A detailed study of 520 patients with thoracic aortic aneurysm (TAA) and dissection indicates a very strong genetic link, Yale School of Medicine researchers report in the Annals of Thoracic Surgery.

"All immediate family of patients with aneurysms of any type should be screened for TAA and abdominal aortic aneurysms (AAA)," said John Elefteriades, M.D., section chief of cardiothoracic surgery and senior author of the study. He said the Yale Center for Aortic Diease screens siblings, parents, grandparents, children, and grandchildren, as well as more distant relatives, in highly affected families.

Rapid advances are being made in understanding TAA disease at the molecular genetic level and chromosomal loci have been identified that relate to the TAA phenotype by using the methods of linkage analysis and gene sequencing, he said.

"As advances in molecular genetics continue, it remains important to evaluate the clinical patterns of genetic transmission of thoracic aortic aneurysm in large populations," Elefteriades said.

He and his team conducted interviews with 520 patients with TAAs to identify family members with aneurysms. Study patients were divided into three groups: 369 patients with no family pattern (sporadic group); 50 patients with Marfan syndrome, a connective tissue disorder that weakens the walls of major arteries, including the aorta, and 101 non-Marfan patients with a family history of TAA (familial group).

The researchers then determined the incidence of family clustering, age at presentation, rate of aneurysm growth, incidence of hypertension, correlation of aneurysm sites among kindred, and pedigree inheritance patterns.

There was an inherited pattern for TAA in 21.5 percent of non-Marfan patients. Family members of patients with aneurysms also tended to have their aneurysms in the same location of ascending or descending aorta. There was also an age difference. The familial group was significantly younger than the sporadic group, but not as young as the Marfan group. The early age of onset suggests a virulent disease pattern in the familial patients.

"It is quite likely that the true rate of inheritance of TAA is even higher than this study indicates," Elefteriades said. "To be counted as affected in this study, a family member needed to have a known aneurysm. Many may well have harbored an aneurysm but simply not have been diagnosed or aware."

The authors want physicians and patients with aneurysms to be aware of the strong familial tendency of this disease so that relatives can be tested. They point out that testing to uncover silent aneurysms can lead to a saving of lives through pre-emptive surgery to prevent rupture.

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Annals of Thoracic Surgery 82: 1400-06 (October 2006)

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