This study provides further evidence for familial aggregation and heritability of infrarenal aortic diameter and pathologies of the infrarenal aorta, which reinforces the advice for screening of siblings, and especially twins, of individuals with an abnormal aortic diameter including subaneurysms.
Infrarenal aortic diameter (IAD) correlated more strongly in twins than full siblings and weakest among half siblings.
If a sibling's IAD was 30 mm or greater, the estimated probability of IAD ≥25 mm differed substantially by degree of relatedness.
Heritability estimates were substantial for infrarenal aortic diameter and related pathologies.
The prevalence of AAA, subaneurysmal aorta (SAA), and small aorta among screened 65-year-old men was low but notable.
The study linked a large population-based AAA screening cohort to the Swedish Multigeneration Registry to identify sibling pairs.
This research suggests that the size of the main abdominal artery — the aorta — runs in families. Researchers in Stockholm studied over 107,000 men who underwent ultrasound screening for abdominal aortic aneurysms (AAA), a dangerous condition where the aorta bulges and can rupture. By linking this screening data to a national family registry, they identified nearly 9,000 sibling pairs and found that brothers of men with an enlarged or abnormally small aorta were themselves more likely to have similar aortic abnormalities, and this risk was highest for twins. Specifically, if a man's aorta measured 30 mm or more (meeting the threshold for an AAA), the chance that his twin also had an enlarged or near-enlarged aorta was around 21%, compared to about 5% for a full brother and 2.7% for a half-brother. The study also calculated that roughly 41–61% of the variation in aortic size across individuals can be attributed to genetic factors, with the genetic contribution being even higher for the specific conditions of aneurysmal and small aorta. This research suggests that family history is a meaningful risk factor not just for AAA but also for smaller pre-aneurysmal enlargements and abnormally narrow aortas. The findings support the idea that brothers — and especially twins — of men diagnosed with aortic abnormalities should be offered screening, even when their sibling's aorta is only mildly enlarged (in the subaneurysmal range of 25–29 mm), as genetics appears to play a major role in aortic size across the full spectrum.
Siika A, Hultgren R, Brinck J, Andersson D. (2026). Association of infrarenal aortic diameter in siblings within the Stockholm abdominal aortic aneurysm screening programme.. The British journal of surgery. https://doi.org/10.1093/bjs/znag108