Mutations in a gene expressed in smooth muscle cells account for about 14% of cases of hereditary thoracic aortic aneurysm, reports a paper published online Nature Genetics. A thoracic aortic aneurysm is a widening of the wall of the aorta -- the body's largest artery -- and can lead to heart attack and stroke.
About one in five of all individuals affected by thoracic aortic aneurysms and dissections (TAAD) have a family history of the disorder, suggesting a genetic predisposition. Only two genes have been implicated in familial cases of TAAD so far, and they account for only about 5% of such cases. Dianna Milewicz and colleagues mapped the gene causing a novel form of TAAD in a large family, and identified mutations in ACTA2, encoding smooth muscle alpha-actin. Mutations in ACTA2 were also identified in individuals in 14 additional families affected by TAAD. Smooth muscle alpha-actin is the most abundant protein found in smooth muscle cells, which are required for contraction of the aorta and other blood vessels in the regulation of blood pressure and flow. One of the other proteins associated with TAAD, MYH11, interacts with ACTA2 in regulating smooth muscle cell contraction, and the authors suggest that this process must be critical in maintaining the structural integrity of the aorta. It is not known whether mutations in ACTA2 are involved in non-familial cases of TAAD.
Dianna Milewicz (University of Texas Health Science Center, Houston, TX, USA)
Abstract available online.
(C) Nature Genetics press release.
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