SMAD3 and spontaneous coronary artery dissection: SMAD2 was one of six genes associated with Loeys-Dietz syndrome (TGFBR1, TGFBR2, SMAD2, SMAD3, TGFB2, TGFB3) tested, and for which there was enrichment for rare variants in patients with SCAD when considered as a set of genes together; the other five genes did not meet statistical significance individually.