While MMP-7 shows increased expression in AAA and weakens the aortic wall via the promotion of smooth muscle cell apoptosis, the MMP-13 concentration in human aortic tissue was likewise found to be 1.8-fold higher in AAA compared to atherosclerotic aortas and was not expressed in aortic tissue of organ transplant donors [168,169]. This evidence concerns the gene MMP7 and triple-A syndrome.