In the euploid population there is a significant reduction in TIMP1 and TIMP3 expression in BAV-associated TAA and a highly significant increase in MMP2 and MMP9, which are both regulated by TIMP1 and TIMP3.[16] This results in a considerable MMP/TIMP imbalance in aneurysms compared to control aortas. This evidence concerns the gene MMP9 and aneurysm.