Abdominal aortic aneurysm (AAA) is a common disorder found in ~5% of all New Zealand men over the age of 60. Over 500 surgical repairs are conducted in New Zealand at a cost of over $10M per annum. It is well known that both inherited (genetic) and environmental factors, such as smoking, contribute to an individual's risk of developing an aneurysm. The objective of this study is to better understand the ways in which genetic and environmental factors interact (epigenetics). To do this, we will examine a large number of DNA modifications (epigenetic markers) in blood cells and compare expression in those with and without AAA. We will also compare epigenetic markers with genetic and demographic risk factors from the same study participants. In so doing, we hope to identify: (1) novel risk prediction markers and (2) possible therapeutic drug targets to help treat this life-threatening disease.