A bit heavy but let's use this as a starter..
Genetic Basis of Thoracic Aortic Aneurysms and Dissections ("TAAD")
"In particular a gene called ACTA2 appears to be responsible for vascular (blood vessel) disease. The technical name for the mutation is G48V (DNA change G 190T in exon 3). In general, we have two copies of each gene, one from the father and one from the mother. If there is a mutation in a gene, then it may not work properly. In the case of the gene called ACTA2, mutations may lead to problems in the smooth muscle cells in the walls of blood vessels. When the gene is altered, these muscle cells may not contract as well as they should.
The blood vessel disease associated with mutations in the ACTA2 gene is passed on in a manner known as autosomal dominant. Autosomal means that males and females are equally likely to inherit a mutation, and equally likely to pass it on. Dominant means that a change in one copy of the gene is sufficient to lead to disease."
Please feel free to REALLY get some input into this.
(..And many thanks to Dan for his valuable input for this subject..)