MFAP4 and aortic aneurysm: The presence of a BAV is a predisposing factor for the development of thoracic aortic aneurysms.31 To explore whether MFAP4 may be upregulated in early stages of this disease, we obtained aortic specimens from patients with BAV not presenting with aortic aneurysms (Table II in the online-only Data Supplement).