avoiding NSAIDs. For stubborn cases, topical tranexamic acid or laser coagulation can seal the offending vessels. In extreme scenarios, surgeons might perform a "Young's procedure," which reduces blood flow to the nasal mucosa. A JAMA study showed intranasal therapy cut bleeding episodes by 70% in a small cohort.

Embolization of AVMs

Interventional radiologists thread a tiny catheter to the AVM and release coils or glue, effectively "plugging the leak." Pulmonary and cerebral AVM embolization boast success rates above 90% for preventing stroke or bleed. Trerotola & Pyeritz (AJR, 2010) highlighted longterm durability of these procedures.

Pharmacologic Options

• Bevacizumab (antiVEGF): Shows promise for severe anemia and hepatic AVMs by curbing abnormal vessel growth.
• Thalidomide or Pomalidomide: Lowdose regimens can reduce nosebleed frequency, though sideeffects require close monitoring.

Iron Replacement & Anemia Management

Oral iron works for mild cases, but many HHT patients need IV iron or periodic transfusions to keep hemoglobin stable. Always coordinate with a hematologist who understands the chronic bleeding context.

Surgical & Transplant Considerations

When hepatic AVMs cause refractory heart failure, liver transplantation becomes a viable, albeit complex, option. A 2019 case series from the University of Michigan reported a 5year survival of 80% posttransplant for HHTrelated liver disease.

DecisionTree Graphic Suggestion

If you were to draw a flowchart, it would start with "Symptom Imaging Treatment Path." For nosebleeds, the path might lead to "Topical therapy Laser Embolization if refractory." For pulmonary AVMs, the route would be "CT Embolization Followup CT." Such visuals make the journey less intimidating.

Special Populations

• Pregnancy: Hormonal changes can exacerbate AVMs. Experts recommend a prepregnancy screening and close monitoring throughout gestation.
• Children: Telangiectasias can appear early; a pediatric screening protocol (annual ENT exam, biennial MRI brain) is advised by the International HHT Guidelines (2022).

Living with HHT

Lifestyle Adjustments

Simple habits can make a huge difference: keep indoor humidity above 40%, avoid aspirin unless prescribed, and schedule regular ENT visits. Think of it as "maintenance for your vessels."

Monitoring & FollowUp Schedule

Typical recommendations (per Mayo Clinic) include:

• Annual brain MRI
• Chest CT or contrast echo every 23years
• GI endoscopy every 35years if you have anemia
• Routine blood counts to track iron levels

Support Networks

Never underestimate the power of community. Organizations like CureHHT host patient registries, webinars, and local meetups. Connecting with others who "get it" can turn isolation into empowerment.

When to Seek Emergency Care

If you experience massive nosebleeds that don't stop after 20minutes, sudden neurological changes (weakness, confusion), or unexplained shortness of breath, call 911 or head to the ER. Those scenarios signal a possible AVM rupture or severe bleed.

Key Takeaways

Hereditary hemorrhagic telangiectasia is more than an occasional nosebleedit's a lifelong genetic bleeding disorder that reshapes the vascular landscape of multiple organs. Early recognition using the Curaao criteria, diligent screening (CT, MRI, echo), and a multidisciplinary treatment plan (laser, embolization, medication, iron therapy) can keep complications at bay. While there's no cure yet, modern therapies give many people a normal, active life.

If you've spotted any of the signs discussed, don't wait. Talk to your primary care doctor, ask for a referral to a genetics or HHT center, and start building a support network. You're not alone in thisthere's a community ready to help you navigate every bleed, scan, and treatment decision.

What experiences have you had with HHT, or what questions are lingering in your mind? Share your story in the comments, or reach out if you need a friendly ear. Together we'll turn confusion into confidence.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.