What is HTAD?
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- What is HTAD?
What is Heritable Thoracic Aortic Disease?
Heritable Thoracic Aortic Disease (HTAD) refers to a group of genetic conditions that affect the thoracic aorta, the large artery that carries blood from the heart to the rest of the body. The thoracic aorta includes the aortic root, ascending aorta, and aortic arch. In people with HTAD, the aortic wall is more vulnerable to weakening over time, increasing the risk of abnormal enlargement (aneurysm) or tearing (dissection).
HTAD is caused by changes in genes that play an important role in maintaining the structure and function of the aortic wall. These genes influence how connective tissue is formed, how smooth muscle cells behave, and how biological signaling pathways regulate growth and repair. When one of these genes does not function normally, the aorta may gradually enlarge or become fragile, often without causing symptoms until a serious complication occurs.
HTAD is considered a lifelong condition. Many people feel entirely well for years, and the disease may only be discovered during imaging for another reason or after a family member is diagnosed. Because the condition can be silent, early identification is important so that individuals can be monitored over time and treated before complications develop.
Some forms of HTAD are syndromic, meaning they are associated with features outside the heart and blood vessels. Examples include Marfan syndrome, Loeys–Dietz syndrome, and vascular Ehlers–Danlos syndrome, which may involve the eyes, skeleton, skin, or other organs. Other forms are non-syndromic, where the main or only feature is disease of the thoracic aorta.
Most forms of HTAD are inherited in an autosomal dominant pattern. This means that a person with HTAD has a 50% chance of passing the genetic change to each child. Importantly, the severity of disease can vary widely, even among members of the same family. Some individuals may develop significant aortic disease at a young age, while others may have mild or slowly progressive changes later in life.