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Thoracic Aortic Aneurysms and Aortic Dissections.


GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016.
2003 Feb 13 [updated 2012 Jan 12].



The major cardiovascular manifestations of thoracic aortic aneurysms and aortic dissections (TAAD) include: (1) dilatation of the ascending thoracic aorta at the level of the sinuses of Valsalva or ascending aorta or both; and (2) dissections of the thoracic aorta involving either the ascending (Stanford type A dissections) or descending aorta (Stanford type B). Rarely an aneurysm involving the descending thoracic aorta is observed. Vascular manifestations can be the only findings. In the absence of surgical repair of the ascending aorta, affected individuals typically have progressive enlargement of the ascending aorta leading to an acute aortic dissection. The age of onset and presentation of the aortic disease are highly variable, as are the other vascular diseases and features associated with the aortic disease.


TAAD is diagnosed using different imaging modalities such as echocardiography, computed tomography (CT), magnetic resonance imaging (MRI), or angiography. Up to 20% of individuals with TAAD have a first-degree relative with thoracic aortic disease. Familial TAAD (FTAAD) is diagnosed based on the presence of dilatation and/or dissection of the thoracic aorta, absence of clinical features of Marfan syndrome, Loeys-Dietz syndrome, or vascular Ehlers-Danlos syndrome, and presence of a positive family history of TAAD. TGFBR2, TGFBR1, MYH11, ACTA2, MYLK, SMAD3, and two loci on other chromosomes, AAT1 (FAA1) and AAT2 (TAAD1), are associated with familial TAAD. Rarely, FTAAD can also be caused by FBN1 mutations. Further locus heterogeneity is evident: to date, only about 20% of familial TAAD is accounted for by mutations in known genes.


Treatment of manifestations: Medications that reduce hemodynamic stress on the aorta, such as beta adrenergic blocking agents, are recommended. When the rate of dilation of the ascending aorta approaches 0.5 cm per year or the diameter is between 4.2 and 5.0 cm (depending on the underlying mutation or family history), elective repair of the ascending aorta is recommended to prevent a life-threatening aortic dissection or rupture. Early prophylactic repair should be considered in individuals with confirmed mutations in TGFBR2 and TGFBR1 and/or a family history of aortic dissection with minimal aortic enlargement. Surveillance: Appropriate imaging studies (echocardiography, CT, or MRI) should be performed at frequent intervals to monitor the status of the affected segment of the thoracic aorta. Imaging for additional vascular diseases is based on the gene that is mutated and/or family history. Agents/circumstances to avoid: Uncontrolled hypertension, smoking, isometric exercise, bodybuilding/weight training exercises, and competitive sports that could lead to a significant blow to the chest should be avoided. Evaluation of relatives at risk: Aortic imaging is recommended for first-degree relatives of individuals with TAAD. Because of the variability of age of onset of TAAD, aortic imaging once a year or every few years is warranted for at-risk relatives in families with inherited or familial TAAD. If the disease-causing mutation is known, genetic counseling and testing of at-risk first-degree relatives assures that only relatives with the familial mutation undergo aortic imaging.


Familial TAAD is primarily inherited in an autosomal dominant manner with variable expression and decreased penetrance. The majority of individuals with familial TAAD have an affected parent. The children of an affected parent have an up to 50% chance of inheriting the genetic predisposition to TAAD. Prenatal testing for pregnancies at increased risk is possible if the disease-causing mutation in the family is known.

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