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Study Links Heredity and AAA Risk in Twins

by A.F. Hutchinson, Copywriter | February 02, 2010
Identical twins
share AAA risk
While the exact causes of abdominal aortic aneurysms (AAA) are unknown, scientists have long demonstrated genetic links to the condition. For example, a study published in the November 2005 edition of the Journal of Vascular Surgery, which examined the lifetime prevalence of the condition among siblings of aneurysm patients, found that approximately 15% of patients with AAA and without any recognizable connective tissue disorders demonstrated a positive family history for AAA.

Now, results of the largest AAA population-based twin study to date have found that identical twins may be at greater risk for AAA than fraternal twins.

The study, published in the January 2010 edition of the Journal of Vascular Surgery, analyzed the role of hereditary factors in a large population-based sample of twins, using data from the Swedish Twin Registry. Of 172,890 twins born in Sweden since 1886, researchers identified 265 twins with AAAs ranging from 48-98 years of age. A full 81% of the subjects in the Swedish twin study were male. While these findings appear to align with numerous other studies showing that AAAs are more common in males than females, the researchers couldn't make any conclusions about the role of gender in higher hereditary risk among twins. (The study included a single pair of female twins with AAA.)

According to Carl-Magnus Wahlgren, M.D., Ph.D. of the department of vascular surgery at Stockholm's Karolinska University Hospital, seven sets of identical twins and five sets of fraternal twins were examined for probandwise concordance, which is a measure of the proportion of twins with the condition who have an affected twin.

Speaking to the Journal of Vascular Surgery, Wahlgren stated that "the identical pairs had a 24 percent probability that an identical twin of a person with AAA would get the disease. Their risk was 71 times higher than that of the identical twin of a person without AAA."

The study results support ultrasound screening of siblings who have yet to present with an AAA, and underscores the importance of evaluating family history in determining disease prevalence.