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familial thoracic aortic aneurysms

Monday 13 November 2006

Aneurysms and dissections of the aorta usually result from degenerative changes in the aortic wall.

Thoracic aortic aneurysms and dissections are primarily associated with a characteristic histologic appearance known as ’medial necrosis’ or ’Erdheim cystic medial necrosis’ in which there is degeneration and fragmentation of elastic fibers, loss of smooth muscle cells, and an accumulation of basophilic ground substance.

In contrast, degeneration leading to abdominal aortic aneurysm (100070) is usually caused by a combination of factors including age, atherosclerosis, hypertension, and infectious, inflammatory, or autoimmune processes.

Medial necrosis and thoracic aortic aneurysm/dissection are known to occur in certain connective tissue diseases such as Marfan syndrome (MIM.154700), and vascular (type IV) Ehlers-Danlos syndrome (MIM.130050).

More commonly, however, medial necrosis occurs in the absence of a clearly identifiable syndrome.

Loci for isolated thoracic aortic aneurysm 5AATs) have been identified on chromosomes 11q (AAT1) and 5q (AAT2; MIM.607087).

Mutation in the MYH11 gene (MIM.160745) on 16p causes AAT4 (MIM.132900) . Mutation in the ACTA2 gene (MIMI.102620) on 10q causes AAT6 (MIMI.611788) . Thoracic aortic aneurysm with dissection can occur as a manifestation of the Loeys-Dietz syndrome (MIM.610380 and MIM.608967).

Synopsis

- predominant inheritance pattern: autosomal dominant (76.9%)

Loci

- AAT1 (MIM.607086)
- AAT2 (MIM.607087)
- AAT3 (LDS2B - MIM.6010380)
- AAT4 (MIM.132900): MYH11 (MIM.160745)
- AAT5 (LDS2AA - MIM.608967)
- AAT6 (MIMI.611788): ACTA2 (MIMI.102620)

See also

- sporadic TAA
- Marfan syndrome (MFS)
- familial clustering
- penetrance
- expressivity

References

- Albornoz G, Coady MA, Roberts M, Davies RR, Tranquilli M, Rizzo JA, Elefteriades JA. Familial thoracic aortic aneurysms and dissections—incidence, modes of inheritance, and phenotypic patterns. Ann Thorac Surg. 2006 Oct;82(4):1400-5. PMID: 16996941