COL3A1 and Ehlers-Danlos syndrome, vascular type: The prototypical monogenic form is vascular Ehlers-Danlos syndrome (vEDS), where COL3A1 mutations cause type III collagen deficiency, resulting in fragile arterial walls and a 15–20% lifetime CeAD risk, typically accompanied by red flags such as familial arterial rupture, characteristic facies (thin nose/lips), and translucent skin.