Hemorrhagic Telangiectasia, Hereditary (HHT): A Guide to Symptoms and Treatment

Hemorrhagic Telangiectasia, Hereditary (HHT)

Introduction

Hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome, is a rare genetic condition that causes abnormal blood vessels to develop in various parts of the body. These blood vessels are weak and fragile, making them prone to bleeding.

HHT is characterized by three main types of abnormal blood vessels:

• Telangiectasias: Tiny, red or purple spots on the skin or mucous membranes
• Arteriovenous malformations (AVMs): Abnormal connections between arteries and veins
• Epistaxis: Frequent nosebleeds

Causes

HHT is caused by mutations in the following genes:

• ENG: Encodes a protein called endoglin, which plays a role in blood vessel formation
• ACVRL1: Encodes a protein called activin A receptor-like type 1, which is also involved in blood vessel development

These mutations lead to the abnormal formation of blood vessels, which are weak and have difficulty regulating blood flow.

Inheritance

HHT is an autosomal dominant condition, meaning that only one copy of the mutated gene is needed to cause the disease. Each affected individual has a 50% chance of passing on the mutated gene to their children.

Symptoms

The symptoms of HHT can vary depending on the severity and location of the abnormal blood vessels. Common symptoms include:

• Nosebleeds: Frequent, heavy, or prolonged nosebleeds that can be difficult to control
• Skin telangiectasias: Small, red or purple spots on the skin, often around the lips, nose, or fingers
• Mucous membrane telangiectasias: Tiny, red or purple spots on the mucous membranes of the mouth, nose, or digestive tract
• Arteriovenous malformations (AVMs): Abnormal connections between arteries and veins, which can occur in the lungs, brain, liver, or other organs
• Gastrointestinal bleeding: Bleeding from the stomach or intestines, which can cause anemia and fatigue
• Central nervous system complications: AVMs in the brain can cause headaches, seizures, or strokes
• Cardiovascular complications: AVMs in the lungs or liver can lead to heart failure or other cardiovascular problems

Diagnosis

HHT is diagnosed based on the patient’s symptoms and a physical examination. The doctor may also order the following tests:

• Endoscopy: A procedure to examine the lining of the stomach and intestines for telangiectasias or AVMs
• Angiography: An imaging test that uses dye to visualize the blood vessels and detect AVMs
• Genetic testing: To confirm the diagnosis and identify the specific gene mutation responsible for the condition

Treatment

There is no cure for HHT, but treatment can help to control the symptoms and prevent complications. Treatment options include:

• Medications: To reduce bleeding and improve blood flow
• Laser therapy: To cauterize telangiectasias and shrink AVMs
• Embolization: A procedure to block off AVMs and prevent bleeding
• Surgery: To remove or repair AVMs in certain cases
• Blood transfusions: To treat anemia caused by gastrointestinal bleeding

Management

In addition to medical treatment, patients with HHT can take the following steps to manage their condition:

• Regular checkups: To monitor their condition and identify any new or worsening symptoms
• Avoid strenuous activity: To minimize the risk of bleeding
• Wear a medical alert bracelet: To inform healthcare providers of their condition in case of an emergency
• Join support groups: To connect with others who are managing HHT and learn about the latest research and treatment options

Prognosis

The prognosis for HHT varies depending on the severity and location of the abnormal blood vessels. With proper management, most people with HHT can lead full and active lives. However, some individuals may experience complications, such as severe bleeding, organ damage, or neurological problems, that can affect their overall health and quality of life.

Research

Researchers are actively studying HHT to better understand the causes, develop new treatments, and improve the prognosis for affected individuals. Current research areas include:

• Gene therapy: To introduce a healthy copy of the mutated gene into affected cells
• Stem cell therapy: To use stem cells to repair or replace damaged blood vessels
• Targeted drug therapy: To develop drugs that specifically inhibit the growth and development of abnormal blood vessels

Conclusion

Hemorrhagic telangiectasia, hereditary (HHT) is a rare genetic condition that causes abnormal blood vessels to develop in various parts of the body. While there is no cure for HHT, treatment options can help to control the symptoms and prevent complications. Regular checkups, lifestyle modifications, and support from healthcare providers and support groups can help individuals with HHT manage their condition and live full and active lives. Ongoing research continues to advance our understanding of HHT and explore new treatment approaches for affected individuals.