Importantly, matrix metalloproteinase (MMP) 9 derived from macrophages and MMP2 derived from vascular smooth muscle cells (SMCs) [4]–[6] have been shown to be critical factors required for the elastin destruction and proteolytic degradation that are hallmark features of AAAs, thereby leading to gradual aortic dilatation. This evidence concerns the gene MMP2 and achalasia-alacrima syndrome.