What are the other Names for this Condition? (Also known as/Synonyms)

• HHT (Hereditary Hemorrhagic Telangiectasia)
• Osler-Rendu-Weber Disease
• Osler-Weber-Rendu Syndrome

What is Hereditary Hemorrhagic Telangiectasia? (Definition/Background Information)

• Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder involving the blood vessels that can cause excessive bleeding, due to the formation of abnormal blood vessels called arteriovenous malformations (AVMs) in several areas of the body. It is also known as Osler-Weber-Rendu Syndrome
• The AVMs can form anywhere in the body, including in the brain, lungs, liver, or intestines. When it forms on skin, it is termed telangiectasias. These malformations can result in a wide variety of signs and symptoms, such as nosebleeds, blood in urine, internal bleeding, and severe anemia, which can be life-threatening
• Hereditary Hemorrhagic Telangiectasia is typically an incurable disorder, and the treatment provided is symptomatic and supportive, which may include medications and surgery, based on the healthcare provider’s assessment. The outcomes vary from one individual to another, and depends on the severity (extent of involvement of the various body organs)

Who gets Hereditary Hemorrhagic Telangiectasia? (Age and Sex Distribution)

• Hereditary Hemorrhagic Telangiectasia is a rare congenital disorder. The presentation of symptoms may occur following the birth of the child, or much later
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Hereditary Hemorrhagic Telangiectasia? (Predisposing Factors)

• A positive family history may be an important risk factor, since Hereditary Hemorrhagic Telangiectasia is an inherited condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Hereditary Hemorrhagic Telangiectasia? (Etiology)

• Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder that is inherited in an autosomal dominant manner
• An involvement of the following genes have been noted in HHT:
  • ACVRL1 gene
  • ENG gene
  • SMAD4 gene
  • GDF2 gene
• It is researched that there may be other causative genes too, which are as yet unidentified

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition, or pass it on to their offspring.

What are the Signs and Symptoms of Hereditary Hemorrhagic Telangiectasia?

The signs and symptoms of Hereditary Hemorrhagic Telangiectasia may vary widely from one individual to another and may be mild or severe. The signs and symptoms may include:

• Nosebleeds
• Blood in stool
• Headaches
• Skin lesions on the lips, fingers and nose that bleed occasionally
• Red or purple spots; mesh-like appearance of blood vessels on skin
• Shortness of breath
• Iron deficiency anemia
• Fatigue

How is Hereditary Hemorrhagic Telangiectasia Diagnosed?

Hereditary Hemorrhagic Telangiectasia is diagnosed on the basis of the following information:

• Physical examination of the individual and medical history evaluation (including family medical history)
• Assessment of the presenting signs and symptoms
• Blood tests, as needed
• Radiological imaging studies of the affected regions
• Skin biopsy, if necessary: A skin tissue biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis
• Molecular genetic testing to check for or confirm specific causative gene mutation(s)
• Prenatal testing including abdominal ultrasound scans

A differential diagnosis may be necessary to eliminate other conditions that present similar signs and symptoms.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Hereditary Hemorrhagic Telangiectasia?

The complications of Hereditary Hemorrhagic Telangiectasia may include:

• Severe anemia
• Involvement of several vital organs including the brain, intestines, heart, lungs, liver, etc. with severe complications
• Acute and chronic digestive tract bleeding
• Brain abscess
• Ischemic stroke
• Congestive heart failure
• Liver cirrhosis
• Severe bleeding causing life-threatening situations
• Reduced quality of life

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Hereditary Hemorrhagic Telangiectasia Treated?

Hereditary Hemorrhagic Telangiectasia (HHT) is an incurable condition and the treatment of HHT is largely supportive and symptomatic. It is important to immediately address any bleeding episodes and prevent associated medical complications. This may involve:

• Vitamin (iron) supplementation and antifibrinolytics; aggressive iron replacement therapy for severe cases
• Argon plasma coagulation
• Transcatheter embolization
• Controlling nosebleeds through nasal swabs, use of humidifier, or saline solution
• Surgical procedures may include laser ablation, skin grafts, and nasal cautery
• Stereotactic radiotherapy for brain AVMs
• Liver transplantation, if necessary
• Having a balanced diet

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

How can Hereditary Hemorrhagic Telangiectasia be Prevented?

Currently, Hereditary Hemorrhagic Telangiectasia may not be preventable since many of these genetic disorders are diagnosed at or following the birth of the child.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

What is the Prognosis of Hereditary Hemorrhagic Telangiectasia? (Outcomes/Resolutions)

• The prognosis of Hereditary Hemorrhagic Telangiectasia is dependent upon the severity of the signs and symptoms and associated complications. With appropriate and prompt treatment, the outcomes are generally good
• It is reported that about 10% of the individuals succumb to the condition from heart/lung/kidney/liver or central nervous system complications

Additional and Relevant Useful Information for Hereditary Hemorrhagic Telangiectasia:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/