Hereditary haemorrhagic telangiectasia (HHT)

Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a genetic disorder that affects blood vessels, leading to abnormal vessel formation and frequent bleeding episodes. It is characterized by the development of telangiectasias (small, widened blood vessels) and arteriovenous malformations (AVMs) in various organs.

Symptoms

Symptoms of HHT can vary widely among individuals and often worsen with age:

• Nosebleeds (Epistaxis): Frequent and severe, starting in childhood.
• Telangiectasias: Small red or purple spots on the skin and mucous membranes, commonly on the face, lips, mouth, and fingers.
• Gastrointestinal Bleeding: Leading to anemia; can cause black or bloody stools.
• Arteriovenous Malformations (AVMs): Abnormal connections between arteries and veins, which can occur in the lungs, brain, liver, and other organs.
• Anemia: Due to chronic blood loss.

Causes

HHT is an autosomal dominant genetic disorder, meaning a single copy of the mutated gene can cause the disease. The condition is typically caused by mutations in one of several genes:

• ENG (Endoglin): Associated with HHT type 1.
• ACVRL1 (ALK1): Associated with HHT type 2.
• SMAD4: Rarely associated with a combined syndrome of HHT and juvenile polyposis.

Types

HHT is classified into several types based on the genetic mutation:

• HHT1: Caused by mutations in the ENG gene.
• HHT2: Caused by mutations in the ACVRL1 gene.
• HHT with juvenile polyposis: Caused by mutations in the SMAD4 gene.

Risk Factors

The primary risk factor for HHT is having a family history of the disorder. Since it is inherited in an autosomal dominant manner, there is a 50% chance of passing the condition to offspring.

Diagnosis

Diagnosing HHT involves a combination of clinical criteria and genetic testing:

1. Clinical Criteria (Curaçao Criteria):
   • Epistaxis: Recurrent nosebleeds.
   • Telangiectasias: Multiple sites on the skin and mucous membranes.
   • AVMs: In the lungs, liver, brain, or gastrointestinal tract.
   • Family history: First-degree relative with HHT.
2. Genetic Testing: Identifies mutations in the ENG, ACVRL1, or SMAD4 genes.
3. Imaging Tests: MRI, CT scans, or ultrasound to detect AVMs in various organs.

Treatments and Medications

While there is no cure for HHT, treatment focuses on managing symptoms and preventing complications:

• Nosebleed Management:
  • Humidification and nasal lubricants.
  • Laser therapy or electrocautery.
  • Nasal packing or topical hemostatic agents.
  • Systemic therapies such as tranexamic acid.
• AVMs Management:
  • Pulmonary AVMs: Embolization or surgery to prevent complications like stroke or brain abscess.
  • Cerebral AVMs: Monitoring, surgical removal, or radiosurgery.
  • Hepatic AVMs: Monitoring and managing complications; liver transplantation in severe cases.
• Anemia Treatment:
  • Iron supplements.
  • Blood transfusions.
  • Endoscopic treatment of gastrointestinal bleeding.

Natural Remedies

Some natural remedies and lifestyle changes may help manage symptoms:

• Humidification: Using a humidifier to keep nasal passages moist.
• Nasal Saline Rinses: To reduce nasal irritation and bleeding.
• Diet: Iron-rich foods to help manage anemia.

Complications

HHT can lead to various complications if not properly managed:

• Severe Anemia: From chronic blood loss.
• Stroke or Brain Abscess: Due to untreated pulmonary AVMs.
• Heart Failure: From high-output heart failure due to liver AVMs.
• Severe Bleeding: From gastrointestinal AVMs or frequent nosebleeds.

Supportive Care

Supportive care for HHT includes:

• Regular Monitoring: For AVMs and potential complications.
• Psychological Support: Counseling for patients and families.
• Patient Education: About managing symptoms and preventing complications.

When to See a Doctor

Individuals with HHT should seek medical attention if they experience:

• Severe or recurrent nosebleeds.
• Signs of anemia (e.g., fatigue, pallor).
• Neurological symptoms (e.g., headaches, seizures, sudden weakness).
• Gastrointestinal bleeding (e.g., black or bloody stools).
• Respiratory symptoms (e.g., shortness of breath, chest pain).

Coping and Support

Coping with HHT can be challenging, but these strategies may help:

• Support Groups: Connecting with others who have HHT.
• Counseling: Professional help for emotional and psychological support.
• Education: Learning about the disease to better manage it.

Caring for the Caregiver

Caregivers also need support to manage their responsibilities effectively:

• Education: Understanding HHT to provide proper care.
• Respite Care: Taking breaks to rest and recharge.
• Support Networks: Seeking help from family, friends, or support groups.

Conclusion

Hereditary Hemorrhagic Telangiectasia (HHT) is a complex genetic disorder with significant implications for affected individuals. Early diagnosis, vigilant monitoring, and appropriate management of symptoms and complications are crucial for improving quality of life. With advancements in genetic testing and treatment, individuals with HHT can manage their condition more effectively and lead fulfilling lives.