Inheritance is thought to be rather complex. There is a good amount of evidence that shows the disease is autosomal dominant, with some penetrance. There is also the possibility of age related dependence. It is known that Marfan’s Syndrome and Ehler-Danlos Syndrome lead to an increased risk for development of FAD. Marfan’s Syndrome is not required to have an aortic<unk> . One study suggests that the chromosomal locus for the gene is 5q13-14. The same study found that other genes may be linked, and include loci for Marfan and Ehler-Danlos Syndromes, genes for metalloproteinase 3 and 9, and tissue inhibitor of malloproteinase 2 as well as two loci on chromosomes 5q13-14 and lq23.2-24. Still other studies show that mutations in smooth muscle cell-specific isoforms of alpha actin and beta myosin heavy chain may cause FAD. Mutations in the genes TGFBR 1 and 2 are known to cause<unk> s in aortas with normal diameter size (>4.3 cm) and gene FPN1 mutations typically affect aortas with larger diameters (<4.4 cm). There are several hypotheses which attempt to explain how the<unk>  physically occurs. The first states that a tear develops in the intima layer of the aorta which allows blood to flow from the lumen of the aorta into the intima. This event creates a<unk>  and essentially two lumens. The second hypothesis suggests that the vasa vasorum ruptures and causes a hemorrhage in the wall of the aorta. The hemorrhaging promotes tearing of the intima and eventually aortic<unk> . The major risk factors for FAD include high blood pressure, old age, haematoma, genetic weakening of aortic wall, cocaine use, pregnancy and diseases causing abnormal connective tissue. One study found that the average age(s) for the occurrence of<unk>  caused by degenerative aneurysm is 65 years and up.<unk> s thought to be the result of genetic mutations appear to be more likely to occur between the ages of 40 and 60. Another study found that 20% of patients with FAD have a close relative with a history of thoracic aortic aneurysm or<unk>  which suggests yet another major risk factor.
Familial aortic dissection
Familial thoracic aortic aneurysm
Familial atrial fibrillation
Takayasu's arteritis
Arterial tortuosity syndrome
Inflammatory aortic aneurysm
Monckeberg's arteriosclerosis
Coronary artery aneurysm