An abdominal aortic aneurysm (AAA) is a bulging of the aorta, the body’s main blood vessel, which runs from the heart down through the chest and stomach. Prevalence of AAA in the population is high, up to nearly 13% depending on age group, particularly for men aged 65 and over. An AAA can get bigger over time and rupture, causing life-threatening bleeding. There is a high mortality rate of around 80% in patients with ruptured AAA; only dropping to around 50% when patients undergo surgery.
While clinicians can monitor the beginnings of AAA, a rupture can occur suddenly without warning. Currently, the only available intervention involves a high-risk surgical procedure, which is only undertaken if there is a real danger of rupture. There are no pharmacological treatment options because the underlying causes of AAA are not fully understood.
Scientists know that in some patients there is a genetic predisposition to AAA, and large genomic studies have identified that mutations in a large protein called LRP1 predispose people to aortic aneurysm, as well as other major vascular diseases. However, the mechanism responsible for how these mutated genes cause the disease has so far been unknown. A new paper from DPAG's Smart Group has for the first time demonstrated that a smaller protein called Thymosin β4 (Tβ4) interacts with LRP1 and is ultimately responsible for the behaviour of the smooth muscle cells of the aorta.