Observed genes

Polygenic score

Influential genes: CDKN2B-AS1,GPHN,SYT1,CSMD1,RARB

The gene CDKN2B has been associated with the development of Abdominal Aortic Aneurysm.

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Overview

The abdominal aorta is the major artery of the lower body, delivering blood to the abdomen, pelvis, and lower limbs. An abdominal aortic aneurysm (also known as AAA) is a disease, in which there is a permanent, irreversible dilatation (bulging out) of the aorta.

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Prevalence and Risk Factors

AAA is most common in males above 65 years of age. The number of affected people rises with age. Screening studies have shown that the prevalence of AAA is between 4% and 8% in the general population.[1] Abdominal aortic aneurysm and its complications are unfortunately also a quite common cause of death in persons >55 years – 12-15th leading cause in the USA,[2] the UK, and multiple European countries, in fact. Nevertheless, age is not the only factor that contributes to the development of an AAA and others can be positively influenced. It has been shown that smoking significantly increases the risk, and therefore smoking cessation effectively reduces the risk of developing an AAA. Other important factors are the presence of the disease in close relatives and other potential cardiovascular diseases of the patient – especially uncontrolled hypertension, which in turn can usually be managed well by your general practitioner and living a healthier lifestyle.

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Genetics

Abdominal aortic aneurysm is associated with genetic diseases of the connective tissue. Twin studies suggest that heritability can be as high as 70%. Furthermore, a positive family history is considered higher the risk of developing the disease by twofold.[7] The inheritance pattern has been the target of research in the last years. The deeper knowledge of the genetic background of abdominal aneurysm would have a major impact on early diagnosis and monitoring. However, further research is needed, as this condition is characterized by heterogeneous mutations.[8] 

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Genetic testing allows us to detect whether you have the predisposition to develop this disease. In Macromo, we use polygenic risk scores and causative evidence-based genetic variants for evaluation. The polygenic risk score (PRS) represents the total number of genetic variants that increase an individual's risk of developing a particular disease. All variants across their genome are summed and ranked according to their effect on disease development.

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Signs and symptoms

Unless ruptured, an abdominal aortic aneurysm usually does not cause any major symptoms. It is often diagnosed as a part of a screening program, or incidentally on a routine physical exam. When an AAA ruptures, however, it is a life-threatening emergency. Larger aneurysms have a greater chance of an eventual rupture (>5,5 cm diameter), as well as causing symptoms prior to the rupture. It should be noted that the risk of rupture of an aneurysm measuring less than 4 cm is estimated to be close to 0 %.[3] AAA can in general present with a pulsating bulge on the abdomen, hypotension and abdominal/flank pain. Sometimes, a blood clot originating from the dilatation may prevent blood flow to a limb, resulting in a pale, painful leg that is cool to the touch.

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Diagnosis

To diagnose a patient with an abdominal aortic aneurysm, imaging technologies are used, based on preliminary findings of a physical examination. The imaging test of choice in asymptomatic AAA is ultrasound, whereas, in symptomatic AAA, computed tomography (CT) scan is preferred. A screening ultrasound test is usually recommended for males above >65 with a history of smoking, as well as for males and females >60 who have a family history of AAA.

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Therapy

There are two methods of repairing an aortic aneurysm – open abdominal, and endovascular, which are similar in long-term outcomes. The choice between these two is made based on the patient’s anatomy, individual risk factors, and personal preference.

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Prevention

As smoking has been associated with an increased risk of AAA, smoking cessation is strongly recommended as a method of prevention. The risk decreases upon smoking cessation gradually over a number of years and ultimately leads to a more than halved risk in comparison to current smokers.[4] Additionally routine screening is recommended for men over the age of 60, although this varies by country. Should an unruptured aneurysm be detected, surgical repair is successful in more than 95 % of the cases.[5]

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Prognosis

Without treatment, a ruptured abdominal aneurysm is almost always fatal. Studies show that only about 50% of people with ruptured AAAs reach the hospital.[6] The goal of the therapy is thus to detect and repair the aneurysm before it ruptures. This is done as an elective surgical procedure, based on the patient’s risk profile. The procedure is recommended by the physician, based on the size of the aneurysm and other factors. 

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Recommendations

• Early ultrasound imaging test is crucial in discovering Abdominal Aortic Aneurysm
• Visit your health practitioner if your genetic predisposition is high
• If you observe a pulsating bulge on your abdomen, along with a strong abdominal/back/flank pain, contact your physician
• Smoking cessation is very important as a preventative measure

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