NOTCH1 and Marfan syndrome: Four Notch receptors (Notch 1‐4) have been described in humans and represent large transmembrane proteins that bind ligands expressed on adjacent cells.21 Because Notch plays a key role in neural crest migration and SMC differentiation during ascending aorta/aortic arch development, abnormal signalling may predispose to aneurysm formation.22 Although Notch signalling has not been studied in MFS, Notch1 gene mutations have been reported in patients with bicuspid aortic valves (BAV) and BAV aortopathy.