PCSK9 and triple-A syndrome: Meanwhile, a recent study proposed a protective role for MMP-12 in AAA formation and rupture, indicating that MMP-12 deletion in three differing mouse models (Ang II-infused Apoe−/− mice, Ang II-infused C57Bl/6J mice with over-expression of a gain-of-function PCSK9 variant, and Apoe−/− mice administered β-aminopropionitrile alongside perivascular porcine elastase application) accelerated death rates, which were attributed to accelerated aortic rupture [29].