Interestingly, the association of altered collagen I:III ratio, reduced collagen III or increased collagen I levels with sporadic aortic aneurysm formation [71] and the recent important identification of COL3A1 mutations in patients with sporadic thoracic dissection [43], underscores the clinical relevance of collagen III in both genetic and sporadic vascular disease including aortic aneurysms. This evidence concerns the gene COL3A1 and aortic aneurysm.