What is Hereditary Hemorrhagic Telangiectasia

Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare genetic disorder that causes abnormal blood vessel formations known as arteriovenous malformations (AVMs). These fragile vessels can occur anywhere in the body, most commonly leading to chronic nosebleeds, skin spots, and potentially serious internal bleeding in the lungs, brain, or liver.

What exactly is Hereditary Hemorrhagic Telangiectasia?

Hereditary Hemorrhagic Telangiectasia is a systemic vascular disorder characterized by an inability of blood vessels to form properly. In a healthy circulatory system, arteries connect to capillaries, which then transition into veins. In individuals with Hereditary Hemorrhagic Telangiectasia, these capillaries are often missing, causing high-pressure arterial blood to flow directly into veins. These connections, called arteriovenous malformations (AVMs), are structurally weak and prone to rupture, leading to the "hemorrhagic" (bleeding) component of the disease.

Which body systems are affected by Hereditary Hemorrhagic Telangiectasia?

Because blood vessels are present throughout the entire body, Hereditary Hemorrhagic Telangiectasia can impact multiple organ systems. The clinical presentation varies significantly even among family members. Common manifestations include:

• Nose (Epistaxis): Frequent, spontaneous nosebleeds are the most common symptom, affecting over 90% of patients.


• Skin and Mucosa: Small, red, spider-like spots called telangiectasias often appear on the lips, tongue, fingertips, and face.


• Lungs (Pulmonary AVMs): These are critical to monitor as they can allow blood to bypass the lung's filtering system, potentially leading to strokes or brain abscesses.


• Gastrointestinal Tract: Fragile vessels in the stomach or intestines can cause chronic, often hidden, bleeding.


• Liver and Brain: AVMs can occur in the liver or central nervous system, requiring specialized screening and management.

How common is Hereditary Hemorrhagic Telangiectasia?

Hereditary Hemorrhagic Telangiectasia is estimated to affect approximately 1 in 5,000 to 1 in 8,000 people worldwide. It is a pan-ethnic condition, meaning it affects all geographic populations and genders equally. While symptoms can appear in childhood, many individuals are not diagnosed until adulthood when symptoms become more pronounced or complications arise. Currently, our DiseaseMaps.org community includes 141 individuals who are navigating life with this condition, highlighting that while it is rare, you are not alone.

What causes this condition and is it hereditary?

Yes, Hereditary Hemorrhagic Telangiectasia is an autosomal dominant genetic disorder. This means that if one parent has the condition, there is a 50% chance that each child will inherit the genetic mutation. It is primarily caused by mutations in the ENG (HHT1) or ACVRL1 (HHT2) genes, which are responsible for the development and stability of blood vessel walls.

Next steps

• Consult a specialist physician, preferably at an HHT Center of Excellence, for a comprehensive screening.


• Request a referral to a clinical geneticist to discuss genetic testing for you and your family members.


• Join the DiseaseMaps.org community to connect with other patients and share experiences.


• Educate your primary care provider about your diagnosis, especially before any surgeries or dental procedures.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• Orphanet: Hereditary Hemorrhagic Telangiectasia (ORPHA:774)


• NIH Genetic and Rare Diseases Information Center (GARD): HHT


• Cure HHT (HHT Foundation International): Clinical Guidelines and Patient Resources


• OMIM (Online Mendelian Inheritance in Man): Entry #187300