The biological features in the developed AAAs revealed the following: (1) formation of a true aneurysm located infra-renally and fusiform in shape, (2) loss of SMCs and increased degradation of elastin, (3) up-regulated expression and activity of MMP-2 and MMP-9, (4) increased presence of activated macrophages, and (5) the presence of an ILT. This evidence concerns the gene MMP2 and aneurysm.