New belly aortic aneurysm genes recognized, might assist pinpoint these in danger

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New abdominal aortic aneurysm genes identified, could help pinpoint those at risk

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A veteran study identified more than a dozen genes associated with the abdominal aortic aneurysm (AAA) that can be used to better identify individuals at risk for the often fatal disease. This is based on new research published today in the American Heart Association's flagship journal Circulation.

The abdominal aortic aneurysm is a bulging or weakening of the aorta – the largest blood vessel in the body. Only about 20% of patients survive an abdominal aortic aneurysm rupture. Previous studies have identified 10 locations in the human genome that are associated with potential risks. However, these genes are only a fraction of the causes of the disease.

"This study doubled the number of genetic associations with the abdominal aortic aneurysm and greatly expanded our understanding of disease mechanisms," said author Philip S. Tsao, Ph.D., professor of cardiovascular medicine at Stanford University School of Medicine and Director of the VA Palo Alto Epidemiology Research and Information Center for Genomics in California. "This new information can improve screening protocols and help identify individuals at risk for an abdominal aortic aneurysm."

Researchers used the world's largest genetic biobank, the Million Veteran Program, to identify several new genetic factors associated with the abdominal aortic aneurysm and to identify new populations for future therapies. The Million Veteran Program was launched in 2011 to study how genes affect the health of US veterans.

Using the Million Veteran Program database, researchers conducted a genome-wide association study of European descent veterans that tested approximately 18 million DNA sequence variants among more than 7,500 cases of abdominal aortic aneurysms and 172,000 veterans without abdominal aortic aneurysms.

They then examined the effects of blood pressure on abdominal aortic aneurysms using Mendelian randomization – a technique that uses genetic variation to examine the causal relationship between traits. They also looked at whether risk factors for abdominal aortic aneurysms were related to aneurysms in other areas of the body.

During the tests, researchers created a "polygenic risk score" to identify subgroups of the population who are more likely to develop abdominal aortic aneurysms.

The analysis showed:

  • 14 previously unidentified genetic sites associated with the development of an abdominal aortic aneurysm – bringing the total number of known genetic associations to 24.
  • A genetic increase in diastolic blood pressure of 10 mm Hg – the lowest number on a blood pressure reading – increased the risk of developing an abdominal aortic aneurysm.
  • Nineteen of the 24 risk variants for abdominal aortic aneurysm were associated with aneurysms in other parts of the body.
  • The polygenic risk score was strongly associated with abdominal aortic aneurysm regardless of known risk factors including smoking and family history.

"We were surprised that diastolic blood pressure, as opposed to systolic blood pressure, is likely to be more important in the development of an abdominal aortic aneurysm," said Tsao.

The researchers replicated the results in an independent set of nearly 5,000 cases of abdominal aortic aneurysms and 100,000 controls (people without abdominal aortic aneurysms).

Researchers say the study is somewhat limited as the database is mostly European ancestry veterans. With the advancement of genetics, this suggests that more samples are being taken from people of different backgrounds to limit the possibility of ethnic differences in precision medicine.

Genetic assessment can identify more men who are at risk for an aortic aneurysm

Provided by
American Heart Association

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