X-Linked Severe Syndromic Thoracic Aortic Aneurysm and Dissection, also known as x-linked severe syndromic taad, is related to meester-loeys syndrome and aortic aneurysm, familial thoracic 1. An important gene associated with X-Linked Severe Syndromic Thoracic Aortic Aneurysm and Dissection is BGN (Biglycan). Affiliated tissues include bone.