SMAD3 and spontaneous coronary artery dissection: While FMD is the most common trait associated with SCAD, 5.1–8.2% of sporadic SCAD cases have been found to carry deleterious variants within genes associated with heritable CTDs and aortopathy, including vascular Ehlers–Danlos syndrome (COL3A1), Marfan syndrome (FBN1), and Loeys–Dietz syndrome (SMAD3) [7,39,40].