**3.1 Connective tissue disorders**

Connective tissue disorder is among the most common non-infective etiology of aortic root pathology. Marfan's syndrome, Ehlers-Danlos syndrome and Loeys-Dietz syndrome predominantly involve the elastic aortic root [11–13]. Marfan's syndrome is an autosomal dominant disorder characterized by mutation in the gene encoding for fibrillin-1. It leads to cystic medial necrosis and involves all connective tissue containing high percentages of elastin. Disease is multi-systemic; however aortic dissection remains an important cause of mortality [14]. The probability of aortic emergencies increases significantly when transverse aortic diameters is more than 45 mm [15].

Patients with vascular type of the Ehlers-Danlos syndrome are prone to aortic dissection rather than aneurysm, while patients with Loeys-Dietz syndrome are liable to have aortic aneurysm and dissection at younger age [11, 16, 17].
