TABLE V.

Proposed Paradigm for Assessing the Genetic Contribution to Thoracic Aortic Disease

Major genetic contribution (labeled HTAD)	Individuals with identifiable pathogenic variants in a gene causing thoracic aortic disease or individuals with relatives with thoracic aortic disease or with early-onset disease (age, <55 y) who do not have an identifiable variation in a known HTAD gene.
Intermediate genetic contribution	Individuals without an identifiable gene variation or family history who present at a relatively young age (<55 y) and have other environmental or lifestyle risk factors. In these patients, thoracic aortic disease is likely the result of a combination of lower-penetrance genetic variants and risk factors such as hypertension.
Minor genetic contribution	Individuals with relatively late-onset disease (age, >60 y) and no identifiable variation or family history. In these patients, thoracic aortic disease is primarily driven by risk factors such as hypertension or smoking.

HTAD, heritable thoracic aortic disease.