Functional matrix metalloproteinase-9 polymorphism (C-1562T) associated with abdominal aortic aneurysm. 
Matrix metalloproteinase-9 (MMP-9) is a potent endopeptidase with activity against both collagens and elastin.  Expression of MMP-9 is elevated in vascular disease, and in particular within aneurysm tissues.  This study tested the hypothesis that the functionally more active T allele of the MMP9 C-1562T polymorphism may be overrepresented in patients with abdominal aortic aneurysm (AAA) compared with control subjects and patients with atherosclerotic peripheral vascular disease (PVD).  Seven hundred eighty-nine unrelated persons (AAA, n = 414; control subjects, n = 203; PVD, n = 172) were genotyped for the common C-1562T functional promoter polymorphism of the MMP9 gene.  Genotypes containing the T allele of this polymorphism were significantly more common in patients with AAA compared with both control subjects and patients with PVD (adjusted odds ratio, 2.41 and 2.94, respectively).  The greatest shift between groups was observed in male patients, with a difference of 20.6% in CT/TT genotypes.  and 12.1% in T allele frequency between patients with AAA compared with patients with PVD.  This study provides further evidence to support the role of MMP-9 in the pathogenesis of AAA, and indicates that the MMP9 C-1562T functional polymorphism may represent a genetic component contributing to susceptibility to this vascular disease.