Our previous studies have identified COMP as a protective vascular ECM protein that maintains vascular homeostasis and counteracts the development of restenosis, atherosclerosis, and aneurysms.24, 25, 26 Given the dramatic reduction in plasma COMP levels observed in TAD patients after symptom onset, we investigated whether COMP expression was altered in the aortic wall during TAD progression. Here, COMP is linked to aneurysm.